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Articles de revues sur le sujet « Astrophysics Technique »

Auteur : Grafiati

Publié le 4 juin 2021

Mis à jour le 31 janvier 2023

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1

Shen, Yang-Ping, Bing Guo, and Wei-Ping Liu. "An indirect technique in nuclear astrophysics: alpha-cluster transfer reaction." EPJ Web of Conferences 260 (2022): 01001. http://dx.doi.org/10.1051/epjconf/202226001001.

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Helium(4He, or α)is the second most abundant element in the observable Universe. The α-particle induced reactions such as(α, γ), (α, n) and (α, p) play a crucial role in nuclear astrophysics, especially for understanding stellar heliumburning. Because of the strong Coulomb repulsion, it is greatly hindered to directly measure the cross sections for these α-capture reactions at stellar energies. Alpha-cluster transfer reaction is a powerful tool for investigation of astrophysical(α, γ), (α, n)and(α, p)reactions since it can preferentially populate the natural-parity states with an α-cluster str

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Rahma, Siti Nur, Suliyanah Suliyanah, and Abdul Halim. "How do Astrophysics and the Qur'an Perceive the Extraterrestrial Life? A Qualitative Study." Jurnal Pendidikan Fisika 10, no. 2 (April 20, 2022): 107–22. http://dx.doi.org/10.26618/jpf.v10i2.7433.

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The topic of extraterrestrial life is still only a theory and the truth is still being investigated. Therefore, this research aims to analyze the beginning formation of the universe according to astrophysics and the Qur’an, astrophysics discoveries about extraterrestrial life, and letters in the Qur’an that hint at extraterrestrial life, as well as analyzing the relationship between astrophysics and letters in the Qur’an related to extraterrestrial life. This research is qualitative research with a method consisting of library research and interviews. The primary data of this research comes fr

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Longair, Malcolm. "Radio astronomy and the rise of high-energy astrophysics two anniversaries." International Journal of Modern Physics D 28, no. 02 (January 2019): 1930004. http://dx.doi.org/10.1142/s0218271819300040.

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This paper celebrates the 100th anniversary of the birth of Martin Ryle and the 50th anniversary of the discovery of pulsars by Jocelyn Bell and Antony Hewish. Ryle and Hewish received the 1974 Nobel Prize in Physics, the first in the area of astrophysics. Their interests strongly overlapped, one of the key papers on the practical implementation of the technique of aperture synthesis being co-authored by Ryle and Hewish. The discovery of pulsars and the roles played by Hewish and Bell are described. These key advances were at the heart of the dramatic rise of high-energy astrophysics in the 19

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Mukhamedzhanov, A. M., L. D. Blokhintsev, B. F. Irgaziev, A. S. Kadyrov, M. La Cognata, C. Spitaleri, and R. E. Tribble. "Trojan Horse as an indirect technique in nuclear astrophysics." Journal of Physics G: Nuclear and Particle Physics 35, no. 1 (December 13, 2007): 014016. http://dx.doi.org/10.1088/0954-3899/35/1/014016.

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Spitaleri, Claudio. "Trojan Horse technique to measure nuclear astrophysics rearrangement reactions." Journal of Physics: Conference Series 420 (March 25, 2013): 012137. http://dx.doi.org/10.1088/1742-6596/420/1/012137.

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Tumino, A., C. Spitaleri, S. Cherubini, V. Crucillà, C. Fu, Z. Elekes, Z. Fülöp, et al. "The trojan horse method as indirect technique in nuclear astrophysics." Journal of Physics: Conference Series 111 (May 1, 2008): 012033. http://dx.doi.org/10.1088/1742-6596/111/1/012033.

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Minier, Vincent, Gilles Durand, Pierre-Olivier Lagage, and M. Talvard. "CAMISTIC: THz/submm astronomy at Dome C in Antarctica." Proceedings of the International Astronomical Union 2, no. 14 (August 2006): 709–10. http://dx.doi.org/10.1017/s1743921307012367.

