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1
Marquart, Thomas. "Star-forming Dwarf Galaxies : Internal motions and evolution." Doctoral thesis, Uppsala universitet, Observationell astrofysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-181481.
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The study of dwarf galaxies is important in order to better understand the physics of the young universe and how larger galaxies form and evolve. In this work we focus on Blue Compact Galaxies (BCGs) which havemuch enhanced star formation (starbursts), causing blue colours and strong emission line spectra. Investigating of the inner motions of BCGs provides a means for determining masses and understanding what triggered the current starburst. We have used the Very Large Telescope to perform challenging observations of the stellar motions in several BCGs, as seen in the near-infrared Ca-triplet absorption lines. By comparing these to the kinematics of the ionized interstellar medium, we were able to look into the role of feeback from stellar winds and supernova explosions, as well as further strengthen the notion that the merging of galaxies plays an important role. Spatially resolved spectroscopy can yield information about the 3D-structure of galaxies. We have used a Fabry-Perot interferometer to study the kinematics of the interstellar medium in two samples of galaxies, each containing about twenty objects. We find strong indications for ongoing galaxy mergers that correlate well with the strength of the star-formation activity. Furthermore, by estimating dynamical masses, BCGs are shown to be on average not dynamically supported by rotation. In addition, we have used data from the Sloan Digital Sky Survey to study the frequency of starbursts in the local universe and the connection to their descendants. We selected starbursts by the strength of emission in H-alpha, the first Balmer recombination line, and post-starbursts by the strength of absorption in H-delta. These are indicators of currently ongoing and recent, on the order of 100 Myr, star-formation, respectively. By modelling the stellar populations we derive ages and masses and can establish a link between starbursts and postbursts in a time sequence. We find that starbursts are active on a 100 Myr timescale but are rare objects in the local universe.
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Caddy, Robert V. "Time Series Photometry of the Symbiotic Star V1835 Aql and New Variable Stars in Aquila." Bowling Green State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1525438143057776.
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Simunovic, Muñoz Mirko [Verfasser], and Eva K. [Akademischer Betreuer] Grebel. "The Blue Straggler Star Populations in Galactic Globular Clusters / Mirko Simunovic Muñoz ; Betreuer: Eva K. Grebel." Heidelberg : Universitätsbibliothek Heidelberg, 2017. http://d-nb.info/1180739531/34.
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Simunovic, Muñoz Mirko Verfasser], and Eva K. [Akademischer Betreuer] [Grebel. "The Blue Straggler Star Populations in Galactic Globular Clusters / Mirko Simunovic Muñoz ; Betreuer: Eva K. Grebel." Heidelberg : Universitätsbibliothek Heidelberg, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-225846.
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Kumari, Nimisha. "Spatially-resolved studies of nearby star-forming galaxies." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283605.
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Spatially-resolved studies of nearby star-forming galaxies are essential to understand various physical and chemical phenomena at play in the interstellar medium in the galaxies, and consequently to obtain a comprehensive picture of galaxy formation and evolution. In this thesis, I perform spatially-resolved analyses of chemical abundances and star-formation in nearby star-forming galaxies - blue compact dwarf galaxies (BCDs) and spiral galaxies. I map various properties of H II regions and the surrounding gas within three BCDs, using integral field spectroscopic (IFS) data from the Gemini Multi-Object Spectrograph-North. While answering questions related to chemical homogeneity, ionisation mechanisms and stellar populations within BCDs, I address more profound issues, which go beyond the characterisation of studied BCDs and aim to explain global phenomena with broader implications. The BCD NGC 4449 hosts a metal-poor central star-forming region, which I explain by various scenarios related to the interplay between star-formation, metal-distribution and gas dynamics within galaxies. The BCD NGC 4670 shows an unusual negative relationship between the nitrogen-to-oxygen ratio and oxygen abundance at spatially-resolved scales. I explore this relation with chemical evolution models and by comparison to other star-forming galaxies and suggest that nitrogen enrichment, variations in star-formation efficiency or hydrodynamical effects may be responsible for the observed relation. For another BCD, SBS 1415+437, the spatially-resolved abundances on average agree with the integrated abundance, implying that low-redshift spatially-resolved results may be directly compared with unresolved high-redshift results. I study spiral galaxies to address long-standing issues related to the reliability of metallicity calibrators and the Schmidt Law of star-formation. Using IFS data of twenty-four spiral galaxies taken with the Multi-Unit Spectroscopic Explorer, I find that the current strong-line metallicity calibrators for H II regions are unsuitable for regions dominated by diffuse ionised gas (DIG). I devise new recipes for estimating the metal-content of the DIG. For another set of nine spiral galaxies, I use multi-wavelength data to show that the spatially-resolved Schmidt relation is very sensitive to the consideration of diffuse background, which is a component unrelated to the current star-formation. Removal of this component from the SFR tracers and the atomic gas results in similar local and global Schmidt relation. To conclude, the spatially-resolved analyses presented in this thesis have led to discoveries and further questions, which I will address in my ongoing and future works.
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Huenemoerder, David, Lidia M. Oskinova, Richard Ignace, Wolf-Rainer Hamann, Nobert S. Schulz, Hilding Neilson, and Tomer Shenar. "A Deep X-ray Look at a Very Massive Star: HETGS Spectroscopy of the Blue Hypergiant Cyg OB2-12 (HIP 101364)." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etsu-works/2698.
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We have obtained a Chandra/HETGS spectrum of one of the most massive and luminous stars in the Galaxy: the blue hypergiant Cyg OB2-12 (HIP 101364, spectral type B3 Ia+). This is the first measurement at high resolution of X-ray spectral lines in a blue hypergiant and allows comparison of X-ray properties between massive stars at different but related evolutionary stages: O-type supergiants, luminous blue variables, Wolf-Rayet stars, and blue hypergiants stars. The new data provide a look at how the most massive stars shed mass during their pre-supernova evolution. We find that In Cyg OB2-12 the resolved Si and Mg lines are broadened by about 1000 km/s (FWHM). The lines, however, do not show appreciable centroid shifts (/s), which would be much larger for canonical moderately thick winds (~500 km/s). The He-like Mg XI lines show evidence of photo-excitation, implying a wind origin close to the UV-bright photosphere. The spectrum also indicates relatively high temperature plasma, up to 22 MK (1.9 keV), showing significant continuum and emission lines below 5A (above 2.5 keV). Hence, at first glance, the spectrum resembles neither an O-star thick wind, nor a magnetically confined (narrow-line) plasma. We will present more detailed wind models using both X-ray and UV spectra to constrain fundamental physical parameters of this star.
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Mosqueira, Vargas Rodrigo. "Reposición de Escuela Blue Star, Lo Espejo: espacios educativos contemporáneos en el marco de la reforma educacional." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/143927.
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Ashley, Trisha L. "The HI Chronicles of LITTLE THINGS Blue Compact Dwarf Galaxies." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1441.
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Star formation occurs when the gas (mostly atomic hydrogen; H I) in a galaxy becomes disturbed, forming regions of high density gas, which then collapses to form stars. In dwarf galaxies it is still uncertain which processes contribute to star formation and how much they contribute to star formation. Blue compact dwarf (BCD) galaxies are low mass, low shear, gas rich galaxies that have high star formation rates when compared to other dwarf galaxies. What triggers the dense burst of star formation in BCDs but not other dwarfs is not well understood. It is often suggested that BCDs may have their starburst triggered by gravitational interactions with other galaxies, dwarf-dwarf galaxy mergers, or consumption of intergalactic gas. However, there are BCDs that appear isolated with respect to other galaxies, making an external disturbance unlikely.
Here, I study six apparently isolated BCDs from the LITTLE THINGS1sample in an attempt to understand what has triggered their burst of star formation. LITTLE THINGS is an H I survey of 41 dwarf galaxies. Each galaxy has high angular and velocity resolution H I data from the Very Large Array (VLA) telescope and ancillary stellar data. I use these data to study the detailed morphology and kinematics of each galaxy, looking for signatures of starburst triggers. In addition to the VLA data, I have collected Green Bank Telescope data for the six BCDs. These high sensitivity, low resolution data are used to search the surrounding area of each galaxy for extended emission and possible nearby companion galaxies.
The VLA data show evidence that each BCD has likely experienced some form of external disturbance despite their apparent isolation. These external disturbances potentially seen in the sample include: ongoing/advanced dwarf-dwarf mergers, an interaction with an unknown external object, and external gas consumption. The GBT data result in no nearby, separate H I companions at the sensitivity of the data. These data therefore suggest that even though these BCDs appear isolated, they have not been evolving in isolation. It is possible that these external disturbances may have triggered the starbursts that defines them as BCDs.
1Local Irregulars That Trace Luminosity Extremes, The H I Nearby Galaxy Survey; https://science.nrao.edu/science/surveys/littlethings
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Adamo, Angela. "Super Star Clusters in Blue Compact Galaxies : Evidence for a near-infrared flux excess and properties of the starburst phase." Doctoral thesis, Stockholms universitet, Institutionen för astronomi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-52681.
