Tesis: "Extrasolare Planeten"

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Dominis, Dijana. "The role of binary stars in searches for extrasolar planets by microlensing and astrometry". Phd thesis, Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2006/1081/.

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Ser, Badia Daniel del. "TFAW: Noise filtering Through the use of the Wavelet Transform in Astronomy Photometric Data". Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/665320.

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The first confirmed detection of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found by radial velocity measurements in a four-day orbit around the nearby star 51 Pegasi by Mayor and Queloz in 1995. This finding encouraged the development of the method known as transit method that detects distant planets by measuring the small darkening of a star light curve as an orbiting planet passes between it and the Earth. The first detection of a transiting exoplanet, HD 209458 b, in 1999 by D. Charbonneau and collaborators and G. W. Henry and collaborators, and the discoveries obtained for this planet during follow- up observations (first planet with a detectable atmosphere containing oxygen and carbon, first detection of an evaporating hydrogen atmosphere and being one of the first two exoplanets to be directly observed spectroscopically) demonstrated the high scientific potential of planets discovered with this method. Transit photometry is currently the most effective and sensitive method for detecting extrasolar planets. Several surveys have taken this approach, such as the ground-based MEarth, SuperWASP, KELT, HAT-South, TFRM-PSES, NGTS or the Evryscope, as well as the space-based CoRoT, Kepler, the recently commissioned, TESS and the future PLATO missions. The photometric precision and accuracy achieved by an astronomical survey is a key factor in detecting a transiting signal or any other kind of variability. Many of the systematic variations in a given light curve are shared by light curves of other stars in the same data set. In order to remove those systematics, one can identify the objects in the field that suffer from the same kind of variations as the target (correlated noise) and then build and apply a filter based on the light curves of these comparison stars. Wavelets have unique properties that make them an ideal tool for analyzing signals of non- stationary nature. In comparison to the sine wave used in the Fourier transform, which is smooth and of infinite length, the wavelet is irregular in shape and compactly supported. Their irregular shape allows to analyze signals with discontinuities, transients, singularities and sharp changes, while their compactly supported nature allows temporal localization of the signal's features. Along this work we lay out the framework from which the main goal of this thesis, the Wavelet-based Trend Filtering Algorithm (TFAW) will be built from. TFAW is a wavelet-based modification of the Trend Filtering Algorithm developed by Kovács, Bakos and Noyes (2005). TFAW is a totally generic, Python-based, parallelized algorithm useful to improve the performance of signal detection, reconstruction and characterization, provided that a set of comparison light curves sharing the same systematics and trends as the target time series is available. differs from other wavelet-based noise-filtering algorithms in that it does not require any parametric model fitting or any extra computational method. TFAW estimates the noise contribution of the signal from its Stationary Wavelet Transform (SWT) at each iteration step and the de-noising is done through the subtraction of this contribution from the signal. TFAW de-noises the signal without modifying any of its intrinsic properties contrary to wavelet coefficient thresholding that can lead to distortions of the signal and introduce artificial oscillations or ripples around discontinuities. Tests conducted on simulated and real (coming from the TFRM-PSES, Evryscope, CoRoT and Kepler surveys) TFAW-filtered light curves show an improvement of 40% (although it can be higher) in their standard deviations with respect to the ones detrended with TFA, leading to a better characterization of the signal, without modifying its features. It improves the transit detection rate a factor 2-5 for low SNR signals with respect TFA. We demonstrate that the TFAW-filtered light curve yields better MCMC posterior distributions, diminishes the bias in the fitted transit parameters and their uncertainties and narrows the credibility intervals up to a factor 10 for simulated transits. Finally, TFAW is able to isolate the different underlying signals within a light curve with multiple periodic signals, such as multi-transit signals, transients, modulations or other kinds of stellar variabilities.
El descubrimiento del exoplaneta gigante 51 Pegasi b (detectado por Mayor y Queloz en 1995), mediante el método de las velocidades radiales, promovió el desarrollo de una nueva técnica de detección. Esta técnica, conocida como el método del tránsito, detecta exoplanetas midiendo el pequeño oscurecimiento del flujo estelar cuando el planeta pasa entre la estrella y el observador. El método del tránsito es, actualmente, el modo más eficiente y sensible para detectar planetas extrasolares. Muchas misiones han seguido este modo de observación, aquellas basadas en tierra, como MEarth, SuperWASP, KELT, HAT-South, TFRM-PSES, NGTS o el Evryscope; así como aquellas misiones espaciales como COnvection ROtation and planetary Transits (CoRoT), Kepler, TESS y la futura misión PLATO. La precisión fotométrica y la exactitud conseguida por una misión es un factor clave en la detección y caracterización de una señal correspondiente a un tránsito o a cualquier otro tipo de variabilidad. Las wavelets tienen unas propiedades que las hacen ideales para analizar señales de naturaleza no estacionaria. La forma irregular de las wavelets permite analizar señales con discontinuidades, singularidades o cambios bruscos mientras que su naturaleza compacta permite la localización temporal de las características de la señal. En este trabajo presentamos el Wavelet-based Trend Filtering Algorithm (TFAW). TFAW es un algoritmo totalmente genérico, desarrollado y paralelizado en Python basado en el Trend Filtering Algorithm (TFA) desarrollado por Kovács, Bakos y Noyes (2005). El algoritmo es útil para mejorar el rendimiento en la detección, reconstrucción y caracterización de señales astrofísicas. TFAW difiere de otros métodos de filtrado de ruido basados en wavelets en que no requiere ningún modelo de ajuste paramétrico o cualquier otro método computacional. TFAW estima la contribución de ruido de la señal a partir de su Stationary Wavelet Transform (SWT) y el filtrado se realiza eliminando esta contribución de la señal. Además, TFAW es capaz de hacer el filtrado de la señal sin modificar ninguna de sus características intrínsecas a diferencia de otros métodos como los umbrales calibrados de los coeficientes wavelet que pueden dar lugar a distorsiones de la señal o introducir oscilaciones o perturbaciones artificiales alrededor de discontinuidades. En curvas de luz simuladas, TFAW mejora la detección de tránsitos en un factor 2.5 para señales con bajo SNR. TFAW proporciona una mejor representación y caracterización de señales simuladas y reales (provenientes de las misiones TFRM-PSES, Evryscope, CoRoT y Kepler) afectadas por ruido. Así mismo, proporciona mejores probabilidades a posteriori y una disminución del bias y las incertidumbres de los parámetros ajustados mediante MCMC.

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Nascimento, Sanzia Alves do. "Propriedades f?sicas de planetas extrasolares". Universidade Federal do Rio Grande do Norte, 2008. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18579.

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Made available in DSpace on 2015-03-03T15:15:22Z (GMT). No. of bitstreams: 1 SanziaAN.pdf: 964619 bytes, checksum: 25b161330259b5777dcaa8cf03c1242b (MD5) Previous issue date: 2008-04-22
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
ROTATION is one the most important aspects to be observed in stellar astrophysics. Here we investigate that particularly in stars with planets. This physical parameter supplies information about the distribution of angular momentum in the planetary system, as well as its role on the control of dierent phenomena, including coronal and cromospherical emission and on the ones due of tidal effects. In spite of the continuous solid advances made on the study of the characteristics and properties of planet host stars, the main features of their rotational behavior is are not well established yet. In this context, the present work brings an unprecedented study about the rotation and angular momentum of planet-harbouring stars, as well as the correlation between rotation and stellar and planetary physical properties. Our analysis is based on a sample of 232 extrasolar planets, orbiting 196 stars of dierent luminosity classes and spectral types. In addition to the study of their rotational behavior, the behavior of the physical properties of stars and their orbiting planets was also analyzed, including stellar mass and metallicity, as well as the planetary orbital parameters. As main results we can underline that the rotation of stars with planets present two clear features: stars with Tef lower than about 6000 K have slower rotations, while among stars with Tef > 6000 K we and moderate and fast rotations, though there are a few exceptions. We also show that stars with planets follow mostly the Krafts law, namely < J > / v rot. In this same idea we show that the rotation versus age relation of stars with planets follows, at least qualitatively, the Skumanich and Pace & Pasquini laws. The relation rotation versus orbital period also points for a very interesting result, with planet-harbouring stars with shorter orbital periods present rather enhanced rotation
ROTA??O ? um dos importantes aspectos a ser observado na astrof?sica estelar. Por isto, neste trabalho, investigamos este par?metro no estudo das estrelas hospedeiras de planetas. Par?metro f?sico este que fornece informa??o sobre a distribui??o do momentum angular dos sistemas planet?rios, bem como sobre o seu papel nos mais diferentes fen?menos, incluindo emiss?o cromosf?rica e coronal e sobre aqueles decorrentes de efeitos de mar?. Apesar dos cont?nuos avan?os feitos no estudo das caracter?sticas e das propriedades destes objetos, as principais caracter?sticas de seu comportamento rotat?rio ainda n?o est?o bem estabelecidas. Neste contexto, o presente trabalho traz um estudo pioneiro sobre a rota??o e o momentum angular das estrelas hospedeiras de planetas, bem como sobre a correla??o entre rota??o e par?metros f?sicos estelares e planet?rios. Nossa an?lise ? baseada em uma amostra de 232 planetas extrasolares, orbitando 196 estrelas de diferentes classes de luminosidade e tipos espectrais. Al?m do estudo do comportamento rotacional dessas estrelas, re-visitamos o comportamento das propriedades f?sicas destas estrelas e de seus planetas, incluindo a massa estelar e a metalicidade, bem como os par?metros orbitais planet?rios. Como resultados principais, podemos sublinhar que a rota??o das estrelas com planetas apresenta duas claras caracter?sticas: estrelas com Tef inferiores aproximadamente 6000 K possuem rota??es mais baixas, enquanto que entre aquelas com Tef > 6000 K encontramos rota??es modv eradas e altas, embora algumas exce??es. N?s mostramos tamb?m que as estrelas com planetas seguem, em sua maioria, a lei do Kraft, a saber < J > / v rot. Nesta mesma linha n?s mostramos que a rela??o rota??o versus idade das estrelas com planetas segue, ao menos qualitativamente, como qualquer outra estrela de campo ou de aglomerado, a lei de Skumanich e de Pace & Pasquini. Um resultado interessante a ser destacado ? a rela??o rota??o versus per?odo orbital, que aponta para uma tend?ncia de que as estrelas que abrigam planetas com per?odo orbital menores apresentam rota??es mais real?adas

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4

Hood, Ben Andrew Ashcom. "Extrasolar planet search and characterisation". Thesis, St Andrews, 2007. http://hdl.handle.net/10023/359.