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Submillimetre (submm) astronomy is the prime technique to unveil the birth and early evolution of a broad range of astrophysical objects. It is a relatively new branch of observational astrophysics which focuses on studies of the cold Universe, i.e., objects radiating a significant – if not dominant – fraction of their energy at wavelengths ranging from ∼ 100 μm to ∼ 1 mm. Submm continuum observations are particularly powerful to measure the luminosities, temperatures and masses of cold dust emitting objects. Examples of such objects include star-forming clouds in our Galaxy, prestellar cores

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Bukvić, S., Dj Spasojević, and V. Žigman. "Advanced fit technique for astrophysical spectra." Astronomy & Astrophysics 477, no. 3 (November 12, 2007): 967–77. http://dx.doi.org/10.1051/0004-6361:20065969.

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Crossland, Tom, Pontus Stenetorp, Sebastian Riedel, Daisuke Kawata, Thomas D. Kitching, and Rupert A. C. Croft. "Towards machine-assisted meta-studies: the Hubble constant." Monthly Notices of the Royal Astronomical Society 492, no. 3 (December 23, 2019): 3217–28. http://dx.doi.org/10.1093/mnras/stz3400.

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ABSTRACT We present an approach for automatic extraction of measured values from the astrophysical literature, using the Hubble constant for our pilot study. Our rules-based model – a classical technique in natural language processing – has successfully extracted 298 measurements of the Hubble constant, with uncertainties, from the 208 541 available arXiv astrophysics papers. We have also created an artificial neural network classifier to identify papers in arXiv which report novel measurements. From the analysis of our results we find that reporting measurements with uncertainties and the cor

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SINNIS, GUS. "TeV ASTROPHYSICS WITH THE MILAGRO AND HAWC OBSERVATORIES." International Journal of Modern Physics D 22, no. 11 (September 2013): 1360010. http://dx.doi.org/10.1142/s0218271813600109.

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Ground-based gamma-ray astronomy has historically implemented two dramatically different techniques. One method employs Imaging Atmospheric Cherenkov Telescope(s) (IACT) that detect the Cherenkov light generated in the atmosphere by extensive air showers. The other method employs particle detectors that directly detect the particles that reach ground level — known as Extensive Air Shower (EAS) arrays. Until recently, the IACT method had been the only technique to yield solid detections of TeV gamma-ray sources. Utilizing water Chernkov technology, Milagro, was the first EAS array to discover n

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de la Fuente, Eduardo, Juan Carlos Díaz–Vélez, Paolo Desiati, Jose Luis García–Luna, Janet Torrealba, and Ricardo Gúzman–Alcála. "Information Technologies on High-Energy Astrophysics: Cosmic Ray Anisotropy using HAWC Observatory." EPJ Web of Conferences 208 (2019): 03005. http://dx.doi.org/10.1051/epjconf/201920803005.

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The detection of astroparticles, specially at high energies (>100 GeV), requires special techniques and instruments (telescopes or observatories), for example, those that use the Water Cherenkov radiation technique. In this paper we show an example of how Information Technologies can be used to perform maps and produce high impact results. The latter case is illustrated in the summary of the generation of a high statistics map of cosmic rays at 10 TeV in the northern sky with data collected by the High Altitude Water Cherenkov (HAWC) observatory.

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Devorkin, David H. "Takamine and Saha: Contacts with Western Astrophysics." Highlights of Astronomy 11, no. 2 (1998): 732–33. http://dx.doi.org/10.1017/s1539299600018621.