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Luminous Blue compact galaxies (BCGs) are metal-poor actively star-forming systems, characterised by bright ultraviolet and blue luminosities. Hubble Space Telescope high-resolution data have revealed that the luminous star-forming knots in these galaxies are composed of hundreds of young massive star clusters. In this work we present a systematic study of the star cluster populations in BCGs with important implications for the formation history of their host systems. The studied galaxies show recently increased star formation rates and a high fraction of massive clusters, probably as a result of minor/major merger events. The age distributions have a peak of cluster formation at only 3 - 4 Myr, unveiling a unique sample of clusters still partially embedded. A considerable fraction of clusters (30 - 50 %), mainly younger than 10 Myr, shows an observed flux excess between 0.8 and 2.2 μm. This so-called near-infrared (NIR) excess is impossible to reproduce even with the most recent spectral synthesis models (that include a self-consistent treatment of the photoionized gas). The origin of the NIR excess, which still remains unexplained, challenges our understanding of the cluster formation process under extreme conditions. The results achieved in this work have produced important insights into the cluster formation process in BCGs. We suggest that the BCG environment has most likely favoured the compression and collapse of giant molecular clouds into compact massive star clusters. The cluster formation efficiency (i.e., the fraction of star formation happening in star clusters) in BCGs is higher than the reported 8 - 10 %, for quiescent spirals and local star-forming galaxies. Luminous BCGs have a cluster formation efficiency comparable to luminous infrared galaxies and spiral starburst nuclei (the averaged value is about 30 %), suggesting an important role of the merger event in the cluster formation.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Accepted. Paper 5: Manuscript. Paper 6: Manuscript.
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Goldberg-Morse, Hannah Elizabeth. "It's Hard to Be Sant in the City: How Bhindranwale and the Sikh Militants Invoked the Sikh Past to Rationalize Violence in Post-Partition Punjab." Scholarship @ Claremont, 2014. http://scholarship.claremont.edu/cmc_theses/851.
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1984’s Operation Blue Star, an Indian Army maneuver to rid the Sikh Golden Temple of militants, shocked the world. Bullet holes riddled the temple’s façade in the operation’s aftermath, and the global Sikh community was outraged at the desecration of the site. How did the political conflict in Punjab escalate to this point? What were the factors behind the Sikh militant movement, and how did the militants rationalize their activities, considered by some as rampant terrorism? This thesis examines the circumstances surrounding the rise to arms of the Punjabi Sikh militants and the religious influences of their movement. Identifying how themes of the Sikh past, particularly those of communal identity, martyrdom, and martial tradition, were repurposed and employed by militant Sikhs to ground their violence in Sikh tradition and practice, the thesis finds that leaders of the movement, like Sant Bhindranwale, created rhetorical bridges to the Sikh past and embedded in the community a sense of participating in a greater, cosmic war. There exists a tendency among scholars to overlook the religious elements of the movement in order to assign political, economic or sociological roots to the conflict, but religion was a primary factor in the conflict, as demonstrated through the words and actions of the militants themselves. This research adopts a sociotheological approach to religious studies, drawing upon framework by Mark Juergensmeyer, Émile Durkheim and Pierre Bourdieu, among others, to frame the influence of the Sikh past on the militants’ own plane of reference.
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Loubser, Susan Ilani. "Analysis and interpretation of astrophysical optical emission-line spectra / Susan Ilani Loubser." Thesis, North-West University, 2005. http://hdl.handle.net/10394/84.
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This study consists of a quantitative optical emission-line analysis of spectra
from five blue compact galaxies (Zw 0855, Mrk 1267, II Zw 33, Tol 2
& Tol 3), as well as a qualitative analysis of spectra from two galactic H
II regions (NGC 3603 & NGC 3576). It serves a two-fold purpose: first, to
understand the CCD reduction, spectra extraction and different nebular analysis
methods, together with their applications and limitations, preparatory
to studies using the Southern African Large Telescope (SALT) and second,
to extend current star formation related research to include extragalactic
starburst galaxies. The observations were carried out using the 1.9m telescope
(equipped with a grating spectroscope and CCD detector) of the South
African Astronomical Observatory (SAAO), during the period 1 to 7 March
2005. The necessary CCD data reduction, spectra extraction, wavelength
and flux calibration, Doppler shift as well as reddening correction procedures
were performed before the emission lines were identified and measured. A full
nebular analysis, including temperature, density, metallicity (oxygen abundance)
and other chemical abundance determinations, was performed on the
blue compact galaxies (BCGs). Two different nebular analysis packages viz.
IRAF's nebular and SNAPwere used, with all the results well within the
range of values expected for metal poor BCGs. Recommendations on the different methods and their applications are made.Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2006.
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Leanza, Silvia. "Ricerca di evolved blue straggler stars in M80." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17903/.
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Questo elaborato di tesi si inserisce nel contesto della ricerca di stelle Evolved Blue Straggler Stars (E-BSS) in ammassi globulari Galattici.
Le BSS sono ritenute essere significativamente più massicce delle stelle che tipicamente popolano un ammasso stellare. Questi oggetti sono facilmente identificabili durante la loro fase di bruciamento dell'idrogeno, al contrario è impossibile distinguerli fotometricamente, in modo certo, dalle altre stelle di minore massa del sistema che li ospita durante le fasi evolutive successive.
In questo lavoro è stato applicato il metodo spettroscopico utilizzato da Ferraro et al. (2016) per identificare una E-BSS nell'ammasso globulare 47 Tuc e basato sul confronto tra le abbondanze chimiche derivate da righe spettrali neutre e ionizzate. Tale metodo permette di ricavare una stima della gravità a superficiale e, quindi, della massa stellare.
In particolare, sono stati analizzati spettri ad alta risoluzione, acquisiti con lo spettrografo ad alta risoluzione UVES, di un campione 13 stelle candidate E-BSS dell'ammasso globulare M80 situate nella regione del CMD tra l'HB e l'attacco dell'AGB.
I principali risultati di quest'analisi hanno mostrato che nel campione analizzato non vi sono E-BSS particolarmente massicce e, inoltre, hanno evidenziato una sottostima sistematica dell'abbondanza chimica ricavata da righe neutre in tutte le stelle di post-RGB, mentre le righe ionizzate risultano il diagnostico più u robusto ed affidabile per derivare le abbondanze chimiche.
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Smith, Nathan. "The isolation of luminous blue variables: on subdividing the sample." OXFORD UNIV PRESS, 2016. http://hdl.handle.net/10150/621726.
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A debate has arisen concerning the fundamental nature of luminous blue variables (LBVs) and their role in stellar evolution. While Smith & Tombleson proposed that their isolated environments indicate that LBVs must be largely the product of binary evolution, Humphreys et al. have recently expressed the view that the traditional single-star view still holds if one appropriately selects a subsample of LBVs. This paper finds the claim of Humphreys et al. to be quantitatively unjustified. A statistical test of 'candidate' as opposed to 'confirmed' LBVs shows no significant difference (<1 sigma) between their environments. Even if the sample is further subdivided as proposed, the three most luminous LBVs are spatially dispersed similar to late O-type dwarfs, which have much longer median lifetimes than expected for classical LBVs. The lower luminosity LBVs have a distribution associated with red supergiants (RSGs), but these RSGs are dominated by stars of 10-15 M-circle dot initial mass, with much longer lifetimes than expected for those lower luminosity LBVs. If one's view is restricted to the highest luminosity LBVs, then the appropriate comparison is with early O-type stars that are their presumed progenitors; when this is done, it is clear that even the high-luminosity LBVs are more dispersed than expected. Humphreys et al. also suggest that velocities of LBVs support the single-star view, being inconsistent with runaways. A quantitative analysis of the radial velocity distribution of LBVS in M31 and M33 contradicts this; modest runway speeds expected from mass gainers in binary evolution are consistent with the observed velocities, although the data lack the precision to discriminate.
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Ciannella, Vincenza. "La popolazione delle Blue Straggler Stars negli ammassi globulari." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Gli AG sono sistemi dinamicamente attivi e sono gli unici a sperimentare tutti i processi di dinamica conosciuti, costituiscono per questo motivo una fornace molto efficiente nello generare oggetti cosiddetti esotici.
Le BSS sono gli oggetti più luminosi e più blu del turnoff della sequenza principale. La loro formazione avviene attraverso due principali meccanismi: le collisioni stellari sono il meccanismo predominante negli ambienti con una densità alta ed il trasferimento di massa è attivo soprattutto negli ambienti con una densità bassa. Un importante ruolo svolto dalle BSS emerge attraverso lo studio della loro distribuzione radiale, infatti attraverso i diversi profili di distribuzione si risale all’età dinamica degli ammassi che le contengono. Per questo motivo le BSS costituiscono dei perfetti indici dell’evoluzione dinamica degli ammassi.