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5

Howe, Alex Ryan. "Topics in Extrasolar Planet Characterization". Thesis, Princeton University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10167564.

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I present four papers exploring different topics in the area of characterizing the atmospheric and bulk properties of extrasolar planets. In these papers, I present two new codes, in various forms, for modeling these objects. A code to generate theoretical models of transit spectra of exoplanets is featured in the first paper and is refined and expanded into the APOLLO code for spectral modeling and parameter retrieval in the fourth paper. Another code to model the internal structure and evolution of planets is featured in the second and third papers. The first paper presents transit spectra models of GJ 1214b and other super-Earth and mini-Neptune type planets—planets with a “solid”, terrestrial composition and relatively small planets with a thick hydrogen-helium atmosphere, respectively—and fit them to observational data to estimate the atmospheric compositions and cloud properties of these planets. The second paper presents structural models of super-Earth and mini-Neptune type planets and estimates their bulk compositions from mass and radius estimates. The third paper refines these models with evolutionary calculations of thermal contraction and ultraviolet-driven mass loss. Here, we estimate the boundaries of the parameter space in which planets lose their initial hydrogen-helium atmospheres completely, and we also present formation and evolution scenarios for the planets in the Kepler-11 system. The fourth paper uses more refined transit spectra models, this time for hot jupiter type planets, to explore the methods to design optimal observing programs for the James Webb Space Telescope to quantitatively measure the atmospheric compositions and other properties of these planets.

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6

Carter, Andrew James. "Observation and modeling of extrasolar planets". Thesis, Open University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578669.

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The field of exoplanet research has currently yielded the discovery of 552 planets. This figure includes 132 transiting planets which can be studied in greater detail and have formed the cornerstone of research to characterise the exoplanet population. In particular, such studies seek to analyse the planetary atmospheres, but research has thus far yielded more questions than answers. Exoplanetary atmospheric studies have typically focussed on one planet apiece - complicating any comparative analysis as every result employs different methods and instruments. For a comprehensive, comparative study, a robust and reliable means of reducing and analysing such observations is required, along with a body of data from a single instrument. One such instrument is the Bubble Space Telescope (BST) whose NICMOS (Near Infrared Camera and Multi-Object Spectrometer) instrument has observed the transits of nine extrasolar planets across multiple wavelengths in the near-infrared. A robust pipeline has been developed to reduce all such observations using the fame techniques. This pipeline reduces grism images of an exoplanet host star across a transit event. These exposures are checked for bad pixels, flat fielded and background-subtracted before robust extraction of a transit light curve. This light curve is then detrended to remove systematic noise by application of a new technique developed in this study. Following detrending, the light curve is modelled using a be- spoke MCMC (Markov-Chain Monte-Carlo) algorithm to determine the planetary parameters. A continuum of wavelength-dependent transit light curves is also extracted, detrended and modelled to de- termine the variation in transit depth with wavelength; and .hereby infer the transmission spectrum of the planet's atmosphere. The finished pipeline has been applied to three sets of HST NIC- MOS observations covering the transits of WASP-2b, HD189733b and GJ436b. For each data set, a new set of planetary parameters has been derived and for WASP-2b and HD189733b an atmospheric transmission spectrum extracted. Both spectra show signs of atmospheric haze and molecular absorption, but also evidence of residual systematic noise, complicating analysis.

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7

Muterspaugh, Matthew Ward. "Binary star systems and extrasolar planets". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34646.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.
Includes bibliographical references (p. 121-137).
For ten years, planets around stars similar to the Sun have been discovered, confirmed, and their properties studied. Planets have been found in a variety of environments previously thought impossible. The results have revolutionized the way in which scientists understand planet and star formation and evolution, and provide context for the roles of the Earth and our own solar system. Over half of star systems contain more than one stellar component. Despite this, binary stars have often been avoided by programs searching for planets. Discovery of giant planets in compact binary systems would indirectly probe the timescales of planet formation, an important quantity in determining by which processes planets form. A new observing method has been developed to perform very high precision differntial astrometry on bright binary stars with separations in the range of 0.1 - 1.0 arcseconds. Typical measurement precisions over an hour of integration are on the order of 10 micro-arcseconds (as), enabling one to look for perturbations to the Keplerian orbit that would indicate the presence of additional components to the system. This method is used as the basis for a new program to find extrasolar planets. The Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) is a search for giant planets orbiting either star in 50 binary systems. The goal of this search is to detect or rule out planets in the systems observed and thus place limits on any enhancements of planet formation in binaries. It is also used to measure fundamental properties of the stars comprising the binary, such as masses and distances, useful for constraining stellar models at the 10-3 level.
(cont.) This method of differential astrometry is applied to three star systems. Equulei is among the most well-studied nearby binary star systems. Results of its observation have been applied to a wide range of fundamental studies of binary systems and stellar astrophysics. PHASES data are combined with previously published radial velocity data and other previously published differential astrometry measurements to produce a combined model for the system orbit. The distance to the system is determined to within a twentieth of a parsec and the component masses are determined at the level of a percent. n Pegasi is a well-known, nearby triple star system consisting of a "wide" pair with semi-major axis 235 milli-arcseconds, one component of which is a single-line spectroscopic binary (semi-major axis 2.5 milli-arcseconds). Using high-precision differential astrometry and radial velocity observations, the masses for all three components are determined and the relative inclination between the wide and narrow pairs' orbits is found to be 43.8 ± 3.0 degrees, just over the threshold for the three body Kozai resonance. The system distance is determined to a fifth of a parsec, and is consistent with trigonometric parallax measurements. V819 Herculis is a well-studied triple star system consisting of a "wide" pair with 5.5 year period, one component of which is a 2.2-day period eclipsing single-line spectroscopic binary. Differential astrometry measurements from PHASES determine the relative inclination of the short- and long-period orbits. Finally, the prospects for finding planets that simultaneously circle both stars in a binary system are evaluated. Planet searches of this type would represent a complementary investigation to PHASES and contribute similar scientific results.
by Matthew Ward Muterspaugh.
Ph.D.

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8

Borgniet, Simon. "Recherche et caractérisation de planètes géantes autour d'étoiles massives et/ou jeunes de la Séquence Principale : modélisation de l'activité d'étoiles de type solaire et impact sur la détection de planètes de masse terrestre". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY063/document.

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La recherche des exoplanètes traverse aujourd'hui une période décisive. D'un côté, notre connaissance des planètes géantes gazeuses s'est considérablement développée, et l'objectif de la recherche est maintenant de caractériser leurs propriétés physiques et de mieux comprendre leurs mécanismes de formation et d'évolution. D'un autre côté, la précision et la stabilité des instruments ont atteint un niveau qui rend techniquement possible la détection de planètes telluriques situées dans la zone habitable de leur étoile. Cependant, les perturbations du signal dues à l'étoile elle-même constituent un obstacle important à cette avancée. Mon travail de thèse se situe à la rencontre de ces problématiques. Il a consisté d'une part en l'analyse de deux relevés de vitesses radiales visant des étoiles relativement exotiques pour la recherche d'exoplanètes: les étoiles naines de type AF massives. Ce travail a donné lieu à la première caractérisation de la population de planètes géantes autour de ces étoiles et a montré que les mécanismes de migration planétaire étaient au moins partiellement inhibés autour de ces étoiles par rapport aux étoiles de type FGKM. Dans un second temps, j'ai conduit les observations et l'analyse des premiers résultats de deux grands relevés de vitesses radiales débutés pendant ma thèse et visant à détecter des planètes géantes en orbite autour d'étoiles jeunes et proches. Ces étoiles jeunes sont les seules sources pour lesquelles une exploration complète des planètes géantes à toutes les séparations devient possible, par combinaison des techniques de vitesses radiales et de l'imagerie. Cette combinaison permettra de tester de manière unique les modèles de formation et d'évolution planétaire. Les résultats provisoires de ces relevés indiquent une absence de planètes géantes à très courte séparation (Jupiters chauds) autour de nos cibles. Un autre résultat intéressant est la découverte d'une binaire spectroscopique eccentrique au centre d'un système planétaire imagé à grande séparation. Pour compléter cette approche observationnelle et mieux évaluer la détectabilité des exoplanètes semblables à la Terre, j'ai étalonné et caractérisé un modèle entièrement paramétré de l'activité d'une étoile semblable au Soleil et de son impact sur les vitesses radiales. Je l'ai dans un premier temps étalonné en comparant ses résultats à ceux obtenus à partir d'observations des zones actives du Soleil, puis je l'ai utilisé pour caractériser l'impact de l'inclinaison de l'étoile sur le signal induit par l'activité. Ce modèle paramétré ouvre de très nombreuses possibilités, étant en effet potentiellement adaptable à des types d'étoiles et d'activité différents. Il permettrait ainsi de caractériser les perturbations en vitesses radiales attendues pour chaque cas testé, et donc à la fois de déterminer quelles étoiles et quels types d'activité sont les plus favorables pour la détection de planètes de masse terrestre dans la zone habitable. En explorant ces trois problématiques en apparence très diverses mais complémentaires, j'y ai retrouvé un motif commun, celui de l'importance des étoiles elles-mêmes et de la physique stellaire pour la recherche d'exoplanètes
The search for exoplanets has reached a decisive moment. On the one hand, our knowledge of giant gaseous planets has significantly developed, and the aim of the research is now to characterize their physical properties and to better understand the formation and evolution processes. On the other hand, the instrumental precision and stability have reached a level that makes it technically possible to detect telluric planets in the habitable zone of their host star. However, the signal alterations induced by the star itself definitely challenge this breakthrough. My PhD stands at the crossroads of these problems. It consisted first in the analysis of two radial velocity surveys dedicated to stars somewhat exotic to exoplanet searches: the massive AF dwarf stars. This work has led to the first characterization of the giant planet population found around these stars and has showed that the planetary migration mechanisms were at least partially inhibited around these stars compared to FGKM stars. I then made the observations and the first analysis of two radial velocity surveys dedicated to the search for giant planets around young, nearby stars. Young stars are the only sources for which a full exploration of the giant planets at all separations can be reached, through the combination of radial velocities techniques and direct imaging. Such a combination will allow to test uniquely the planetary formation and evolution processes. The first results of these surveys show an absence of giant planets at very short separations (Hot Jupiters) around our targets. Another interesting result is the detection of an eccentric spectroscopic binary at the center of a planetary system imaged at a wide separation. To complete this observational approach and better estimate the detectability of Earth-like planets, I calibrated and characterized a fully parameterized model of the activity pattern of a Sun-like star and its impact on the radial velocities. I first calibrated it by comparing it to the results obtained with observations of the solar active structures, and then characterized the impact of stellar inclination on the activity-induced signal. Such a fully parameterized model is potentially adaptable to different types of stars and of activity and would thus allow to characterize the expected radial velocity jitter for each tested case, and then allow both to determine which types of stars and of activity patterns are the most favorable for detecting Earth-like planets in the habitable zone. While investigating these three seemingly different but complementary topics, I found that they shared a basic feature, namely the importance of the stars themselves and of stellar physics in exoplanet searches