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In the fall of 1920 two young scholars happened to meet in London and found they had many interests in common in laboratory spectroscopy and astrophysics. One was an Indian and the other a Japanese, and their paths crossed as they visited American and European centers to learn the tools and techniques of the quantum theory. The young Japanese scholar, T. Takamine, whose home base was then the Institute of Physical and Chemical Research in Tokyo, was delighted to have met Meghnad Saha, from Calcutta, who was just putting the finishing touches on his fourth paper on ionization equilibrium in the

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Okuda, Haruyuki, Gunther Hasinger, M. D. Arnaud, S. Bludman, J. Braga, N. Brosch, L. Gurvits, et al. "Commission 44: Space & High Energy Astrophysics." Proceedings of the International Astronomical Union 1, T26A (December 2005): 319–26. http://dx.doi.org/10.1017/s1743921306004777.

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Division XI was born by merging Commission 44 “Space and High Energy Astrophysics” and Commission 48 “High Energy Astrophysics” by the decision at the IAU General Assembly in The Hague (1994). As the naming of space astronomy is technique oriented, i.e. astronomy from space, it covers quite a wide range of astronomy, almost all branches of astronomy are included by the progress of space observations. Historically, it started from high energy astronomy, UV, X, and gamma rays astronomy, somewhat including cosmic ray physics. However, in these days, space observations have expanded to low energy

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Meyers, Patrick M., Tanner Prestegard, Vuk Mandic, Victor C. Tsai, Daniel C. Bowden, Andrew Matas, Gary Pavlis, and Ross Caton. "A Linear Inversion Approach to Measuring the Composition and Directionality of the Seismic Noise Field." Remote Sensing 13, no. 16 (August 5, 2021): 3097. http://dx.doi.org/10.3390/rs13163097.

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We develop a linear inversion technique for measuring the modal composition and directionality of ambient seismic noise. The technique draws from similar techniques used in astrophysics and gravitational-wave physics, and relies on measuring cross-correlations between different seismometer channels in a seismometer array. We characterize the sensitivity and the angular resolution of this technique using a series of simulations and real-world tests. We then apply the technique to data acquired by the three-dimensional seismometer array at the Homestake mine in Lead, SD, to estimate the composit

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Dhiman, Gaurav, and Vijay Kumar. "Astrophysics inspired multi-objective approach for automatic clustering and feature selection in real-life environment." Modern Physics Letters B 32, no. 31 (November 10, 2018): 1850385. http://dx.doi.org/10.1142/s0217984918503852.

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In this paper, a novel astrophysics-based approach is proposed for automatically finding the clusters and features simultaneously. A novel agent encoding scheme is used to encode both the number of clusters and features. A novel dynamic threshold technique is proposed for an efficient searching. The validation of proposed technique is tested on eight real-life data sets. The statistical significance of proposed technique is attributed by statistical tests. It is also applied on solving image segmentation and microarray data analysis problems. Experimental results reveal that the proposed techn

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Deniz, Sinan, and Necdet Bildik. "A new analytical technique for solving Lane - Emden type equations arising in astrophysics." Bulletin of the Belgian Mathematical Society - Simon Stevin 24, no. 2 (April 2017): 305–20. http://dx.doi.org/10.36045/bbms/1503453712.

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Bigg, Charlotte. "Travelling Scientist, Circulating Images and the Making of the Modern Scientific Journal." Nuncius 30, no. 3 (2015): 675–98. http://dx.doi.org/10.1163/18253911-03003002.

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The early astrophysicist Norman Lockyer was both editor of the journal Nature from its creation in 1869 and for the following five decades, and an early practioner of the new astronomy. He frequently used the journal to expound his scientific theories, report on his work and send news home while on expeditions. I look into the particular visual culture of astrophysics developed by Lockyer in Nature, its evolution at a time of rapid development both of the techniques of astrophysical observation and visualization and of the techniques of image reproduction in print. A study of the use and reuse

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Ma, Wen-Xiu, Mohamed M. Mousa, and Mohamed R. Ali. "Application of a new hybrid method for solving singular fractional Lane–Emden-type equations in astrophysics." Modern Physics Letters B 34, no. 03 (December 19, 2019): 2050049. http://dx.doi.org/10.1142/s0217984920500499.