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Santucci, Giulia. "Abbondanze chimiche delle Blue Straggler Stars dell'ammasso aperto NGC 188." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11477/.
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My Thesis work is aimed at searching for evidence of CO-depletion in the atmosphere of these objects. To this end, I am analyzing high-resolution spectra recently acquired with the spectrograph HDS at the Subaru Telescope. The global sample is composed of 5 BSSs with
hot WD companions, 3 additional binary BSSs with no a significant far-UV excess, and one "normal" stars (along the RGB star) needed for comparison. The analysis will
provide us with the surface chemical abundances (especially of C and O) of the target stars. The final goal is to verify the expected {chemical signature} and put constraints on its characteristic time scale (for instance, a positive detection in the 5 BSSs with hot companions and a non-detection in the other 3 binary BSSs would imply
that CO-depletion is a transient phenomenon, lasting approx 300 Myr only). The analysis will also provide us with the rotational velocities of each target, thus allowing to investigate their kinematical properties and shed new light on their evolutionary path.
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Rugheimer, Sarah M. "Hues of Habitability: Characterizing Pale Blue Dots Around Other Stars." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467184.
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A wide range of potentially rocky transiting planets in the habitable zone (HZ) have been detected by Kepler as well as ground-based searches. The spectral type of the host star will influence our ability to detect atmospheric features with future space and ground based missions like JWST, GMT and E-ELT. For my thesis, I present a complete suit of stellar models with a stellar effective temperature ranging from Teff = 2300K to Teff = 7000K, sampling the entire FGKM stellar type range, for modeling extrasolar planets. I also have a grid of model atmospheres for an Earth-analogue planet orbiting stars and derive remotely detectable spectral atmospheric features.
The UV emission from a planet's host star dominates the photochemistry and thus the resultant observable spectral features. Using the latest UV spectra obtained by Hubble as well as IUE, I model Earth-like planets for a wide range of host stars. I detail the results of activity on the primary detectable atmospheric features that indicate habitability on Earth, namely: H2O, O3, CH4, N2O and CH3Cl. I model the emergent spectra of Earth-analogue planets orbiting our grid of FGKM stars in the VIS/NIR (0.4 - 4 microns) and the IR (5 - 20 microns) range in accordance with future mission design concepts like JWST and direct detection missions like HDST/LUVOIR in the more distant horizon. We also model the amount of UV flux reaching the surface of Earth-like planets at various geological epochs ranging from a pre-biotic world through the rise of oxygen and for Earth-like planets orbiting FGKM stars at equivalent stages of evolution.Astronomy
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Smith, Nathan, Jose H. Groh, Kevin France, and Richard McCray. "Ultraviolet spectroscopy of the blue supergiant SBW1: the remarkably weak wind of a SN 1987A analogue." OXFORD UNIV PRESS, 2017. http://hdl.handle.net/10150/624061.
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The Galactic blue supergiant SBW1 with its circumstellar ring nebula represents the best known analogue of the progenitor of SN 1987A. High-resolution imaging has shown H alpha and infrared structures arising in an ionized flow that partly fills the ring's interior. To constrain the influence of the stellar wind on this structure, we obtained an ultraviolet (UV) spectrum of the central star of SBW1 with the Hubble Space Telescope Cosmic Origins Spectrograph. The UV spectrum shows none of the typical wind signatures, indicating a very low mass-loss rate. Radiative transfer models suggest an extremely low rate below 10(-10) M-circle dot yr(-1), although we find that cooling time-scales probably become comparable to (or longer than) the flow time below 10(-8) M-circle dot yr(-1). We therefore adopt this latter value as a conservative upper limit. For the central star, the model yields T-eff = 21 000 +/- 1000 K, log(g(eff)) = 3.0, L similar or equal to 5 x 10(4) L-circle dot, and roughly Solar composition except for enhanced N abundance. SBW1' s very low mass-loss rate may hinder the wind's ability to shape its nebula and to shed angular momentum. The spin-down time-scale for magnetic breaking is more than 500 times longer than the age of the ring. This, combined with the star's slow rotation rate, constrains merger scenarios to form ring nebulae. The mass-loss rate is at least 10 times lower than expected from mass-loss recipes, without any account of clumping. The physical explanation for why SBW1' s wind is so weak presents an interesting mystery.
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Andronov, Nikolay I. "Evolution of close binary stars with application to cataclysmic variables and Blue Stragglers." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1126025974.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xii, 190 p.; also includes graphics (some col.). Includes bibliographical references (p. 181-190). Available online via OhioLINK's ETD Center.
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Pattee, Julie Anne. "A ceiling of blue: swimming pools, movie stars and manifest destiny." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=96752.
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This thesis explores the relationship between the social history and the filmic history of the swimming pool. The history of the swimming pool and the history of the movies wove themselves together during the first half of the twentieth century. By 1950, the image of the swimming pool and the image of the movie star were connected in the social imaginary. Discourses about gender, health, discipline and the body were moulded by the architectural environment of the swimming pool, when the movies translated the image of the swimming pool, they carried these ideas along with them. These ideas affected the formation of modern subjectivities. This thesis attempts to demonstrate one of the means by which a particular set of ideas infiltrated the collective psycheCette thèse examine le rapport entre l'histoire sociale et l'histoire filmique de la piscine. Elle tente de démonter le moyen par lequel une tendance particulier c'est inflirté dans la psyché collective. L'histoire de la piscine et l'histoire du cinema se sont entrelacé au cours de la prèmiere moitier du vingtieme sciècle. Par l'année 1950, l'image de la piscine et l'image de la vedette étaient liés dans l'imagination sociale. Les discours au sujet de sexe, la santé, la discipline et le corps étaient façonné par l'environment architecturale de la piscine. Losque le cinéma traduit l'image de la piscine, il emporte ces idées avec. Ces idées affectent la formation des subjectivités moderne. Cette thèse tente de dèmontrer le moyen par lequel une tendance particulier c'est infiltré dans la psyché collective.
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Rafiul, Islam Mirza Sharoz. "Spectral Results for the Blue Plume Stars in Canis Major Overdensity." UKnowledge, 2015. http://uknowledge.uky.edu/physastron_etds/32.
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We present distances and kinematics and look at the possible populations for the blue plume (BP) stars in the Canis Major Overdensity (CMa). We conducted a medium resolution spectral survey on the BP stars (N=303) in CMa (centered at l = 238° ; b = -8°) using the data from AAOmega Spectrograph. We used a modified version of the Statistics-sensitive Non-linear Iterative Peak-clipping (SNIP) algorithm to normalize our fluxed absorption spectra. After determining the radial velocities from measurements of strong absorption features for the stars we use a Bayesian analysis of spectral feature strengths and photometric colors to determine Teff, Logg and [Fe/H]. Our procedure makes use of grid for model synthetic spectra computed using SPECTRUM with Atlas9 model atmospheres and Kurucz model colors. We determine the absolute magnitude using the stellar parameters and BaSTI isochrones and compute distances and ages for the BP stars.
Our analysis of the BP stars indicates Teff ranging from 6500K to 8000K, metallicity ranging from 0.0 to -1.0 with an average of -0.5. We found for this temperature range that the surface gravity of the stars could not be well constrained. From the spatial and kinematics results we found that most of the stars are thick disk stars with a small mixture of thin disk stars. The stars are most likely a mixture of thick disk blue stragglers and normal A-type stars preferentially seen to greater depths due to the low dust extinction in this location of the Galaxy.
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Murphy, Simon J., Maxwell Moe, Donald W. Kurtz, Timothy R. Bedding, Hiromoto Shibahashi, and Henri M. J. Boffin. "Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binaries." OXFORD UNIV PRESS, 2018. http://hdl.handle.net/10150/627133.
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The orbital parameters of binaries at intermediate periods (10(2)-10(3) d) are difficult to measure with conventional methods and are very incomplete. We have undertaken a new survey, applying our pulsation timing method to Kepler light curves of 2224 main-sequence A/F stars and found 341 non-eclipsing binaries. We calculate the orbital parameters for 317 PB1 systems (single-pulsator binaries) and 24 PB2s (double-pulsators), tripling the number of intermediate-mass binaries with full orbital solutions. The method reaches down to small mass ratios q approximate to 0.02 and yields a highly homogeneous sample. We parametrize the mass-ratio distribution using both inversion and Markov-Chain Monte Carlo forward-modelling techniques, and find it to be skewed towards low-mass companions, peaking at q approximate to 0.2. While solar-type primaries exhibit a brown dwarf desert across short and intermediate periods, we find a small but statistically significant (2.6 sigma) population of extreme-mass-ratio companions (q < 0.1) to our intermediate-mass primaries. Across periods of 100-1500 d and at q > 0.1, we measure the binary fraction of current A/F primaries to be 15.4 per cent +/- 1.4 per cent, though we find that a large fraction of the companions (21 per cent +/- 6 per cent) are white dwarfs in post-mass-transfer systems with primaries that are now blue stragglers, some of which are the progenitors of Type Ia supernovae, barium stars, symbiotics, and related phenomena. Excluding these white dwarfs, we determine the binary fraction of original A/F primaries to be 13.9 per cent +/- 2.1 per cent over the same parameter space. Combining our measurements with those in the literature, we find the binary fraction across these periods is a constant 5 per cent for primaries M-1 < 0.8 M-circle dot, but then increases linearly with log M-1, demonstrating that natal discs around more massive protostars M-1 greater than or similar to M-1(circle dot) become increasingly more prone to fragmentation. Finally, we find the eccentricity distribution of the main-sequence pairs to be much less eccentric than the thermal distribution.