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9

Leigh, Christopher. "The detection and characterisation of extrasolar planets". Thesis, University of St Andrews, 2004. http://hdl.handle.net/10023/12943.

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Since the discovery of 51 Pegasi b in 1995, continued observations have indirectly identified over 110 planetary objects. These Jupiter-mass objects cause their host star to "wobble" slightly about the common centre-of-mass of the system, which is detectable as radial motion in high-precision Doppler spectroscopy. Of the known planets, approximately 20% are found to orbit within 0.1 AU of the star, whilst the transit of HD209458 has inferred the gas-giant nature of these close-in extrasolar giant planets (CEGPs). The discovery of CEGPs has produced a wave of speculative theory as to the exact nature of these objects, and how they came to exist so close to their parent star. Our spectroscopic technique provides a method of achieving the direct detection of a CEGP atmosphere, the results of which will allow us to test emerging models that aim to predict the atmospheric nature of CEGPs and may provide additional information on the orbital inclination and mass of the planet. We start with a historical review of the field of extrasolar planets, followed by an introduction to the fundamental concepts which underpin the reflection of starlight from a planet's surface. We then investigate the prospects of detecting such a reflection, before detailing the technique we have devised and applied here to two known CEGP hosts. In the first instance, r Bootis, we combined observations at the 4.2-m William Herschel telescope in 1998, 1999 and 2000. The dataset comprised 893 high-resolution échelle spectra with a total integration time of 75hr 32min spanning 17 nights. We establish an upper limit on the planet's geometric albedo p < 0.39 (at the 99.9% significance level) at the most probable orbital inclination i ~ 36 deg, assuming a grey albedo, a Venus-like phase function and a planetary radius Rp - 1.2RJup. Although a weak candidate signal appears near to the most probable radial velocity amplitude, its statistical significance is insufficient for us to claim a detection with any confidence. In the second instance, HD75289, 4 nights of VLT(UT2)/UVES observations were secured in 2003 Jan, yielding 684 high-resolution spectra with a total integration time of 26 hours. We establish an upper limit on the planet's geometric albedo p < 0.12 (to the 99.9% significance level) at the most probable orbital inclination i ~/= 60 deg, assuming a grey albedo, a Venus-like phase function and a planetary radius Rp = 1.6RJup. In both cases, we are able to rule out some combinations of the predicted planetary radius and atmospheric albedo models with high, reflective cloud decks.

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Herrero, Casas Enrique. "Stellar activity in exoplanet hosts". Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284220.

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Most of the efforts on the search and characterization of Earth-like exoplanets are currently focused on low mass stars. Some important properties related to the structure and processes in this type of stars are still unknown, so a careful characterization is essential as one of the next steps in exoplanet sciences. The characterization of stellar activity in low mass stars was carried out through several techniques that allowed us both to model and to simulate the relationships between the observational data and the stellar properties. Several empyrical relations for low mass stars allow to find correlations between certain activity indicators and the rotation period. These have permitted us to generate synthetic samples of stars with stochastic distributions of stellar and geometric properties allowing to estimate the inclination of the rotation axis from the distribution in the activity-vsini diagram. The methodology was applied to a sample of 1200 observed low mass stars and the best candidates for a targeted transit search were selected. Spot modelling techniques allow to obtain physical information about the stellar surface from time series photometric and spectroscopic data. In this work we analyse Kepler photometry of LHS 6343 A, an M-dwarf being eclipsed by a brown dwarf companion every 12.718 days, and showing photometric oscillations with the same periodicity and a phase lag of 100º from the eclipses. The accurate modeling of the Kepler data allowed to explain these oscillations with the presence of active regions appearing at a fixed longitude, thus suggesting a possible magnetic connection between both components. On the other hand, we also studied an alternative explanation for the photometric oscillations in LHS 6343 A in terms of the Doppler beaming effect, showing that this could be the main cause of the observed oscillations. Stellar activity effects are responsible for the noise observed at different amplitude and timescales on time series data. Such noise represents one of the main limitations for exoplanetary sciences. In order to characterize it, we designed a methodology to simulate the photosphere of an active rotating star through the integration of small surface elements from Phoenix atmosphere models. This allows to characterize the signal produced by activity and further study its relationship with the stellar properties, as well as the possible effects produced on exoplanet measurements. The methodology allowed us to present several strategies in order to correct or reduce the effects of spots on the photometry of exoplanet transits, as these may induce significant variations on the measurement of the planetary radius. We focused on a comprehensive analysis of HD 189733, a K5 star hosting a giant planet, which has simultaneous photometric (MOST) and spectroscopic (SOPHIE) data available. An accurate surface map was obtained using the methodology above, accurately reproducing the light curve and radial velocity observations. Such map was used in order to study the effects of activity on the exoplanet transits. We showed that the effects of spot-crossing events are significant even for mid-infrared wavelengths. Moreover, the chromatic effects of spots not occulted by the planet show a signal with a wavelength dependence and amplitude that are very similar to the signature of the atmosphere of a planet dom- inated by dust. The radial velocity theoretical curve is in agreement with the observations up to the typical instrumental systematics of SOPHIE. The results from this work conclude that it is essential to correctly model the stellar activity signals for exoplanetary sciences, and we provide some tools and strategies to characterize and reduce such effects and extract astrophysical information.
Actualment, la major part dels esforços per la cerca i caracterització d’exoplanetes de tipus terrestre es centren en aquells que orbiten estrelles de baixa massa. Algunes de les característiques importants de l’estructura i els processos d’aquest tipus d’estrelles són encara poc coneguts, i per tant és important fer-ne un estudi acurat com un dels següents passos en el camp de l’exoplanetologia. En concret, el senyal produïit pels fenòmens d’activitat estel•lar, degut a la presència de taques i fàcules, introdueix variacions en les mesures fotomètriques i espectroscòpiques amb una periodicitat modulada per la rotació de l’estrella. En aquesta tesi s’ha realitzat un estudi dels fenòmens d’activitat a la fotosfera d’estrelles de baixa massa a través de diverses tècniques que ens han permès modelitzar o bé simular les relacions entre les propietats estel•lars i les dades observables. La simulació de mostres estadístiques d’estrelles basada en les relacions conegudes entre l’activitat estel•lar i la rotació ha permés implementar una tècnica per estimar la inclinació de l’eix de les estrelles a partir de mesures espectroscòpiques, resultant en un catàleg amb les millors candidates per una cerca de planetes amb trànsits. Per a la caracterització dels fenòmens relacionats amb l’activitat i un estudi acurat dels seus efectes sobre les mesures i cerques d’exoplanetes, s’ha aprofitat la disponibilitat de dades fotomètriques de Kepler juntament amb tècniques de modelització de taques, centrant-nos particularment en l’estudi de LHS 6343 A per obtenir informació d’activitat en la seva superfície. A més, s’ha dissenyat un simulador dels efectes d’activitat a la fotosfera basat en tècniques d’integració de superfície i models d’atmosfera Phoenix, que permet obtenir sèries temporals de dades sintètiques i estudiar els efectes de les regions actives sobre les mesures de trànsits de planetes. En particular, s’ha modelat el cas de HD189733. Els resultats d’aquest treball conclouen que és essencial una correcta modelització del senyal de l’activitat estel•lar en el camp de l’exoplanetologia, i es proporcionen algunes eines i estratègies per tal de caracteritzar i corregir aquests efectes i obtenir-ne informació astrofísica.

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11

Doellinger, Michaela. "Hunting for extrasolar planets around K giants". Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-99700.

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12

Lewis, Nikole Kae. "Atmospheric Circulation of Eccentric Extrasolar Giant Planets". Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/242352.