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In this research, a hybrid numerical method combining cosine and sine (CAS) wavelets and Green’s function approach is created to acquire the arrangements of fractional Lane–Emden Problem. The suggested methodology for detecting the solution of nonlinear equations dependent on variations of germinal algorithms is applied on nonlinear fractional Lane–Emden Problem under some smooth conditions and results in an iterative scheme of nonlinear equations Because of its efficiency, this technique is applied on a large variety of equations from the boundary value problems to the optimization. This pape

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Barrett, Jim W., Ilya Mandel, Coenraad J. Neijssel, Simon Stevenson, and Alejandro Vigna-Gómez. "Exploring the Parameter Space of Compact Binary Population Synthesis." Proceedings of the International Astronomical Union 12, S325 (October 2016): 46–50. http://dx.doi.org/10.1017/s1743921317000059.

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AbstractAs we enter the era of gravitational wave astronomy, we are beginning to collect observations which will enable us to explore aspects of astrophysics of massive stellar binaries which were previously beyond reach. In this paper we describe COMPAS (Compact Object Mergers: Population Astrophysics and Statistics), a new platform to allow us to deepen our understanding of isolated binary evolution and the formation of gravitational-wave sources. We describe the computational challenges associated with their exploration, and present preliminary results on overcoming them using Gaussian proc

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MOTOBAYASHI, TOHRU. "NUCLEAR STRUCTURE AND NUCLEAR ASTROPHYSICS STUDIES WITH FAST HEAVY-ION BEAMS." International Journal of Modern Physics E 18, no. 10 (November 2009): 1965–69. http://dx.doi.org/10.1142/s0218301309014093.

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Collaboration between France and Japan on studies with fast RI (radioactive isotope) beams and related technical developments started in 1980s, when the GANIL accelerators and RIKEN cyclotron complex started operation and RI beam production technique was developed. Several examples of collaboration on nuclear physics and nuclear astrophysics experiments including related technical development are discussed.

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Rastorguev, Alexey S., Andrey K. Dambis, Marina V. Zabolotskikh, Leonid N. Berdnikov, and Natalia A. Gorynya. "The Baade–Becker–Wesselink technique and the fundamental astrophysical parameters of Cepheids." Proceedings of the International Astronomical Union 8, S289 (August 2012): 195–202. http://dx.doi.org/10.1017/s1743921312021382.

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AbstractThe Baade–Becker–Wesselink (BBW) method remains one of most often used tools to derive a full set of Cepheid astrophysical parameters. The surface brightness version of the BBW technique was preferentially used during the past few decades to calculate Cepheid radii and to improve period–luminosity–colour relations. Its implementation requires a priori knowledge of Cepheid reddening values. We propose a new version of the BBW technique, which allows one to independently determine the colour excess and the intrinsic colour of a radially pulsating star, in addition to its radius, luminosi

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Wang, Ru-Yue, Jian-Fu Zhang, Alex Lazarian, Hua-Ping Xiao, and Fu-Yuan Xiang. "Gradient measurement of synchrotron polarization diagnostic: Application to spatially separated emission and Faraday rotation regions." Monthly Notices of the Royal Astronomical Society 505, no. 4 (June 17, 2021): 6206–16. http://dx.doi.org/10.1093/mnras/stab1708.

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ABSTRACT Considering the spatially separated polarization radiation and Faraday rotation regions to simulate complex interstellar media, we study synchrotron polarization gradient techniques’ measurement capabilities. We explore how to trace the direction of projected magnetic field of emitting-source region at the multifrequency bands, using the gradient technique compared with the traditional polarization vector method. Furthermore, we study how Faraday rotation density in the foreground region, i.e. a product of electron number density and parallel component of magnetic fields along the lin

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Eesa, Bushra. "Modified Hermite Operational Matrix Method for Nonlinear Lane-Emden Problem." Al-Qadisiyah Journal Of Pure Science 25, no. 3 (June 27, 2020): 71–79. http://dx.doi.org/10.29350/qjps.2020.25.3.1128.