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Iemmi, Erik. "L'ammasso globulare NGC 6362 e la sua sequenza di Blue Straggler Stars." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18447/.
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Questo lavoro di tesi si inserisce nel contesto della caratterizzazione delle popolazioni stellari e dello stato dinamico degli ammassi globulari. Questi sistemi sperimentano molteplici processi di dinamica interna che alterano progressivamente le loro proprietà fisiche e il loro contenuto stellare. In particolare, sono l'habitat naturale in cui possono essere generati oggetti esotici come le Blue Straggler Stars, un tipo di stelle che si formano dalla collisione diretta di due o più astri di sequenza principale, o per il trasferimento di massa in un sistema binario, dove almeno una delle due stelle sta ancora bruciando idrogeno nel nucleo. Essendo stelle più massicce della media, le Blue Stragglers risentono del processo di attrito dinamico, che tende a farle progressivamente migrare verso le zone più interne dell'ammasso. La loro distribuzione radiale, quindi, è un eccellente indicatore dello stato dinamico del sistema ospite (e.g., Ferraro et al. 2012).
In questo lavoro viene analizzato, dal punto di vista fotometrico, NGC 6362, uno degli ammassi globulari di più piccola massa nel quale è stata osservata la presenza di popolazioni multiple, caratterizzate da diverso contenuto degli elementi leggeri (Dalessandro et al. 2014, Mucciarelli et al. 2016, Massari et al. 2017). Il fatto che queste popolazioni siano spazialmente mescolate tra loro suggerisce che NGC 6362 sia un ammasso dinamicamente evoluto (Dalessandro et al. 2014). L'obiettivo principale di questa tesi è quello di utilizzare le Blue Stragglers per fornire una verifica indipendente dello stato avanzato di evoluzione dinamica del sistema. Per questo scopo sono stati utilizzati dati fotometrici ottenuti a partire da osservazioni effettuate con il canale UVIS della camera WFC3 e con il canale WFC della camera ACS del telescopio spaziale Hubble Space Telescope, per un totale di 19 immagini in 6 filtri diversi, dal vicino ultravioletto al vicino infrarosso.
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Clewley, Lee. "Determining the mass of the Milky Way using blue horizontal branch stars." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397180.
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Lovisi, Loredana <1985>. "Chemical and kinematical properties of Blue Straggler stars in Galactic globular clusters." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5209/.
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Blue straggler stars (BSSs) are brighter and bluer (hotter) than the main-sequence (MS) turnoff and they are known to be more massive than MS stars.Two main scenarios for their formation have been proposed:collision-induced stellar mergers (COL-BSSs),or mass-transfer in binary systems (MT-BSSs).Depleted surface abundances of C and O are expected for MT-BSSs,whereas no chemical anomalies are predicted for COL-BSSs.Both MT- and COL-BSSs should rotate fast, but braking mechanisms may intervene with efficiencies and time-scales not well known yet,thus preventing a clear prediction of the expected rotational velocities.Within this context,an extensive survey is ongoing by using the multi-object spectrograph FLAMES@VLT,with the aim to obtain abundance patterns and rotational velocities for representative samples of BSSs in several Galactic GCs.A sub-population of CO-depleted BSSs has been identified in 47 Tuc,with only one fast rotating star detected.For this PhD Thesis work I analyzed FLAMES spectra of more than 130 BSSs in four GCs:M4,NGC 6397,M30 and ω Centauri.This is the largest sample of BSSs spectroscopically investigated so far.Hints of CO depletion
have been observed in only 4-5 cases (in M30 and ω Centauri),suggesting either that the majority of BSSs have a collisional origin,or that the CO-depletion is a transient phenomenon.Unfortunately,no conclusions in terms
of formation mechanism could be drawn in a large number of cases,because of the effects of radiative levitation. Remarkably,however,this is the first time that evidence of radiative levitation is found in BSSs hotter than 8200 K.Finally, we also discovered the largest fractions of fast rotating BSSs ever observed in any GCs:40% in M4 and 30% in ω Centauri.While not solving the problem of BSS formation,these results provide invaluable information about the BSS physical properties,which is crucial to build realistic models of their evolution.
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Raso, Silvia. "Le Blue Straggler Stars e le popolazioni multiple in quattro ammassi globulari galattici." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11468/.
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In questo elaborato viene presentato lo studio fotometrico di quattro ammassi globulari galattici.
I target di questa Tesi fanno parte della HST UV Legacy Survey degli ammassi globulari galattici (Piotto et al. 2015). Nell'ambito di questa survey sono stati osservati, in modo omogeneo, 57 ammassi globulari galattici con il telescopio spaziale Hubble e la camera WFC3, in tre bande fotometriche ultraviolette e blu.
Un dataset così composto è adatto a numerosi scopi, tra cui lo studio delle popolazioni calde come le BSS e delle popolazioni multiple.
Sono stati selezionati quattro ammassi particolarmente popolosi e tra i più densi del campione, allo scopo di mettere a punto indicatori di evoluzione dinamica e comprendere il ruolo di quest'ultima sulle proprietà delle popolazioni multiple presenti nei sistemi selezionati.
Lo studio dell'evoluzione dinamica è stato effettuato tramite la distribuzione radiale delle BSS (Blue Straggler Stars), che è stato dimostrato esserne un efficiente indicatore (Ferraro et al. 2012). I risultati ottenuti evidenziano chiaramente che tutti gli ammassi selezionati si trovano in fasi avanzate di evoluzione dinamica, come suggerito dall'alta densità che li caratterizza.
Anche lo studio delle proprietà delle popolazioni multiple, ovvero sottopopolazioni con differenti abbondanze chimiche di elementi leggeri, la cui presenza è stata recentemente osservata negli ammassi globulari, è stato effettuato tramite lo studio della loro distribuzione radiale. Tra i quattro casi analizzati, soltanto M 15 ha mostrato una separazione significativa tra le distribuzioni radiali delle due popolazioni.
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Oskinova, Lidia M., David P. Huenemoerder, Wolf-Rainer Hamann, Tomer Shenar, A. A. C. Sander, Richard Ignace, H. Todt, and R. Hainich. "On the Binary Nature of Massive Blue Hypergiants: High-resolution X-Ray Spectroscopy Suggests That Cyg OB2 12 is a Colliding Wind Binary - IOPscience." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/2688.
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The blue hypergiant Cyg OB2 12 (B3Ia+) is a representative member of the class of very massive stars in a poorly understood evolutionary stage. We obtained its high-resolution X-ray spectrum using the Chandra observatory. PoWR model atmospheres were calculated to provide realistic wind opacities and to establish the wind density structure. We find that collisional de-excitation is the dominant mechanism depopulating the metastable upper levels of the forbidden lines of the He-like ions Si xivand Mg xii. Comparison between the model and observations reveals that X-ray emission is produced in a dense plasma, which could reside only at the photosphere or in a colliding wind zone between binary components. The observed X-ray spectra are well-fitted by thermal plasma models, with average temperatures in excess of 10 MK. The wind speed in Cyg OB2 12 is not high enough to power such high temperatures, but the collision of two winds in a binary system can be sufficient. We used archival data to investigate the X-ray properties of other blue hypergiants. In general, stars of this class are not detected as X-ray sources. We suggest that our new Chandra observations of Cyg OB2 12 can be best explained if Cyg OB2 12 is a colliding wind binary possessing a late O-type companion. This makes Cyg OB2 12 only the second binary system among the 16 known Galactic hypergiants. This low binary fraction indicates that the blue hypergiants are likely products of massive binary evolution during which they either accreted a significant amount of mass or already merged with their companions.
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Santucci, Rafael Miloni. "Caracterização de estrelas azuis tardias no campo galáctico." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/14/14131/tde-20062013-155903/.