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This dissertation explores the three-dimensional coupling between radiative and dynamical processes in the atmospheres of eccentric extrasolar giant planets GJ436b, HAT-P-2b, and HD80606b. Extrasolar planets on eccentric orbits are subject to time-variable heating and probable non-synchronous rotation, which results in significant variations in global circulation and thermal patterns as a function of orbital phase. Atmospheric simulations for the low eccentricity (e=0.15) Neptune sized planet GJ436b reveal that when Neptune-like atmospheric compositions are assumed day/night temperature contrasts and equatorial jet speeds are significantly increased relative to models that assume a solar-like composition. Comparisons between our theoretical light curves and recent observations support a high metallicity atmosphere with disequilibrium carbon chemistry for GJ436b. The analysis of full-orbit light curve observations at 3.6 and 4.5 microns of the HAT-P-2 system reveal swings in the planet's temperature of more than 900 K during its significantly eccentric (e=0.5) orbit with a four to six hour offset between periapse passage and the peak of the planet's observed flux. Comparisons between our atmospheric model of HAT-P-2b and the observed light curves indicate an increased carbon to oxygen ratio in HAT-P-2b's atmosphere compared to solar values. Atmospheric simulations of the highly eccentric (e=0.9) HD80606b show that flash-heating events completely alter planetary thermal and jet structures and that assumptions about the rotation period of this planet could affect the shape of light curve observations near periapse. Our simulations of HD80606b also show the development an atmospheric shock on the nightside of the planet that is associated with an observable thermal signature in our theoretical light curves. The simulations and observations presented in this dissertation mark an important step in the exploration of atmospheric circulation on the more than 300 exoplanets known to possess significantly non-zero eccentricities.

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13

Kipping, D. M. "The transits of extrasolar planets with moons". Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1306758/.

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The search for extrasolar planets is strongly motivated by the goal of characterizing how frequent habitable worlds and life may be within the Galaxy. Whilst much effort has been spent on searching for Earth-like planets, large moons may also be common, temperate abodes for life as well. The methods to detect extrasolar moons, or “exomoons” are more subtle than their planetary counterparts and in this thesis I aim to provide a method to find such bodies in transiting systems, which offer the greatest potential for detection. Before one can search for the tiny perturbations to the planetary signal, an understanding of the planetary transit must be established. Therefore, in Chapters 3 to 5 I discuss the transit model and provide several new insights. Chapter 4 presents new analytic expressions for the times of transit minima and the transit duration, which will be critical in the later search for exomoons. Chapter 5 discusses two sources of distortion to the transit signal, namely blending (with a focus on the previously unconsidered self-blending scenario) and light curve smearing due to long integration times. I provide methods to compensate for both of these effects, thus permitting for the accurate modelling of the planetary transit light curve. In Chapter 6, I discuss methods to detect exomoons through their gravitational influence on the host planet, giving rise to transit timing and duration variations (TTV and TDV). The previously known TTV effect is updated with a new model and the associated critical problems are outlined. I then predict a new effect, TDV, which solves these problems, making exomoon detection viable. Chapter 7 presents a feasibility study for detecting habitable-zone exomoons with Kepler, where it is found that moons down to 0.2M⊕ are detectable. Finally, conclusions and future work are discussed in Chapter 8.

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14

Nikku, Madhusudhan 1980. "Retrieval of atmospheric properties of extrasolar planets". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/63006.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 133-137).
We present a new method to retrieve molecular abundances and temperature profiles from exoplanet atmosphere photometry and spectroscopy. Our method allows us to run millions of 1-D atmosphere models in order to cover the large range of allowed parameter space. In order to run such a large number of models, we have developed a parametric pressure-temperature (P-T) profile coupled with line-by-line radiative transfer, hydrostatic equilibrium, and energy balance, along with prescriptions for non-equilibrium molecular composition and energy redistribution. The major difference from traditional 1-D radiative transfer models is the parametric P-T profile, which essentially means adopting energy balance only at the top of the atmosphere and not in each layer. We see the parametric P-T model as a parallel approach to the traditional exoplanet atmosphere models that rely on several free parameters to encompass unknown absorbers and energy redistribution. The parametric P-T profile captures the basic physical features of temperature structures in planetary atmospheres (including temperature inversions), and reproduces a wide range of published P-T profiles, including those of solar system planets. We apply our temperature and abundance retrieval method to two exoplanets which have the best data available, HD 189733b and HD 209458b. For each planet, we compute - 107 atmospheric spectra on a grid in the parameter space, and report contours of the error surface, given the data. For the day-side of HD 189733b, we place constraints on the atmospheric properties based on three different data sets available. Our best-fit models to one of the data sets allow for very efficient daynight energy redistribution in HD 189733b. The different constraints on molecular abundances confirm the presence of H20, CH4 , CO and CO 2 in HD 189733b. Our results also rule out the presence of a thermal inversion in this planet. The model constraints due to the different data sets indicate that the planetary atmosphere is variable, both, in its energy redistribution state and in the chemical abundances. The variability is evident in the data; some key observations with different instruments at the same wavelength differ at the - 2- level. If, on the other hand, the differences in data represent underestimated errors, and if all the data sets have to be reconciled simultaneously, then we are unable to make specific constraints on the molecular abundances or on the temperature profile, beyond identification of molecules and the presence or absence of a thermal inversion. For HD 209458b, we confirm and constrain a thermal inversion in the day-side atmosphere, and the data allows for very efficient day-night redistribution of energy. We report detection of CO, CH4 and CO 2 on the dayside of HD 209458b, along with placing an upper-limit on the amount of H2 0. We also report atmospheric models for three transiting exoplanets with limited data: TrES-2, HAT-P-7b, GJ 436b. For TrES-2 and HAT-P-7b, where only four observations each are available, we find that the data can be fit with models with and without thermal inversions, if we make no assumptions of chemical equilibrium. Finally, in this work, we report the first steps towards developing a parameter estimation procedure for exoplanetary atmospheres. We demonstrate with simulated data that our model can be used with a formal Bayesian parameter estimation algorithm, like MCMC, to place constraints on the atmospheric properties of hot Jupiters.
by Nikku, Madhusudhan.
Ph.D.

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15

Gaudi, B. Scott. "Microlensing and the search for extrasolar planets /". The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488199501405399.

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16

Chagas, Maria Liduina das. "Atividade cromosf?rica induzida por planetas extrasolares gigantes". Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18586.

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Made available in DSpace on 2015-03-03T15:15:24Z (GMT). No. of bitstreams: 1 MariaLC_DISSERT.pdf: 1088429 bytes, checksum: d83b8fb43c1412d9b152e1fe935f4d60 (MD5) Previous issue date: 2010-08-02
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
In the present work, we have analyzed the behavior of the chromospheric activity of stars with planets, as a function of different planetary parameters, searching for possible effects of planets on the chromosphere of the hosting star. For this study we have selected a sample of 73 main sequence stars with planets, of spectral types F, G and K. Our analysis shows that among stars with planets presenting semi-major axis smaller than 0.15 AU, a few ones present enhanced CaII emission flux, paralleling recent results found in the literature for coronal X-ray flux. Nevertheless, in contrast to Kashyap et al. (2008), who claim that enhanced X-ray flux in stars with planets is associated to massive close-in planetary companions, we suggest that such an aspect, at least in the context of CaII emission flux, is rather an effect of stellar sample selection. We have also studied the behavior of the CaII emission as a function of orbital parameters such as orbital period and eccentricity, and no clear trend was found, reinforcing our present suggestion that enhanced chromospheric activity in stars with planets is an intrinsic stellar phenomenon
No presente trabalho, analisamos o comportamento da atividade cromosf?rica de estrelas com planetas em fun??o de diferentes par?metros planet?rios, procurando poss?veis efeitos do planeta sobre a cromosfera da estrela hospedeira. Para esse estudo selecionamos uma amostra de 73 estrelas da sequ?ncia principal com planetas de tipo espectral F, G e K. Nossa an?lise mostra que entre as estrelas com planetas que apresentam semieixo maior menor que 0,15 UA (1,5 1011 m), algumas apresentam elevada emiss?o do fluxo de CaII, em paralelo com recentes resultados encontrados para o fluxo de raio-X. No entanto, em contraste a Kashyap et al. (2008), que afirmam que o aumento no fluxo de raio-X em estrelas com planetas est? associado a grande proximidade do companheiro planet?rio. N?s sugerimos que tal aspecto, pelo menos no contexto de emiss?o de fluxo de CaII, seja devido a um efeito de sele??o da amostra. Estudamos tamb?m o comportamento da emiss?o de fluxo de CaII em fun??o de par?metros orbitais como per?odo orbital e excentricidade, e nenhuma tend?ncia clara foi encontrada, refor?ando a nossa sugest?o de que o aumento da atividade cromosf?rica de estrelas com planetas ? um fen?meno estelar intr?nseco

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17

Natalini, Simone. "Ricerca di pianeti extrasolari: microlensing planet finder". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21585/.

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Questa tesi studia il fenomeno astronomico chiamato lente gravitazionale, in cui un oggetto massivo (lente) causa una curvatura della luce proveniente da un oggetto sullo sfondo (sorgente). Il lavoro è una ricerca bibliografica che parte da manuali di relatività generale e ne approfondisce gli argomenti con articoli scientifici più specifici e alcuni testi di presentazione di progetti pubblicati dalla NASA. Nel dettaglio si tratta il caso particolare dei fenomeni di microlensing, in cui l’effetto della lente sia piccolo e non si riesca ad individuare più di un’immagine distinta. Lo studio di questo tipo di fenomeni è molto importante nel campo della ricerca di pianeti extrasolari poiché copre un range di osservazione che non sarebbe possibile con altri metodi. Lo sviluppo dell’argomento procede partendo dallo studio della lente gravitazionale come caso generale per estrarre successivamente l’equazione ottica. Vengono poi studiati i parametri associati a quest’ultima e l’analisi dei modelli necessari per spiegare il fenomeno in esame. A ciò segue l’analisi delle caratteristiche e dei vantaggi di una ricerca planetaria di questo tipo eseguita da un telescopio orbitale. In conclusione si mostrano le caratteristiche e lo scopo di una proposta di missione spaziale presentata alla NASA per eseguire un censimento di pianeti extrasolari che possa misurare tutte le possibili distanze di ciascuno di essi dal proprio sole. In essa si rileva la necessità di dedicare una missione spaziale alla osservazione di una sezione di cielo appartenente alla costellazione del Sagittario per eseguire un censimento planetario statisticamente accurato, altrimenti impossibile a causa della bassa sensibilità dell’osservazione del cielo con un telescopio posizionato a terra e della totale mancanza di altri metodi per osservare corpi orbitanti e non orbitanti con masse così piccole.