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Nonlinear Lane –Emden equations are significant in astrophysics and mathematical physics. The aim of this paper is submitted a new approximate method for finding solution to nonlinear Lane-Emden type equations appearing in astrophysics based on modified Hermite integration operational matrix. The suggest technique is based on taking the truncated modified Hermite series of the solution function in the nonlinear Lane-Emden equation and then changed into a matrix equation with the given conditions. Nonlinear system of algebraic equation using collection points is obtained. The present method is

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Mirzoyan, Razmik. "Technological Novelties of Ground-Based Very High Energy Gamma-Ray Astrophysics with the Imaging Atmospheric Cherenkov Telescopes." Universe 8, no. 4 (March 29, 2022): 219. http://dx.doi.org/10.3390/universe8040219.

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In the past three decades, the ground-based technique of imaging atmospheric Cherenkov telescopes has established itself as a powerful discipline in science. Approximately 250 sources of very high gamma rays of both galactic and extra-galactic origin have been discovered largely due to this technique. The study of these sources is providing clues to many basic questions in astrophysics, astro-particle physics, physics of cosmic rays and cosmology. The currently operational generation of telescopes offer a solid performance. Further improvements of this technique led to the next-generation larg

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GRUN, J., M. LAMING, C. MANKA, D. W. DONNELLY, B. C. COVINGTON, R. P. FISCHER, A. VELIKOVICH, and A. KHOKHLOV. "Laser–plasma simulations of astrophysical phenomena and novel applications to semiconductor annealing." Laser and Particle Beams 21, no. 4 (October 2003): 529–34. http://dx.doi.org/10.1017/s0263034603214087.

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At the frontier of plasma physics and technology are applications of laser-generated plasmas to laboratory simulations of astrophysical phenomena and to industrial processing. This article presents work at the Naval Research Laboratory in both of these areas. We show how laser plasmas are used to measure a blast wave corrugation overstability important in astrophysics. Detailed atomic physics calculations of radiative cooling within the blast front are used to develop a criterion of the existence of the overstability and are used to explain the experimental results. The criterion depends on qu

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Heald, George. "The Faraday rotation measure synthesis technique." Proceedings of the International Astronomical Union 4, S259 (November 2008): 591–602. http://dx.doi.org/10.1017/s1743921309031421.

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AbstractWe discuss practical aspects of the novel Faraday Rotation Measure Synthesis technique, first described by Burn (1966), and recently extended and implemented by Brentjens & de Bruyn (2005). The method takes advantage of the excellent spectral coverage provided by modern radio telescopes to reconstruct the intrinsic polarization properties along a line of sight, using a Fourier relationship between the observed polarization products and a function describing the intrinsic polarization (the Faraday dispersion function). An important consequence of the Fourier relationship and discret

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Shannon, Ryan. "Constraining the nanohertz gravitational wave background with the Parkes Pulsar Timing Array." Proceedings of the International Astronomical Union 8, S291 (August 2012): 177. http://dx.doi.org/10.1017/s174392131202354x.

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AbstractThe direct detection of gravitational waves will usher in a new era of astrophysics, enabling the study of regions of the universe opaque to electromagnetic radiation or electromagnetically quiet. An ensemble of pulsars (referred to as a pulsar timing array) provides a set of clocks distributed across the Galaxy sensitive to gravitational waves with periods on the order of five years (frequencies of many nanohertz). Plausible source of gravitational waves in this frequency band include massive black hole binaries in the throes of mergers and oscillating cosmic strings. The stochastic g

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Alves, João, Marco Lombardi, and Charles Lada. "Insights on molecular cloud structure." Proceedings of the International Astronomical Union 6, S270 (May 2010): 99–102. http://dx.doi.org/10.1017/s1743921311000238.