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As estrelas azuis tardias (blue straggler stars ou estrelas BS) são estrelas de sequência principal que apresentam um aparente atraso evolutivo em relação às suas vizinhanças. Elas foram identificadas inicialmente na sequência principal de aglomerados globulares acima do ponto de turnoff no diagrama HR. Desde então, têm sido encontradas em todos os ambientes estelares: aglomerados abertos e globulares, galáxias anãs próximas e entre as estrelas de campo na Galáxia. O principal objetivo deste trabalho é construir uma grande amostra de estrelas BS no campo galáctico. Para tanto, métodos de separação desses objetos de estrelas BHB foram comparados com critérios de seleção que envolvem parâmetros atmosféricos estimados pelo SEGUE Stellar Parameter Pipeline (SSPP). Tal procedimento permitiu incluir também estrelas com magnitudes g maiores que 18, antes excluídas pelos métodos tradicionais para objetos com razão sinal-ruído menores que 9. Os métodos apresentados neste trabalho permitiram a seleção de uma amostra de 8001 candidatas a estrelas BS que foram analisadas cinematicamente, através de suas velocidades radiais. Verificou-se que aproximadamente um quinto dessa amostra (cerca de 1500 objetos) possui características que a associa à corrente de Sagitário, sugerindo uma origem extragaláctica para tais objetos.Blue straggler stars (BSSs) are main sequence stars that exhibit an apparent evolutionary delay over the region where they are found in the HR diagram. They were initially identified in the main sequence of globular clusters above the turnoff point. Since then, they have been found in many different stellar environments: globular and open clusters, near dwarf galaxies, and also in the field of the Galaxy. The main goal of this work is to build a large sample of BSSs in the galactic field region. In order to accomplish this task, classical methods of separation of BSS from BHB stars were compared with proposed restrictions based on their atmospheric parameters, which are estimated by the SEGUE Stellar Parameter Pipeline (SSPP). The latter procedure allowed to include stars with magnitudes g greater than 18, not handled by traditional methods when signal-noise ratio is smaller than 9. The selection methods gathered a sample of 8001 BS stars. These stars were kinematically analyzed through their radial velocities. The results suggest that many of them (about 1500) can have extragalactic origin, associated with Sagittarius stream.
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Smith, Nathan, and Keivan G. Stassun. "The Canonical Luminous Blue Variable AG Car and Its Neighbor Hen 3-519 Are Much Closer than Previously Assumed." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/624732.
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The strong mass loss of Luminous Blue Variables (LBVs) is thought to play a critical role in massive-star evolution, but their place in the evolutionary sequence remains debated. A key to understanding their peculiar instability is their high observed luminosities, which often depends on uncertain distances. Here we report direct distances and space motions of four canonical Milky Way LBVs-AG Car, HR. Car, HD. 168607, and (candidate) Hen. 3-519-from the Gaia first data release. Whereas the distances of HR. Car and HD. 168607 are consistent with previous literature estimates within the considerable uncertainties, Hen. 3-519 and AG Car, both at similar to 2 kpc, are much closer than the 6-8 kpc distances previously assumed. As a result, Hen. 3-519 moves far from the locus of LBVs on the Hertzsprung-Russell diagram, making it a much less luminous object. For AG Car, considered a defining example of a classical LBV, its lower luminosity would also move it off the S Dor instability strip. Lower luminosities allow both AG Car and Hen. 3-519 to have passed through a previous red supergiant phase, lower the mass estimates for their shell nebulae, and imply that binary evolution is needed to account for their peculiarities. These results may also impact our understanding of LBVs as potential supernova progenitors and their isolated environments. Improved distances will be provided in the Gaia second data release, which will include additional LBVs. AG Car and Hen. 3-519 hint that this new information may alter our traditional view of LBVs.
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Revell, Stephanie. "Female flânerie and the nexus of the star in Leni Riefenstahl's Das blaue Licht (1932)." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44353.
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This paper seeks to contribute to the search for the female flâneur in Leni Riefenstahl's figure of Junta in the 1932 mountain film Das blaue Licht. It will use the literature from and of Weimar modernity and feminist cultural theory and contributes to the project of “understanding female subjectivity” in women's studies and cultural studies. Here understanding is informed by the search for the female flâneur in modernity, and female subjectivity is understood as a visible and “spectacular” one consisting in the occupation and manipulation of modernity's images. I will introduce the phrase “nexus of the star” to incorporate the various terms and discussions surrounding this experience, and explain how female flânerie informs its definition. This paper acknowledges the term flâneuse as traditionally used to refer to a potential female flâneur, but does not engage with it here. This paper also acknowledges the use of such phrases as “modern man” which are only used and intended in their original contexts signifying the “modern subject.”
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Andruet, Davide. "La popolazione di Blue Straggler Stars in due ammassi globulari della Grande Nube di Magellano." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9650/.
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Le Blue Straggler Stars (BSS) sono la popolazione di oggetti esotici piu' comune e numerosa negli ammassi globulari. Nel diagramma colore-magnitudine le BSS definiscono una sequenza più brillante e blu del punto di turn-off della Sequenza Principale, simulando una popolazione più giovane delle stelle dell'ammasso.
Osservazioni hanno dimostrato che le BSS hanno una massa significativamente più grande (1.2-1.7 Msun) di quella delle stelle di un ammasso globulare. Per questa proprietà, la distribuzione radiale delle BSS e' un utile strumento per tracciare empiricamente lo stato di evoluzione dinamica degli ammassi stellari.
Il lavoro di tesi si è concentrato sullo studio della popolazione di BSS di due ammassi globulari della Grande Nube di Magellano: NGC2257 e NGC1754. Applicando metodi di indagine già usati per sistemi stellari della Via Lattea, abbiamo derivato le eta' dinamiche di questi due sistemi e le abbiamo confrontate con stime teoriche.
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Bindi, Chiara. "Analisi della segregazione di massa in ammassi globulari mediante Blue Straggler Stars e binarie fotometriche." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
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Gli ammassi globulari sono i sistemi stellari più popolosi, vecchi e densi nella Galassia. Il rilassamento a due
corpi ne guida l'evoluzione dinamica a lungo termine: oggetti più pesanti "scivolano" verso le regioni
centrali (segregazione di massa), mentre i meno massicci sono spinti su orbite più esterne. La dinamica
interna influenza oggetti di qualsiasi massa e può essere studiata attraverso l'analisi di Blue Straggler Stars
(BSS) e binarie.
La tesi ha come obiettivo quello di studiare lo stato di evoluzione dinamica di tre ammassi globulari
Galattici (NGC5053, NGC6218 e NGC6981) attraverso l'analisi della distribuzione radiale di BSS e binarie.
E' stata utilizzata un'opportuna combinazione di data-set: l'Hubble Space Telescope per le regioni centrali e
più dense e telescopi da terra per quelle più periferiche, permettendo di campionare l'intera estensione
radiale con adeguata risoluzione spaziale e di studiare sia le sequenze più brillanti che quelle più deboli.
L'analisi del lavoro di tesi rivela che i tre ammassi studiati sono caratterizzati da stati di evoluzione dinamica
differente: NGC5053 è un sistema dinamicamente giovane, poichè le due popolazioni sono distribuite come
le stelle di riferimento; in NGC6218, entrambe le distribuzioni sono bimodali, suggerendo un'età dinamica
intermedia, in cui gli effetti di segregazione hanno agito fino a distanze intermedie dal centro; NGC6981 è il
sistema dinamicamente più evoluto, avendo distribuzioni monotone decrescenti, la dinamica interna ha
modificato le orbite degli oggetti massicci su tutta l'estensione dell'ammasso.
Il buon accordo tra i risultati ottenuti mediante BSS e binarie evidenziano l'efficacia dell'uso della
distribuzione radiale di BSS ("orologio dinamico") come potente indicatore dell'evoluzione dinamica dei
sistemi stellari.
I risultati della tesi forniscono ulteriore supporto all'idea che la popolazione di BSS sia il risultato
dell'evoluzione di sistemi binari, soprattutto in ammassi poco densi.
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Billi, Alex. "Velocità rotazionali di stelle Blue Straggler nell'ammasso globulare NGC 3201." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25358/.
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Le Blue Straggler Stars (BSS) sono stelle che si trovano lungo il prolungamento della sequenza principale del diagramma colore-magnitudine degli ammassi globulari (GC). La loro origine è legata all'interazione tra stelle, e sono un fondamentale tracciante della dinamica interna dei GC. Lo studio delle loro velocità di rotazione (vsini) rappresenta ancora una sfida, poiché sono necessari spettri ad alta risoluzione ed alto rapporto segnale-rumore, operazione non sempre facile a causa della bassa luminosità di questi oggetti. Le misure di rotazioni di BSS disponibili fino ad oggi suggeriscono una possibile correlazione tra la percentuale di rotatori veloci (FR) e alcune proprietà fisiche dell'ammasso che le ospita: più l'ammasso è denso e meno FR sono presenti. Simunovic & Puzia, 2014 (SP14) presentano le rotazioni di un campione di 37 BSS dell'ammasso NGC 3201, trovando una percentuale di FR inferiore a quella aspettata in base alla correlazione appena discussa. In questo lavoro di tesi sono state osservate 77 BSS e 104 stelle giganti rosse membre dell'ammasso NGC 3201. L'obiettivo è di misurare le velocità rotazionali delle BSS membre dell'ammasso per verificare la suddetta correlazione. I principali risultati sono i seguenti: la distribuzione delle vsini ottenute dall'analisi è diversa da quella di SP14. La distribuzione delle vsini di NGC 3201 è molto più simile a quella cumulativa degli ammassi loose, rispetto a quella degli ammassi più densi. Utilizzando varie threshold si è
visto che, all'aumentare dei valori di threshold, la differenza tra la percentuale di FR di NGC 3201 e quelle degli altri ammassi di simile concentrazione, in funzione dei parametri strutturali dei GC, diminuisce sempre di più. Le BSS FR di NGC 3201 risultano maggiormente concentrate al centro dell'ammasso rispetto alle BSS con rotazione inferiore.