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18

Steffen, Jason. "Detecting new planets in transiting systems /". Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/9686.

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19

Goukenleuque, Cedric. "Atmosphere des planetes extrasolaires geantes : un modele d'equilibre radiatif". Paris 6, 1999. https://tel.archives-ouvertes.fr/tel-00009725.

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Les observations directes, notamment spectroscopiques, permettront de determiner la nature et la composition chimique de l'atmosphere des jupiter chauds, mais il est essentiel d'elaborer preliminairement un modele atmospherique theorique dans le but de contraindre les techniques d'observation. Dans cette optique, nous avons developpe un modele d'equilibre radiatif adapte aux planetes extrasolaires de type jovien, chauffees par leur etoile centrale. La modelisation fournit la determination de la structure thermique moyenne, mais aussi le spectre reflechi et le spectre d'emission thermique pour des planetes de distance orbitale 0. 05 a 1 unite astronomique. Dans ce modele, l'atmosphere est limitee au bas par un nuage optiquement epais. Dans tous les cas, un resultat majeur du modele est marque par l'absence d'inversion de temperature dans la structure thermique de l'atmosphere, contrairement aux planetes geantes du systeme solaire. A l'exception de la planete la plus distante (1 ua) de l'echantillon des planetes modelisees, nous trouvons que l'atmosphere est subadiabatique sur toute la grille de pression, ce qui valide l'hypothese d'equilibre radiatif. La distribution verticale des especes chimiques les plus abondants de l'atmosphere, dans des conditions solaires, est discutee selon la distance de la planete a l'etoile. Le spectre d'emission thermique est domine par les bandes de l'eau, vues en absorption, et revele une fenetre a 4 m, accompagnee d'un flux de plus en plus fort a 10 m pour les planetes les plus froides. Nous avons enfin etudie la detectabilite des signatures spectrales de l'atmosphere des jupiters chauds, au foyer de grands telescopes (vlt, keck,) en mode non-interferometrique. Les spectres synthetiques ont ete calcules pour 51 peg b (t e f f = 1200 k) en particulier, dans la bande 3 de ch 4 et (1-0) de co.

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20

Veras, Dimitri George. "The orbital evolution of extrasolar planets after formation". Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273687.

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21

Cooper, Curtis Steven. "Meteorologies of Brown Dwarfs and Extrasolar Giant Planets". Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195544.

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This dissertation explores the consequences of atmospheric dynamics for observations of substellar mass objects (SMOs). Discussed first is the growth of cloud particles of various compositions in brown dwarfs of different surface gravities and effective temperatures. The structure of these objects is calculated with a one-dimensional radiative transfer model. To determine particle sizes, the timescales for microphysical growth processes, including nucleation, coagulation, and coalescence, are compared to the timescale for gravitational sedimentation. The model also allows for sustained uplifting of condensable vapor in convective regions. The results show that particle sizes vary greatly over the range of objects studied. In most cases, clouds on brown dwarfs do not dominate the opacity. Rather, they smooth the emergent spectrum and partially redistribute the radiative energy. The focus then shifts to extrasolar giant planets (EGPs). Results are presented from a three-dimensional model of atmospheric dynamics on the transiting Jupiter-like planet HD 209458b. As a close-in orbiter (known as a “roaster”), HD 209458b is super-heated on its dayside. Due to tidal locking of the interior, the dayside hemisphere faces the star in perpetuity, which leads to very different dynamics than is seen on Jupiter. The flow is characterized by an eastward supersonic jet (u ∼ 4 km s⁻¹) extending from the equator to the mid-latitudes. Temperature contrasts are ∼ 500 K at the photosphere. At 220 mbar, winds blow the hottest regions downstream from the substellar point by ∼ 60°, with direct implications for the infrared light curve. These simulations are extended to the study of carbon chemistry in HD 209458b’s atmosphere by coupling the CO/CH₄ reaction kinetics to the dynamics. Disequilibrium results from slow reaction rates at low temperatures and pressures. Effective vertical quenching near the ∼ 3 bar level leads to uniformly high concentrations of CO at the photosphere, even in cool regions where CH₄ is strongly favored thermodynamically. Observations are underway to detect these signatures of meteorology on HD 209458b and similar planets.

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22

Sudarsky, David. "Theoretical spectra and atmospheres of extrasolar giant planets". Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280087.

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This work is a detailed study of extrasolar giant planet (EGP) atmospheres and spectra. Models representative of the full range of systems known today are included, from the extreme close-in EGPs to Jovian-like planets at large orbital radii. Using a self-consistent planar atmosphere code along with the latest atomic and molecular cross sections, cloud models, Mie theory treatment of grain scattering and absorption, and incident stellar fluxes, I produce an extensive set of theoretical EGP atmosphere models and emergent spectra. The emergent spectra of EGPs strongly depend upon their outer atmospheric chemical compositions, which in turn depend upon the run of temperature and pressure with atmospheric depth. Because of qualitative similarities in the compositions and spectra of objects within several broad temperature ranges, EGPs fall naturally into five groups, or composition classes. Such a classification scheme, however preliminary, brings a degree of order to the rich variety of EGP systems known to exist today. Generic models that represent the EGP classes, as well as a set of specific models for a number of important systems that have been detected, are provided. Furthermore, the effects on emergent EGP spectra of varying key parameters such as surface gravity, cloud particle sizes, orbital distance, etc. are modeled. A discussion of current and future ground-based and space-based missions to detect and characterize EGPs in light of theoretical spectral models is included to facilitate an understanding of which systems are most likely to be studied successfully.

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23

Koskinen, T. T. "The stability of short-period extrasolar giant planets". Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1444248/.

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A three-dimensional coupled thermosphere-ionosphere model for extrasolar giant planets (EXOTIM) has been developed. This is the first such model reported in the literature. This thesis contains an extensive description of the model and the methods adopted in modelling the different physical processes expected in the upper atmospheres and ionospheres of extrasolar giant planets. Modelling the upper atmosphere is important because the stability of the atmosphere against thermal evaporation is controlled by the conditions in the thermosphere. The thermosphere is heated by the absorption of EUV and X ray (XUV) radiation emitted by the host star. The radiation also ionises the neutral species in the upper atmosphere, which is expected to be composed mainly of molecular and atomic hydrogen, and atomic helium. Ionisation and subsequent photochemistry leads to the formation of the H+, Hf, H3", and He+ ions (and small quantities of HeH+). H3" emits strongly in the infrared and may act as a significant coolant in gas giant thermospheres. Assuming photochemical equilibrium, the absorption of XUV radiation and ion photochemistry were modelled in a self-consistent fashion. The 3D model can also simulate strong winds affecting the upper atmosphere, and account for both advection and diffusion of the neutral species around the planet. The results indicate that within 1.0 AU from a solar-type host star, the upper atmospheres of Jupiter-type EGPs can be substantially cooler and more stable than implied by studies that ignore the possibility of radiative (Hf) cooling. In this context, a limiting distance, or a stability limit, was identified for such EGPs that depends on the composition of the upper atmosphere and ionosphere, and within which the atmospheres of the planets undergo hydrodynamic escape. Under restricted conditions, this limit is located around 0.15 AU from a Sun-like host star. The model was also used to simulate a newly found transiting planet HD17156b, which orbits its host star on a highly eccentric orbit.

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24

Wilson, David M. "The search for transiting extrasolar planets with SuperWASP". Thesis, Keele University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443609.

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25

Safizadeh, Neda. "Detection of extrasolar planets via microlensing and occultation /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p3001275.

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26

Mengistie, Getachew Mekonnen. "Gravitational microlensing and the search for extrasolar planets". Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/9798.

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Includes bibliographical references.
This project is aimed at tackling binary gravitational microlensing events. Since the early conception of gravitational lensing before Einstein’s General Theory of Relativity, physicists and astronomers of the early 18th century speculated that light, if treated as particle, can be affected by gravitational field. Gravitational Microlensing is defined as a phenomenon occurring when light coming from a distant (source) star is bent by the gravitational field of an intervening mass (lens) creating multiple image of the source which cannot be resolved. In this project, We applied a model for binary lens microlensing events. We analysed data obtained from different observatories: PLAXET, which includes SAAO, Sutherland, Canopus and Perth observatories, OGLE, Danish Telescope, LaSilla. For the observed microlensing target OGLE-2011-BLG-265, analysis of the data using the program supplied by Keith Horne, using different minimization schemes and algorithms, I found best fit model to be a binary lens with mass ratio q = 0.0042 and separation of components is found to be u = 1.034 where in this case the separation falls under an intermediate binary lens topology. Finally, the deviation from the point-source point-lens microlensing events on the light curve and small mass ratio suggested a planetary system. I also calculated the time, tp, that the source needs to cross the diameter of the planet Einstein Ring radius, which is related to the mass ratio, and is found to be 3.30 days.

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27

Tan, Xianyu y 谭先瑜. "Characterizing the orbital and dynamical state of extrasolar multiple-planet systems with radial velocity measurements". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50162792.