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Kollegger, Thorsten [Verfasser], Reinhard [Akademischer Betreuer] Stock, and Christoph [Akademischer Betreuer] Blume. "Search for upsilons in heavy-ion collisions with the STAR detector / Thorsten Kollegger. Gutachter: Reinhard Stock ; Christoph Blume." Frankfurt am Main : Univ.-Bibliothek Frankfurt am Main, 2005. http://d-nb.info/1046853600/34.
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Hallakoun, N., (许偲艺) S. Xu, D. Maoz, T. R. Marsh, V. D. Ivanov, V. S. Dhillon, M. C. P. Bours, et al. "Once in a blue moon: detection of ‘bluing' during debris transits in the white dwarf WD 1145+017." OXFORD UNIV PRESS, 2017. http://hdl.handle.net/10150/625505.
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The first transiting planetesimal orbiting a white dwarf was recently detected in K2 data of WD 1145+017 and has been followed up intensively. The multiple, long and variable transits suggest the transiting objects are dust clouds, probably produced by a disintegrating asteroid. In addition, the system contains circumstellar gas, evident by broad absorption lines, mostly in the u' band, and a dust disc, indicated by an infrared excess. Here we present the first detection of a change in colour of WD 1145+017 during transits, using simultaneous multiband fast-photometry ULTRACAM measurements over the u'g'r'i' bands. The observations reveal what appears to be 'bluing' during transits; transits are deeper in the redder bands, with a u' - r' colour difference of up to similar to-0.05 mag. We explore various possible explanations for the bluing, including limb darkening or peculiar dust properties. 'Spectral' photometry obtained by integrating over bandpasses in the spectroscopic data in and out of transit, compared to the photometric data, shows that the observed colour difference is most likely the result of reduced circumstellar absorption in the spectrum during transits. This indicates that the transiting objects and the gas share the same line of sight and that the gas covers the white dwarf only partially, as would be expected if the gas, the transiting debris and the dust emitting the infrared excess are part of the same general disc structure (although possibly at different radii). In addition, we present the results of a week-long monitoring campaign of the system using a global network of telescopes.
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Getreuer, Melanie Lynn. ""From the Depths Of The Earth, We, The Men Underground, Will Start Singing": Globalization and Blue-Collar Workers in Post-Communist Poland and Russia." Thesis, Boston College, 2004. http://hdl.handle.net/2345/444.
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Thesis advisor: Paul T. ChristensenCompares globalization's impact on blue-collar workers in Poland and Russia, asking two major questions: Is conventional wisdom about globalization's impact on labor accurate in the Polish and Russian contexts? What shape has Poland and Russia's reintegration into the globalized system taken since the collapse of communism? Following the collapse of communism from 1989 to 1991, there was a great international effort to reintegrate Poland and Russia (and the whole of the former Soviet Union more generally) into the global system. Now, more than ten years later, there is some doubt about the success of this mission. Clearly, Poland and Russia are in different positions vis a vis the international system. While Poland is a member of NATO and has just joined the EU, Russia continues to struggle to find its place globally. It is part of the CIS and has obserer status in the WTO, but remains outside NATO and is conflicted about its relationship with its neighbors. The two countries in certain respects, then, represent the extremes on a scale of post-communist global reintegration. Labor, in turn, has been an historically important force for establishing and consolidating democracy. Therefore, it warrents scrutiny
Thesis (BA) — Boston College, 2004
Submitted to: Boston College. College of Arts and Sciences
Discipline: International Studies
Discipline: College Honors Program
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Jansson, Hanna. "Förutsättningar för implementering av mångfunktionella grönblå strukturer : En kvalitativ studie av Hyllie i Malmö stad." Thesis, Linköpings universitet, Tema Miljöförändring, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166689.
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Stadsplanerare står inför framtida utmaningar med fortsätt förtätning av städer och ökade risker i och med klimatförändringarna. För att få plats för alla samhällsfunktioner som behövs i de kompakta städerna, däribland klimatanpassningsåtgärder, finns det ett behov av mångfunktionella lösningar. Grönblå infrastruktur har en mångfunktionell karaktär och kan användas för att kombinera hantering av översvämningar, värmeböljor och andra samhällsfunktioner i samma lösningar. Trots att dessa fördelar är tydliga i forskningen kvarstår det svårigheter i att implementera lösningarna i praktiken. Syftet med denna uppsats är att studera förutsättningar för implementering av mångfunktionella grönblå lösningar. Detta har gjorts i tidigare studier, men inte med fokus på planering av nya stadsdelar, vilket kommer vara fokus i denna studie där stadsdelen Hyllie i Malmö används som studieobjekt. Analysen grundas på kvalitativa semistrukturerade intervjuer med tjänstemän från olika avdelningar på kommunen som är involverade i stadsplaneringen. Resultatet visar att de främsta förutsättningarna för implementering är väl fungerande samverkan, kunskap, regleringsmöjligheter, finansiella resurser och politiskt stöd för prioritering av grönblå strukturer. För att förbättra dessa förutsättningar finns det möjligheter för kommunen att utveckla samverkan inom organisationen och med utomstående aktörer och gå mot mer förenade mål och gemensamt ansvar. En annan möjlighet är att genom arbetet i pilotprojekt utveckla nya lösningar för reglering samt öka kunskapen om grönblå strukturer. Här är utmaningen att integrera erfarenheterna i projekten i kommunens kärnarbete.Urban planners will have to handle future challenges due to the densification of cities and the increased risks resulting from climate change. In order to accommodate all the community functions needed in the compact cities, including climate adaptation measures, there is a need for multifunctional solutions. Green-blue infrastructure is multifunctional in its nature and can be used to combine management of floods, heat waves and other community functions in the same solutions. Although these benefits are clear in research, difficulties remain in implementing the solutions in practice. The aim of this paper is to study the prerequisites for implementing multifunctional green-blue solutions. This has been done in previous studies, but not with a focus on planning new neighbourhoods, which will be the focus of this study where the Hyllie district in Malmö is used as a study object. The analysis is based on qualitative semi-structured interviews with officials from various departments of the municipality who are involved in urban planning. The results show that the main prerequisites for implementation are well-functioning collaboration, knowledge, regulatory opportunities, financial resources and political support for prioritizing green-blue structures. To improve these conditions, there are opportunities for the municipality to develop collaboration within the organization and with external actors and move towards more unified goals and shared responsibility. Another possibility is to work with pilot projects to develop new solutions for regulation and to increase the knowledge of green-blue structures. Here, the challenge is to integrate the experience of the projects into the municipality's core work.
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Ekanayake, Gemunu. "Determination of Stellar Parameters through the Use of All Available Flux Data and Model Spectral Energy Distributions." UKnowledge, 2017. http://uknowledge.uky.edu/physastron_etds/44.
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Basic stellar atmospheric parameters, such as effective temperature, surface gravity, and metallicity plays a vital role in the characterization of various stellar populations in the Milky Way. The Stellar parameters can be measured by adopting one or more observational techniques, such as spectroscopy, photometry, interferometry, etc. Finding new and innovative ways to combine these observational data to derive reliable stellar parameters and to use them to characterize some of the stellar populations in our galaxy is the main goal of this thesis.
Our initial work, based on the spectroscopic and photometric data available in literature, had the objective of calibrating the stellar parameters from a range of available flux observations from far-UV to far-IR. Much effort has been made to estimate probability distributions of the stellar parameters using Bayesian inference, rather than point estimates.
We applied these techniques to blue straggler stars (BSSs) in the galactic field, which are thought to be a product of mass transfer mechanism associated with binary stars. Using photometry available in SDSS and GALEX surveys we identified 85 stars with UV excess in their spectral energy distribution (SED) : indication of a hot white dwarf companion to BSS. To determine the parameter distributions (mass, temperature and age) of the WD companions, we developed algorithms that could fit binary model atmospheres to the observed SED. The WD mass distribution peaks at 0.4M , suggests the primary formation channel of field BSSs is Case-B mass transfer, i.e. when the donor star is in red giant phase of its evolution. Based on stellar evolutionary models, we estimate the lower limit of binary mass transfer efficiency β ~ 0.5.
Next, we have focused on the Canis Major overdensity (CMO), a substructure located at low galactic latitude in the Milky Way, where the interstellar reddening (E(B-V )) due to dust is significantly high. In this study we estimated the reddening, metallicity distribution and kinematics of the CMO using a sample of red clump (RC) stars. The averageE(B-V)(~0.19)is consistent with that measured from Schlegel maps (Schlegal et.al. 1998). The overall metallicity and kinematic distribution is in agreement with the previous estimates of the disk stars. But the measured mean alpha element abundance is relatively larger with respect to the expected value for disk stars.
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Kreuzer, Simon [Verfasser], Ulrich [Akademischer Betreuer] Heber, and Ulrich [Gutachter] Heber. "Revisiting the MMT HVS survey - A comprehensive spectral and kinematic analysis of faint blue stars in the Galactic halo / Simon Kreuzer ; Gutachter: Ulrich Heber ; Betreuer: Ulrich Heber." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2021. http://d-nb.info/1230631577/34.
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Cerqui, Valeria. "Ammassi globulari di Bulge attraverso l'ottica adattiva multi-coniugata di GeMS/GSAOI: il caso di NGC 6638." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22441/.
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Il Bulge rappresenta la prima componente massiva della Via Lattea ad essersi formata. Per tale motivo, comprendere la sua struttura ed evoluzione è di grande importanza per descrivere i processi di formazione ed evoluzione della Galassia. Gli ammassi globulari sono degli strumenti estremamente utili per tracciare le proprietà del Bulge.
Questo lavoro di Tesi si inserisce nell’ambito di una survey fotometrica volta ad indagare la popolazione di tali strutture attraverso una combinazione di dati provenienti da strumenti che utilizzano sistemi di ottica adattiva e operanti dallo spazio, che garantiscono immagini di elevata qualità e risoluzione. In particolare, l’oggetto di studio dell’elaborato è l’ammasso globulare NGC 6638. I dati infrarossi sono stati acquisiti tramite il sistema GeMS/GSAOI, mentre quelli ottici con il telescopio spaziale HST. Sfruttando questo data-set è stato possibile caratterizzare la popolazione stellare di NGC 6638 e le sue proprietà strutturali e dinamiche con un livello di accuratezza e definizione mai raggiunto prima. In particolare, l'analisi dei CMD ottico-infrarossi decontaminati attraverso lo studio dei moti propri e corretti per effetti di reddening differenziale, ha reso possibile la prima stima accurata dell'età di questo sistema, che risulta essere in buon accordo con l'età degli altri GCs di Bulge. Inoltre, lo studio della popolazione di stelle variabili del sistema ha permesso l'identificazione di 6 nuove candidate RR-Lyrae e di un oggetto esotico che mostra un'intensa modulazione di luminosità e probabilmente parte di un sistema binario. L'analisi del profilo di densità e l’utilizzo delle BSSs hanno inoltre evidenziato che NGC 6638 è un ammasso relativamente poco denso e caratterizzato da un’evoluzione dinamica intermedia.
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Vale, Anna. "The Effects of Binocular Vision Impairment on Adaptive Gait. The effects of binocular vision impairment due to monocular refractive blur on adaptive gait involving negotiation of a raised surface." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4931.
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Impairment of stereoacuity is common in the elderly population and is found to be a risk factor for falls. The purpose of these experiments was to extend knowledge regarding impairment of binocular vision and adaptive gait. Firstly using a 3D motion analysis system to measure how impairment of stereopsis affected adaptive gait during a negotiation of a step, secondly by determining which clinical stereotest was the most reliable for measuring stereoacuity in elderly subjects and finally investigating how manipulating the perceived height of a step in both binocular and monocular conditions affected negotiation of a step. In conditions of impaired stereopsis induced by acutely presented monocular blur, both young and elderly subjects adopted a safety strategy of increasing toe clearance of the step edge, even at low levels of monocular blur (+0.50DS) and the effect was greater when the dominant eye was blurred. The same adaptation was not found for individuals with chronic monocular blur, where vertical toe clearance did not change but variability of toe clearance increased compared to full binocular correction. Findings indicate stereopsis is important for accurately judging the height of a step, and offers support to epidemiological findings that impaired stereoacuity is a risk for falls. Poor agreement was found between clinical stereotests. The Frisby test was found to have the best repeatability. Finally, a visual illusion that caused a step to be perceived as taller led to increased toe elevation. This demonstrates a potential way of increasing toe clearance when stepping up and hence increase safety on stairs.
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Chiziţcaia, Oxana. "Vývoj konceptu strategie "Modrých oceánů"." Master's thesis, Vysoká škola ekonomická v Praze, 2017. http://www.nusl.cz/ntk/nusl-261961.
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The subject of this thesis are two terms, start-ups and strategies blue oceans. The aim is therefore to realize characteristic development of the strategy and the concept of start-up and subsequent analysis of the key success factors of start-ups, in correspondence to the strategy. Output objective is to formulate recommendations on the business segment, investors. The above primary terms are initially defined and subsequently integrated in terms of the practical analysis selected start-ups, which is also based design of this work. The work was divided into two parts, theoretical and practical. The theoretical part identifies and traces the development of the strategic concept at the time, according to the primary authors of publications strategy. Then I present the designation start-up and subsequent key factors. Subsequent practical part is converted, through analysis and comparison, theoretical background in practice. This section presents the start-ups Crowdholding and Emuj and subsequently evaluated their key success factors. In another part I implements assessment of the factors of their success in terms of key aspects of the Blue Ocean strategy. Outputs are recommendations for potential investors in terms of controversy over business plans. The conclusion summarizes the theoretical and practical part of the thesis.
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chia-yi, Cheng, and 鄭佳宜. "Blue Star-Indigo Dyeing Work." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/77394769105954535365.
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碩士國立臺南藝術大學
應用藝術研究所
96
I used to listen to my inner voice in the past; I often asked myself what is my heart’s desire? What do I need the most? And where is my direction? After having such a long work experience, I have confused value with my life concept and my inner self-esteem is down; I can hardly breathe and am no longer free. Fortunately everything changed after I met the “Indigo dyeing”. This ancient and magical technique helped me find my lost soul; my mind, floating in the air, can now be settled and I can concentrate more on my daily routines. The indigo color is vivid; like a human being, it also needs air, food and water (hydrogen, sugar/wine and alkali). The pretty indigo color can be made by taking good care of it. I have spent a lot of time learning how to be a qualified carer. Dye vats are set one by one and slowly my successful experience accumulated from failures. The process is an integrated behavior. It provides the indigo color with an excellent existent condition and meanwhile its multi-layer color and aroma can be appreciated. If the existent condition is bad, the indigo color will be ugly. Due to lack of knowledge, I have searched for related dyeing techniques and studying advanced technology. An automatic learning motivation has been cultivated as I gradually unveil its mystery. Indigo dyeing is a traditional dyeing technique. It can always be seen in our daily utensils. It has also been developed as artistic creations. I have seen thousands of blue starts several years ago in the Cingjing Veterans Farm and I would love to convey my admiration to everyone. The indigo dyeing gives me an exit. It represents the beauty of stars and integrates with the starlight. The dialogue between a profound touching from my heart and my favorite traditional technique has been started and the work of “Blue Stars” is the spirit of my creation.
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He, Ya-Wen, and 何雅雯. "The Poetics of Solitude：Self-Writing of the Blue-Star Poets." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/18141260466687894617.
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博士國立臺灣大學
中國文學研究所
98
This study that cited the analysis of “Solitude” from Philip Koch, and focused on the poems of the Blue-Star Poetry Society, tried to discuss the consciousness of solitude and self-writing. The sociality of the Blue-Star Poetry Society was not strong enough, so there were lots of members who participate in the activities of the poetry society, publicize or publish their poems individually. Therefore, this study adopted the broader recognition, poets who had ever participated the inauguration of the Poetry Society, who had received the credit of the Poetry society, or who had published their works by the poetry society were included in the sampling field. According to this, this study can focus on the discusses of poets and their poems without the banner of the claims and conceptions of the poetry society. This study were probe into self-writing in solitary. It could be separated into two parts: first,.to make the self-writing by lyric poetry; second, to make the self-metaphor by extrinsic object such as plants or animals and so on. To make the self-writing, the poets presented self-determination or thinking by the speaker to establish self-image; they sat or walked in solitude situations, and gazed self, opened dialogue. Among them, which there were relationships between not only speaker and the audience but authors and readers. To make the self-metaphor by extrinsic object, most plants and animals, other broad matters still were worth to be explored. Besides, solitude situations and other emotions often interact with each other. Loneliness is one of the most striking feelings. Therefore, this study made interpretations about “the face and posture of lonely young poets”, as an example to young poets in Blue-Star Poetry Society.
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"Amsonia kearneyana (Apocynaceae) Kearney’s Blue Star: New Insights to Inform Recovery." Master's thesis, 2015. http://hdl.handle.net/2286/R.I.36041.