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Extrasolar planetary surveys have discovered about 780 extrasolar planets and more than 100 multiple planetary systems to date, with the largest fraction of them being confirmed by the radial velocity detection method. Multiple planetary systems, especially those contain pairs of planets in mean-motion resonances, are particularly interesting because their current orbital architectures provide constraints for orbital evolution of planetary systems. Precisely determining the orbital and dynamical state of multiple planetary systems with radial velocity measurements is important. New results from an analysis of radial velocity data of the HD 82943 planetary system based on 10 years of measurements obtained with the Keck telescope is presented in this thesis. Previous studies have shown that the HD 82943 system has two planets that are likely in 2:1 MMR, with the orbital periods about 220 and 440 days (Lee et al. 2006). However, alternative fits that are qualitatively different have also been suggested, with the two planets in 1:1 resonance or the addition of a third planet possibly in a Laplace 4:2:1 resonance with the other two (Goździewski & Konacki 2006; Beaugé et al. 2008). Here based on the X^2 minimization method combined with parameter grid search, the orbital parameters and dynamical states of the qualitatively different types of fits have been investigated. The results support the coplanar 2:1 MMR configuration for this system and fits of the 1:1 resonance and the 3-planet Laplace resonance are ruled out according to X^2 statistic and dynamical instability. The inclination of the HD 82943 system is well constrained at about 20°C. The system contains two planets with masses of about 4.64 MJ and 4.66 MJ and orbital periods of about 219 and 442 days for the inner and outer planet, respectively. The best fit is dynamically stable with two resonance angles θ 1 = λ1 - 2λ2 + ϖ1 and θ 2 = λ1 - 2λ2 + ϖ 2 librating around 0°. Based on the best fit, the origin of the 2:1 MMR of the HD 82943 planetary system has been explored by N-body simulations with forced inward migration of the outer planet. This research has demonstrated the importance of dynamical fitting for multiple planetary systems with radial velocity measurements. It also fulfills the cases of planetary systems in mean-motion resonances such that more generic understanding of the orbital evolution of planetary systems can be obtained.
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Earth Sciences
Master
Master of Philosophy

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28

Lavvas, P. y T. Koskinen. "Aerosol Properties of the Atmospheres of Extrasolar Giant Planets". IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/626046.

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We use a model of aerosol microphysics to investigate the impact of high-altitude photochemical aerosols on the transmission spectra and atmospheric properties of close-in exoplanets, such as HD 209458 b and HD 189733 b. The results depend strongly on the temperature profiles in the middle and upper atmospheres, which are poorly understood. Nevertheless, our model of HD 189733 b, based on the most recently inferred temperature profiles, produces an aerosol distribution that matches the observed transmission spectrum. We argue that the hotter temperature of HD 209458 b inhibits the production of high-altitude aerosols and leads to the appearance of a clearer atmosphere than on HD 189733 b. The aerosol distribution also depends on the particle composition, photochemical production, and atmospheric mixing. Due to degeneracies among these inputs, current data cannot constrain the aerosol properties in detail. Instead, our work highlights the role of different factors in controlling the aerosol distribution that will prove useful in understanding different observations, including those from future missions. For the atmospheric mixing efficiency suggested by general circulation models, we find that the aerosol particles are small (similar to nm) and probably spherical. We further conclude that a composition based on complex hydrocarbons (soots) is the most likely candidate to survive the high temperatures in hot-Jupiter atmospheres. Such particles would have a significant impact on the energy balance of HD 189733 b's atmosphere and should be incorporated in future studies of atmospheric structure. We also evaluate the contribution of external sources to photochemical aerosol formation and find that their spectral signature is not consistent with observations.

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29

Fong, Wen-fai. "Extrasolar planet transit photometry at Wallace Astrophysical Observatory". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44460.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.
Includes bibliographical references (p. 42-43).
Extrasolar planet transit photometry is a relatively new astronomical technique developed over the past decade. Transit photometry is the measurement of a star's brightness as an orbiting planet passes in front of the star as seen from the Earth. Recently, members of MIT's Planetary Astronomy Lab (PAL) have launched an observing program for extrasolar planet transits at Wallace Astrophysical Observatory (WAO), which houses the 24-inch telescope used in this work. The purpose of this thesis is to enable students and faculty to easily perform transit photometry at WAO and assess the feasibility of transit photometry there. The PAL extrasolar planetary database currently has 36 planetary candidates, 23 of which are observable at WAO due to their positive declinations 6 (in the Northern celestial hemisphere). The maintenance of this database is described. Prediction methods used in Mathematica to determine when transits will occur at WAO for a given period of time are discussed. The transits at WAO are prioritized based on frequency of transit, transit depth and celestial location of parent stars, using the prediction period of 01-20-2008 to 05-30-2008. This prediction period is compared to four others spanning 2007-2009. These results suggest that the best planetary candidates at WAO for the fall are XO-3b, WASP-lb and HAT-P-6b and for the spring are HAT-P-3b, TrES-3 and XO-3b. A typical observing plan is produced based on the planetary candidate TrES-3, including finder charts for the highest frequency transiting planets in Spring 2008. Data reduction and analysis using either the standard IDL routine phot or the "Make_Lightcurve.nb" Mathematica notebook are described. A partial transit of XO2b taken at WAO is presented. Given WAO's recent upgrade by PAL along with the data presented here, the feasibility for successful extrasolar planet transit photometry projects at WAO is high.
by Wen-fai Fong.
S.B.

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30

Bond, Jade. "The Chemistry of Extrasolar Planetary Systems". Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194946.

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This work examines the chemical nature of extrasolar planetary systems, considering both the host star and any potential terrestrial planets located within the system. Extrasolar planetary host stars are found to be enriched over non-host stars in several r- and s-process elements. These enrichments, however, are in keeping with general galactic chemical evolution trends. This implies that host stars have not experienced any unusual chemical processing or pollution and that the observed enrichments are primordial in nature.When combined with detailed chemical models, the dynamical models of O'Brien et al. (2006) are found to produce terrestrial planets with bulk elemental abundances in excellent agreement with observed planetary values. This clearly indicates that the combination of dynamical and chemical modeling applied here is successfully reproducing the terrestrial planets of the Solar System to the first order. Furthermore, these planets are found to form with a considerable amount of water, negating the need for large amounts of exogenous delivery. Little dependence on the orbital properties of Jupiter and Saturn is observed for the main rock-forming elements due to the largely homogenous disk composition calculated.The same modeling approach is applied to known extrasolar planetary systems. Terrestrial planets were found to be ubiquitous, forming in all simulations. Generally, small (< 1ML) terrestrial planets are produced close to their host star with little radial mixing occurring. Planetary compositions are found to be diverse, ranging from Earth-like to refractory dominated and C-dominated, containing significant amounts of carbide material. Based on these simulations, stars with Solar elemental ratios are the best place to focus future Earth-like planet searches as these systems are found to produce the most Earthlike terrestrial planets which are located within the habitable zones of their systems and containing a significant amount of water. C-rich planets, although unusual, are expected to exist in >20% of known extrasolar planetary systems based on their host star photospheric compositions. These planets are unlike any body we have previously observed and provide an exciting avenue for future observation and simulation.

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31

Boccaletti, Anthony. "Recherche de planetes extrasolaires par la methode des speckles noirs". Nice, 1999. http://www.theses.fr/1999NICE5348.

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Depuis la decouverte de la premiere planete extrasolaire en 1995 par l'equipe de m. Mayor (mayor & queloz 1995), plusieurs exo-planetes ont ete detectees par des programmes de vitesses radiales. Bien que tres performante, la methode des vitesses radiales ne permet pas une determination exacte de la masse du compagnon. D'autres solutions sont donc necessaires pour etudier plus en detail ces exo-planetes. En particulier, l'imagerie apporte plus d'informations si le faible signal emis par la planete est directement detecte. Mais les contraintes d'imagerie sont importantes car : 1) le rapport d'intensite etoile/planete est eleve (10 9 en visible), 2) la separation angulaire est tres faible (0. 5 pour un jupiter a 10pc). Les techniques coronographiques permettent d'augmenter la dynamique mais pas suffisamment pour detecter des exo-planetes. En 1995, a. Labeyrie a propose la methode des tavelures noires combinant les capacites des optiques adaptatives et de l'interferometrie des tavelures pour permettre l'imagerie directe d'exo-planetes. Dans ce memoire, je presenterai la modelisation des tavelures noires et les simulations qui ont permis de caracteriser cette methode. Des etoiles binaires ont ete observees avec un prototype de coronographe, et des compagnons faibles (ecart de 4 magnitudes) ont pu etre detectes a moins de 0. 5 de l'etoile. Nous avons egalement demontre la faisabilite d'une observation speckles noirs en proche ir avec le systeme d'optique adaptative adonis, ou quelques etoiles binaires ont ete imagees. Je presente egalement une proposition d'instrument coronographique pour le telescope spatial ngst qui devrait permettre d'obtenir l'image d'exo-jupiter et meme d'exo-terre. Pour terminer, nous avons mene une etude preliminaire sur la coronographie en interferometrie en utilisant le principe de pupille densifiee (labeyrie 1996). On montre que l'image de planetes telluriques peut etre obtenue directement sur un interferometre spatial a 10 microns.

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32

Ciceri, Simona [Verfasser] y Thomas [Akademischer Betreuer] Henning. "Characterizing Transiting Extrasolar Planets / Simona Ciceri ; Betreuer: Thomas Henning". Heidelberg : Universitätsbibliothek Heidelberg, 2016. http://d-nb.info/1180610245/34.

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33

Berton, Alessandro. "Detecting extrasolar planets using IFS-based simultaneous differential imaging". [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:16-opus-70936.

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34

Thrastarson, Heidar Thor. "General circulation modelling of close-in extrasolar giant planets". Thesis, Queen Mary, University of London, 2011. http://qmro.qmul.ac.uk/xmlui/handle/123456789/2448.

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A large fraction of the extrasolar planets detected so far are giant planets that have such short orbital periods (a few days) that they are thought to be tidally-synchronised with the host star. Such orbits lead to permanent day/night sides on the planets and provide a forcing condition for atmospheric dynamics that is not present in the Solar System. The main subject of this thesis is to model the atmospheric dynamics of these close-in extrasolar giant planets, using an accurate three-dimensional general circulation model (GCM). Using the GCM, the primitive equations are numerically solved, with idealised forcing represented by Newtonian relaxation. A large number of simulations is performed to thoroughly explore the relevant physical and numerical parameter space. First, it is found that different initial flow states lead to markedly different flow and temperature distributions. This result is in contrast with the results or assumptions of many published studies, and underlines the fact that circulation models are currently unsuitable for quantitative predictions without better constrained, and well-posed, initial conditions. Second, the effects of artificial viscosity – particularly in relation to the thermal relaxation timescale – are studied. It is demonstrated that using a large range of thermal time scales, including very short ones ( 1 h), as is common in the literature, leads to dominant noise and/or excessively dissipated fields. Finally, variations of the strength of thermal forcing are studied. Distinct stationary or oscillatory states are identified for different sets of forcing parameters. In addition, multiple long lasting states are observed for a given forcing. Most of the states are characterised by a low number ( 4) of large-scale vortices and planetary waves, which exhibit a periodic time variability. The spatiotemporal variability can be important for observational studies, and provides a strong argument for making repeated measurements of a given planet.

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35

Burton, John Robert. "Ground-based investigations of the atmospheres of extrasolar planets". Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669663.

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In this thesis, I present three main results which demonstrate significant development in the field of exoplanet atmosphere detection and modelling. A model for estimating the distortion of hot-Jupiter exoplanets due to the gravitational attraction by the host star solely based on observable parameters of transiting systems. The most significant case of distortion is that of the exoplanet WASP-12b which shows a bulk density over-estimation of 12%. In order to investigate the systematic sources of error associated with ground-based observations, the secondary eclipse of the transiting hot- Jupiter WASP-19b was observed, and found to have an eclipse depth of O.88±O.19mmag based on a single observation. Whilst this does represent a significant result, the systematics present in the data support further observations to better constrain the depth, duration and timing of the secondary eclipse. The final result presented in this thesis is a pilot study of the technique of 'defocussed transmission spectroscopy', a method of observation which is designed to allow for the detection of elements in the atmospheres of transiting extra-solar planets from groundbased platforms. I present limits on the detectability of sodium in exoplanet atmospheres, and provide a detailed investigation into the systematics associated with this novel observing technique. I also make recommendations as to how future observations can be improved, and present a possible detection of sodium in the atmosphere of WASP-12b with an absorption depth of O.12±O.03%.

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36

Barton, Emma Jane. "Hot molecular line lists for extrasolar planets and industry". Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1508500/.

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This research is a composite of projects which have individually contributed new results to their respective subjects, whilst collectively contributing to the updating of the ExoMol database to include pressure broadening. This research also represents a successful collaboration between academia and industry. A combination of empirical and ab initio methods were used to compute accurate ro-vibrational line lists for sodium chloride and potassium chloride and refine line lists for carbon monosulphide. Hot line lists for hydrogen chloride, formaldehyde, ammonia and methane were assessed by comparison to high resolution laboratory spectra at temperatures relevant to industrial spectral studies and extrasolar planets. Hot and room temperature Fourier transform infrared spectra of ammonia have been analysed using a variational line list available from ExoMol and, where available, experimental energy levels. Over 5000 new line assignments have been made, providing over 3000 new experimental energies in the range 500 - 11,000 wavenumbers. In addition, an analysis of a room temperature spectrum in the region 9000 - 10,400 wavenumbers has been started. A combined analysis of assigned high resolution experimental spectra of methane available from peer reviewed sources using the MARVEL algorithm has been started. It is intended that the resulting compilation of verified experimental ro-vibrational energies will aid the analysis of hot methane spectra in the region 1000 - 6300 wavenumbers. Custom built pressure and temperature dependent absorption cross sections for water, carbon monoxide, carbon dioxide and ammonia were generated using ExoMol and HITEMP line lists for new spectral retrieval code τ-REx, to facilitate the unbiased analysis of extrasolar planetary spectra. Finally, the data requirements and challenges related to data usage of these separate projects are used to inform the implementation of pressure broadening in the ExoMol database.

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37

Christiaens, Valentín André. "Imaging of interactions between circumstellar disks and extrasolar planets". Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/168078.

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Doctor en Ciencias, Mención Astronomía en Cotutela con Universidad de Lieja
Se necesitan observaciones para restringir los mecanismos involucrados en el proceso de formación de planetas. Los discos circunestelares ricos en gas y polvo, llamados discos protoplanetarios, son el lugar esperado de nacimiento de los planetas. Esta tesis se aprovecha de la sinergia entre ALMA y los instrumentos de imagen de alto contraste (HCI) para estudiar la formación de planetas y la retroalimentación mutua planeta-disco en discos protoplanetarios con grandes huecos, llamados discos de transición. La primera parte de esta tesis está dedicada a la imagen de estos discos. En particular, se realizó un análisis detallado de las espirales encontradas en MWC 758 y HD 142527. Las espirales de MWC 758 son probablemente debidas a la presencia de dos compañeros, con uno de ellos posiblemente detectado dentro de la cavidad en base a nuestros datos. En el caso de HD 142527, las espirales del borde de la cavidad parecen ser, junto con otras características del disco, productos de la interacción dinámica entre la binaria y el disco. Las espirales frías a mayor escala vistas con ALMA podrían estar relacionadas con la inestabilidad gravitacional del disco o las sombras proyectadas por el disco interno inclinado. Para probar la hipótesis que los huecos grandes en los discos de transición se deben a la presencia de compañeros, se llevó a cabo una encuesta HCI de esos discos utilizando VLT/NACO en IR térmico, presentada en la segunda parte de esta tesis. Se implementaron códigos de reducción de datos que se utilizaron para buscar compañeros en todos los discos ya observados en esta encuesta. Hasta el momento, se han identificado cuatro candidatos compañeros (de 15 fuentes observadas), aunque se requiere seguimiento para confirmar que son verdaderos compañeros. También se presenta mi contribución a la detección de un compañero subestelar joven muy rojo en el disco de escombros de HD 206893. El potencial de los espectrógrafos de campo integral (IFS) para detectar y caracterizar compañeros de baja masa está investigado en la tercera parte de esta tesis. Se observó una muestra de cinco discos de transición usando VLT/SINFONI en infrarojo cercano. La combinación de imagen diferencial angular y espectral (ASDI) permitió suprimir las imperfecciones del halo estelar de manera eficaz y lograr altos contrastes. Se detectaron tres compañeros y dos sistemas con espirales. En particular, se detectó el compañero de baja masa HD 142527 B en la mayoría de los canales espectrales lo que permitió llevar a cabo una caracterización espectral detallada y estimar sus parámetros físicos. En conclusión, esta tesis provee nueva información sobre los discos de transición y el posible vínculo entre los grandes huecos y la presencia de compañeros. Un análisis similar al caso de HD 142527 se aplicará a los compañeros confirmados en nuestras encuestas para entender mejor las interacciones compañero-disco y la formación de planetas.
Este trabajo ha sido parcialmente financiado por CONICYT-PCHA/Doctorado Nacional/2016-21161112

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38

Kraus, Stefan, John D. Monnier, Michael J. Ireland, Gaspard Duchêne, Catherine Espaillat, Sebastian Hönig, Attila Juhasz et al. "Planet Formation Imager (PFI): science vision and key requirements". SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622530.

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The Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to similar to 100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the "Hill Sphere" of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs.

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39

Christiansen, Jessie Leigh Physics Faculty of Science UNSW. "A tale of two surveys: searching for extrasolar planets from Australia and Antarctica". Awarded By:University of New South Wales. Physics, 2007. http://handle.unsw.edu.au/1959.4/43629.

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The transit method of detecting extrasolar planets relies on the small periodic changes in the brightness of the planet's host star as the planet orbits between the observer and the star. Transiting planets are extremely useful discoveries due to the significant gain in information that can be obtained on the planet and its host star than extrasolar planets discovered with other methods. The field of transiting planets has matured rapidly in the last 5 years, particularly in the area of wide-field surveys. This thesis describes the results of two such surveys. The Vulcan South Antarctic Planet Finder was designed to exploit the conditions at the South Pole, which are ideal for a transit survey. Several hardware failures resulted in the acquisition of only a small amount of corrupted data on a single field. The University of New South Wales Extrasolar Planet Search is an ongoing transit survey using the 0.5-m Automated Patrol Telescope at Siding Spring Observatory, Australia. 25 fields were observed for 1-4 months each between 2004 October and 2007 May. Light curves were constructed for ~87,000 stars down to I= 14th magnitude, and from these 23 planet candidates were identified. Ten candidates were eliminated using higher spatial resolution archived images and online catalogue data. Eight were followed up with higher spatial resolution imaging and/or medium resolution spectroscopy and were determined to be eclipsing binaries. Five candidates remain that require additional observation to determine their nature. No planets have been confirmed in this data set thus far. The large sets of high precision light curves generated by transit surveys hold significant potential for additional data-mining. To demonstrate this, a variable star catalogue was compiled from the full data set. A total of 850 variable stars were identified, with 659 new discoveries. In the course of compiling this catalogue, the first example of a high-amplitude δ Scuti star in an eclipsing binary was identified. This represented the first opportunity for a dynamical mass measurement of a highamplitude δ Scuti star, and the system was studied comprehensively.

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40

Baines, Ellyn. "Inspection and characterization of exoplanet systems using the CHARA Array". unrestricted, 2007. http://etd.gsu.edu/theses/available/etd-08062007-165009/.

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Thesis (Ph. D.)--Georgia State University, 2007.
Title from file title page. Harold A. McAlister, committee chair; Todd J. Henry, Douglas R. Gies, Theo A. ten Brummelaar, Nikolaus Dietz, committee members. Electronic text ( 433 p. : ill.) : digital, PDF file. Description based on contents viewed Oct. 29, 2007. Includes bibliographical references (p. 184-194).

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41

Chan, Ka-ho y 陳嘉豪. "Numerical exploration of the probability of capture into the 3:1 mean motion resonance". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B4979971X.