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abstract: Amsonia kearneyana is an endangered herbaceous plant endemic to a small area of the Baboquivari Mountains in southern Arizona. It exists in two distinct habitat types: 1) along the banks of a lower elevation ephemeral stream in a xeroriparian community, and 2) a higher elevation Madrean oak woodland on steep mountain slopes. Half of the largest known montane population (Upper Brown Canyon) was burned in a large fire in 2009 raising questions of the species capacity to recover after fire. This research sought to understand how the effects of fire will impact A. kearneyana's ability to recruit and survive in the burned versus unburned areas and in the montane versus xeroriparian habitat.
I compared population size, abiotic habitat characteristics, leaf traits, plant size, and reproductive output for plants in each habitat area for three years. Plants in the more shaded unburned montane area, the most populated population, presented with the most clonal establishment but produced the least amount of seeds per plant. The unshaded burned area produced more seeds per plant than in the unburned area. Lower Brown Canyon, the xeroriparian area, had the fewest plants, but produced the most seeds per plant while experiencing higher soil temperature, soil moisture, photosynthetically active radiation, and canopy cover than the montane plants. This could indicate conditions in Lower Brown Canyon are more favorable for seed production.
Despite ample seed production, recruitment is rare in wild plants. This study establishes germination requirements testing soil type, seed burial depth, temperature regimes, and shade treatments. Trials indicate that A. kearneyana can germinate and grow in varied light levels, and that soil type and seed burial depth are better predictors of growth than the degree of shade.
Finally, this study examined the law, regulation, policy, and physiological risks and benefits of a new management strategy and suggests that "conservation by dissemination" is appropriate for A. kearneyana. Conservation by dissemination is the idea that a protected plant species can be conserved by allowing and promoting the propagation and sale of plants in the commercial market with contingent collection of data on the fate of the sold individuals.Dissertation/Thesis
Masters Thesis Plant Biology 2015
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Chengwei, Liu, and 劉正偉. "A Study of the Early Period (1954-1971) of the Blue Star (Lan Xing) Poetry Society." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/58637183466069533740.
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博士佛光大學
文學系
100
This dissertation is a study of the early history of the Blue Star (Lan Xing) Poetry Society in Taiwan: its founding, its structure, its development and its achievement. There are a total of six Blue Star poetry periodicals in this early period (1954-1971) of the society. Samples of poems published in these periodicals are taken and analyzed. Subject matters, themes as well as authorial backgrounds of the samples are investigated; also examined are various poetic theories popular in the 1950s and 1960s as embodied in those poems. During the 1950s, authors of modern Chinese poetry explored different possibilities in their writing. There were several heated debates on the writing of poetry; for instance, the issue of poetic Westernization versus adherence to traditional Chinese ways of versification. Blue Star Poetry Society members, through experiments and experiences, achieved a poetics of blending the traditional and the modern, the Chinese and the Western; they produced works worthy of their hard efforts. Moreover, they translated modern Western poetry into Chinese and they taught the younger generation to write modern poetry. All these added, members of the Blue Star Poetry Society have contributed very significantly to the development of modern Chinese literature in Taiwan.
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Weidmann, Walter Alfredo. "Características físicas comparativas de nebulosas planetarias con estrellas centrales ricas y pobres en hidrógeno /." Doctoral thesis, 2009. http://hdl.handle.net/11086/125.
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Tesis (Doctor en Astronomia)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física, 2009.Con el objeto de aumentar el número de estrellas centrales de nebulosas planetarias con tipo espectral determinado, y buscar posibles diferencias estadísticas que nos permitan caracterizar los núcleos ricos de los pobres en hidrógeno, es que iniciamos un estudio observacional de estos objetos. Para esto estudiamos una muestra homogénea propia de más de setenta NP. Los resultados mas importantes que se consiguieron son los siguientes: Incrementamos un 19% el número conocido de estos objetos. Y observamos que las estrellas deficientes en hidrógeno poseen nebulosas de mayor densidad, mayor excitación, mayor abundancia de oxígeno y son de tamaño angular relativamente pequeño. Estos resultados son razonablemente consistentes con el modelo de “born-again” para explicar la ausencia de hidrógeno en estas estrellas.
Walter Alfredo Weidmann.
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Giesers, Benjamin David. "Spectroscopy of Binaries in Globular Clusters." Doctoral thesis, 2019. http://hdl.handle.net/21.11130/00-1735-0000-0005-13B4-A.
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Tillich, Franz Alfred [Verfasser]. "Hyper-velocity stars : a spectroscopic and kinematic study of blue stars / vorgelegt von Franz Alfred Tillich." 2010. http://d-nb.info/100301805X/34.
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CHOU, YU-PING, and 周玉萍. "How does an ESG-Oriented Social Enterprise Start-Up Make Profit? A Case Study of Taiwan Blue Magpie Tea." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/fcc9hw.
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碩士國立臺灣科技大學
財務金融研究所
107
Based on case study research method, this study discusses how an ESG-oriented social enterprise start-up has been trying to get balance between ecosystem and economy. With the entrepreneurship, Mr. Huang Po-Chun founded the company of BlueMagpie Tea Social Enterprise Co. Ltd. As a social enterprise when he pursuing his doctoral degree at the Graduate Institute of Building and Planning, National Taiwan University after serving for the Society of Wildness and the Chinese Wild Bird Federation respectively. Based on the spirit of Satoyama Initiative, Mr.Huang began with the two proposals of Distributors Yielding Profits and Tea Farmers Yielding the Land, and Recovering the Drainage Basin, hoping to clarify and confirm the business model of the brand in order to reach the balance of ecosystem and economic livelihoods. Then, he and his team utilized the mechanism of ambidexterity to expand their action plans. On the one hand, his team has been continually serving for the tutoring for the children of tea farmers, then wining trust from farmers in order to convince them to change their way of farming as well as involving famers in the pricing model to raise the purchase price. On the other hand, all the tea products have been undergoing full inspection for pesticide residues to gain consumer confidence. In addition, the company invited tea farmers to run the business cooperatively, guiding farmers to create value through branding. Further, Mr. Huang and his team also implemented many activities which were different from the past to help farmers’ living, such as the educational program in the farmland, volunteering activities, and one-day tour in the tea mountains. They also held workshops for the tea farmers and their offspring, winning back their recognition to the home business and reconstructing the cultural landscape in the villages. The team has been cooperating with companies that highlighted social responsibilities on corporate contracts of the tea farms and working holiday for their employees etc. To reach the goal of eco-village and based on the strategy of Recovering the Drainage Basin, Mr. Huang has been proactively assisting to expand the commercial channels for these farmers who adopt environmentally friendly farming to sell their products. The combination of farming and education model can also be utilized in other areas that have the conflicts between ecosystem and economic development. Mr.Huang has been acting as a pioneer to assist farmers for creating and enhancing the values of Pin Lin areas, with the expectations to reach the balance of environmental sustainability and economic development. This case is an ongoing development case. The discussions can be considered as a reference for other social enterprises that involve environmental sustainability. It would be of valuable references to those have to compromise between ecosystem and economic development.
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Wang, Chao-Kuei, and 王朝葵. "Effect of Glucose Stat and pH Stat Control Strategies on Fed-Batch Fermentation of Recombinant E. coli XL1 Blue for the production of a Fusion Protein of Sweet Potato Sporamin." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/85845410239562680872.
Full textAbstract:
碩士大同工學院
生物工程研究所
87
ABSTRACT Sporamin is the major storage protein in sweet potato tuberous roots. It has been found to have trypsin inhibitor activity. The sporamin in the sweet potato root performs not only the nutrient for the growth of sweet potato but also a direct defensive role of sweet potato against insects infestations. In the present study, a recombinant E. coli, whch harbors inducible pGEX-2T plasmid vector inserted sporamin cDNA from Ipomoea batatas (L.)Lam. cv Tainong 57 sweet potato, was used to express GST-sporamin fusion protein. The fermentation is at 37℃and 500 rpm in aeration condition. In batch fermentation, 0.1 mM IPTG was employed to induce production of GST-sporamin fusion protein. The optimum induction time was 10 hrs. The yield of GST-sporamin fusion protein was 10 % among the crude extract from the cells. In the glucose stat fed-batch fermentation, glucose concentration was controlled at 1 g/l. The cell density of OD600 at 55.5 could be obtained after 30 hrs, and yield of GST-sporamin was 8.9 %. In the pH stat fed-batch fermentation, pH was controlled between 6.5~6.55 and glucose was supplied as carbon source. The cell density of OD600 at 34 could be obtained after 40 hrs, and yield of GST-sporamin was 6.8 %. If glycerol was used instead of glucose as carbon source in the pH stat fermentation, the cell density of OD600 at 59 could be obtained after 50 hrs, and yield of GST-sporamin was 12.3 %. To keep sufficient ampicillin during fermentation was very important to achieve a high yield of GST-sporamin. The yield of GST-sporamin could be less than 1 % in the crude extract of cells for insufficient ampicillin was in the cultural broth during fermentation.