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Mean-motion resonances (MMR) are frequently observed in extrasolar planetary systems. It is generally believed that the resonances result from the convergent migration of planets. The much larger number of systems near the 2:1 resonance compared to 3:1 resonance in both the radial velocity and the Kepler data is probably due to the difference in the capture behaviors of 2:1 and 3:1 resonances. To study the capture probability of the 3:1 resonance, numerical three-body integrations with forced migration have been used to examine the dependence of the capture probability on migration rate, planetary masses, and initial orbital eccentricities. First, the numerical results have been confirmed with analytic theory in the adiabatic limit (Borderies & Goldreich 1984) and numerical results of the Hamiltonian model beyond this limit (Mustill & Wyatt 2011) for both the interior and exterior resonances in the circular restricted three-body problem. Then, the numerical exploration of the restricted three-body problem (R3BP) has been extended to cases with non-zero planet eccentricity in the adiabatic limit. The capture probability decreases with increasing planet eccentricity at small test particle eccentricity but does not depend strongly on the planet eccentricity at large test particle eccentricity. Interestingly, the critical eccentricity of the planet, below which resonance capture is certain, is much larger than the critical eccentricity of test particle which was not expected. Finally, the numerical exploration has been extended to situations with different planetary mass ratio m1/m2. In the cases where both planets are initially on circular orbits, the critical migration rate for certain capture agrees with that of Quillen (2006) in the R3BP. However, it does not change monotonically with m1/m2 and peaks at m1/m2 = 1. For m1/m2 = 1, the resonance capture is certain when the eccentricities of the inner and outer planets are small and decreases as the eccentricities increase. In contrast, the capture probability is low when the eccentricities are small and the capture probability peaks at certain values of the eccentricities in the non-adiabatic limits. The capture probability as a function of planet eccentricities for mass ratios m1/m2 = 0.5 and 2 in the adiabatic limit has also been studied. The capture probability at m1/m2 = 2 shows similar behaviors with m1/m2 = 1 but the capture behaviors at m1/m2 = 0.5 are significantly different from the capture behaviors at m1/m2 = 1. This research has explored the probability of resonant capture in several new regimes, including the elliptical restricted three-body problem, comparable mass cases in the adiabatic limit and the equal mass case in the non-adiabatic limits. This work enhances our knowledge in the capture behaviors of 3:1 MMR in different limits and is useful in the future studies of the period ratio distribution in extrasolar planet systems.
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Physics
Master
Master of Philosophy

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42

Mustill, Alexander James. "The dynamics of planets and discs". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610345.

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43

Hamacher, Duane Willis Physics Faculty of Science UNSW. "A search for transiting extrasolar planets from the southern hemisphere". Publisher:University of New South Wales. Physics, 2008. http://handle.unsw.edu.au/1959.4/40943.

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To date, more than 300 planets orbiting stars other than our sun have been discovered using a range of observing techniques, with new discoveries occuring monthly. The work in this thesis focused on the detection of exoplanets using the transit method. Planets orbiting close to their host stars have a roughly 10 per cent chance of eclipsing (transiting) the star, with Jupiter?sized planets causing a one per cent dip in the flux of the star over a few hours. A wealth of orbital and physical information on the system can be extracted from these systems, including the planet density which is essential in constraining models of planetary formation. To detect these types of planets requires monitoring tens of thousands of stars over a period of months. To accomplish this, we conduct a wide-field survey using the 0.5-meter Automated Patrol Telescope (APT) at Siding Spring Observatory (SSO) in NSW, Australia. Once candidates were selected from the data?set, selection criteria were applied to separate the likely planet candidates from the false?positives. For this thesis, the methods and instrumentation used in attaining data and selecting planet candidates are discussed, as well as the results and analysis of the planet candidates selected from star fields observed from 2004?2007. Of the 65 planet candidates initially selected from the 25 target fields observed, only two were consistent with a planet transit. These candidates were later determined to be eclipsing binary stars based on follow up observations using the 40-inch telescope, 2.3-m telescope, and the 3.9-m Anglo-Australian Telescope, all located at SSO. Additionally, two planet candidates from the SuperWASP-North consortium were observed on the 40-inch telescope. Both proved to be eclipsing binary stars. While no planets were found, our search methods and results are consistent with successful transit surveys targeting similar fields with stars in a similar magnitude range and using similar methods.

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44

Dittmann, Jason A. "Observing Extrasolar Planets at the University of Arizona's Kuiper Telescope". Thesis, The University of Arizona, 2010. http://hdl.handle.net/10150/146800.

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45

Morgan, Rhonda Michelle. "Achromatic nulling beam combiner for the detection of extrasolar planets". Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279844.

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Nulling stellar interferometry may enable the discovery of earth-like planets around other stars. In nulling mode, the zero order fringe is destructive and on axis, thus canceling light from a bright source and detecting dimer off-axis features. To create deep on-axis nulls, the phase must be shifted half a wave achromatically over a broad band. The phase shift is created by adding optical path thickness with dielectric plates. Plates of different materials can balance dispersion. The nulling solutions found for TPF (infrared) and for SIM (visible) are promising. This dissertation describes the implementation of a nulling beam combiner test bed and presents data characterizing its performance. Although the implementation was limited so that a broad band null of 10E-4 was not attained, the test bed revealed the extreme challenges of this technique and provided very valuable lessons that will enable future implementations to be successful and more precise. The nulling beam combiner testbed was implemented in the laboratory as a Michelson interferometer with the goal of achieving a stabilized, l0E-4 null over a spectral region from 600 nm to 800 nm. The beam combiner system has three tiers of control. Tier 1 controls phase achromaticity by tilting optical plates and is a static control loop. Tier 2 sweeps through the white light fringe and then searches for the null as the air path drifts over minutes. Tier 3 stabilizes the null with a 300 hertz servo loop. A scheme for active control of the optical thicknesses was developed. The phase as a function of wavelength was measured by performing PSI on a spectrally dispersed fringe. The phase was fit to a model to solve for the optical thicknesses. The optical thicknesses were then adjusted to match the ideal thicknesses of an optimized solution. This process of measuring and adjusting the optical thicknesses is performed iteratively to achromatize the phase. The stabilizing servo loop sensed on a grey fringe at a short wavelength. At the shorter wavelength, the fringe was 90 degrees out of phase with the main pass band resulting in a grey fringe. The grey fringe intensity is more sensitive to OPD changes.

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46

Alsubai, Khalid. "Wide angle search for extrasolar planets by the transit method". Thesis, St Andrews, 2008. http://hdl.handle.net/10023/521.

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47

Fjällmyr, Lennart. "En bibliometrisk kartläggning av det astronomiska/astrofysikaliska forskningsområdet ”extrasolar planets”". Thesis, Högskolan i Borås, Institutionen Biblioteks- och informationsvetenskap / Bibliotekshögskolan, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-19862.

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The purpose of this study was to bibliometrically investigate and describe the research area called “extrasolar planets”. The research questions were: Which authors were mostly cited within the area when the first authors (and their co-authors) were considered? Which authors were found in most co-occurrences? Did particular author collaborations emerge?To which institutions were most authors affiliated and did the size of the institution have an influence on whether an author was cited?What was the geographic distribution of authors and institutions and were there any patterns of collaboration?Did the image of dominating institutions and countries depend on the viewpoint?How applicable was Lotka’s law on the collected data? The data was collected from citation lists in documents from the database Arxiv.org. The documents were extracted by using the search term “extrasolar planets”. By using citation analysis and the method a)”first author counting”, complimented by the method b)”fractional counting” used on a material screened by method a), for accrediting publications to authors and countries, an image of the research area was depicted. Method b) was also used for extracting information about author collaboration and geographic distributions. The most quoted first author, also found in most co-occurrences, was attached to the largest institution, located in USA. Most quoted authors, almost 60%, were attached to USA. However, the results were inconclusive when the viewpoints were changed. Apart from the fact that 57.8% of the quoted documents originated from 9.5% of the first authors, Lotka’s law was not applicable.

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48

Gallardo, José. "Physics of low mass stars, brown dwarfs and extrasolar planets". Lyon, École normale supérieure (sciences), 2007. http://www.theses.fr/2007ENSL0412.

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Weldrake, David Thomas Frederick. "Giant planets and variable stars in globular clusters /". View thesis entry in Australian Digital Theses Program, 2005. http://thesis.anu.edu.au/public/adt-ANU20050616.191315/index.html.

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Grether, Daniel Andrew Physics Faculty of Science UNSW. "Statistical analyses of extrasolar planets and other close companions to nearby stars". Awarded by:University of New South Wales. School of Physics, 2006. http://handle.unsw.edu.au/1959.4/29182.

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We analyse the properties of extrasolar planets, other close companions and their hosts. We start by identifying a sample of the detected extrasolar planets that is minimally affected by the selection effects of the Doppler detection method. With a simple analysis we quantify trends in the surface density of this sample in the Msini-period plane. A modest extrapolation of these trends puts Jupiter in the most densely occupied region of this parameter space, thus suggesting that Jupiter is a typical massive planet rather than an outlier. We then examine what fraction of Sun-like (~ FGK) stars have planets. We find that at least ~25% of stars possess planets when we limit our analysis to stars that have been monitored the longest and whose low surface activity allow the most precise radial velocity measurements. The true fraction of stars with planets may be as large as ~100%. We construct a sample of nearby Sun-like stars with close companions (period < 5 years). By using the same sample to extract the relative numbers of stellar, brown dwarf and planetary companions, we verify the existence of a very dry brown dwarf desert and describe it quantitatively. Approximately 16% of Sun-like stars have close companions more massive than Jupiter: 11% +- 3% are stellar, <1% are brown dwarf and 5% +- 2% are giant planets. A comparison with the initial mass function of individual stars and free-floating brown dwarfs, suggests either a different spectrum of gravitational fragmentation in the formation environment or post-formation migratory processes disinclined to leave brown dwarfs in close orbits. Finally we examine the relationship between the frequency of close companions and the metallicity of their Sun-like hosts. We confirm and quantify a ~4 sigma positive correlation between host metallicity and planetary companions. In contrast we find a ~2 sigma anti-correlation between host metallicity and the presence of a stellar companion. Upon dividing our sample into FG and K sub-samples, we find a negligible anti-correlation in the FG sub-sample and a ~3 sigma anti-correlation in the K sub-sample. A kinematic analysis suggests that this anti-correlation is produced by a combination of low-metallicity, high-binarity thick disk stars and higher-metallicity, lower-binarity thin disk stars.

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