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AbstractStars form in the densest regions of clouds of cold molecular hydrogen. Measuring structure in these clouds is far from trivial as 99% of the mass of a molecular cloud is inaccessible to direct observation. Over the last decade we have been developing an alternative, more robust density tracer technique based on dust extinction measurements towards background starlight. The new technique does not suffer from the complications plaguing the more conventional molecular line and dust emission techniques, and when used with these can provide unique views on cloud chemistry and dust grain pr

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Casali, G., L. Magrini, A. Frasca, A. Bragaglia, G. Catanzaro, V. D’Orazi, R. Sordo, et al. "Stellar Population Astrophysics (SPA) with TNG." Astronomy & Astrophysics 643 (October 27, 2020): A12. http://dx.doi.org/10.1051/0004-6361/202039176.

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Context. Open clusters are excellent tracers of the chemical evolution of the Galactic disc. The spatial distribution of their elemental abundances, through the analysis of high-quality and high-resolution spectra, provides insight into the chemical evolution and mechanisms of element nucleosynthesis in regions characterised by different conditions (e.g. star formation efficiency and metallicity). Aims. In the framework of the Stellar Population Astrophysics (SPA) project, we present new observations and spectral analysis of four sparsely studied open clusters located in the solar neighbourhoo

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Landolt, Arlo U., Peter Martinez, Pierre Bastien, Sergei N. Fabrika, Ronald L. Gilliland, Frank Grundahl, Carme Jordi, and Ulisse Munari. "COMMISSION 25: STELLAR PHOTOMETRY AND POLARIMETRY." Proceedings of the International Astronomical Union 3, T26B (December 2007): 192–94. http://dx.doi.org/10.1017/s1743921308024071.

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Mantovani Sarti, Valentina. "Hyperon-nucleon femtoscopy, nuclear production and bearing on astrophysics." EPJ Web of Conferences 259 (2022): 05003. http://dx.doi.org/10.1051/epjconf/202225905003.

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The presence of hyperons in the inner core of neutron stars is still an open issue in astrophysics and the so-called hyperon puzzle is far away from being solved. A complete understanding of how the interaction between hyperons and nucleons, at the level of two- and three-body, behaves in vacuum and at finite baryon density is a key requirement in order to build a realistic Equation of State for matter inside the core of neutron stars. Recently, measurements of hadron-hadron correlation functions with the femtoscopy technique in small colliding systems delivered a large amount of precise data

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Li, T. P. "Imaging in Hard X-ray Astronomy." Symposium - International Astronomical Union 214 (2003): 70–83. http://dx.doi.org/10.1017/s0074180900194173.

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The energy range of hard X-rays is a key waveband to the study of high energy processes in celestial objects, but still remains poorly explored. In contrast to direct imaging methods used in the low energy X-ray and high energy gamma-ray bands, currently imaging in the hard X-ray band is mainly achieved through various modulation techniques. A new inversion technique, the direct demodulation method, has been developed since early 90s. with this technique, wide field and high resolution images can be derived from scanning data of a simple collimated detector. The feasibility of this technique h

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Kashem, Bushra Esaa, and Suha SHIHAB. "Approximate solution of Lane-Emden problem via modified Hermite operation matrix method." Samarra Journal of Pure and Applied Science 2, no. 2 (September 22, 2021): 57–67. http://dx.doi.org/10.54153/sjpas.2020.v2i2.113.

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    Lane-Emden equations are singular initial value problems and they are important in mathematical physics and astrophysics. The aim of this present paper is presenting a new numerical method for finding approximate solution to Lane-Emden type equations arising in astrophysics based on modified Hermite operational matrix of integration. The proposed technique is based on taking the truncated modified Hermite series of the solution function in the Lane-Emden equation and then transferred into a matrix equation together with the given conditions. The obtained result is s

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Valbusa Dall'Armi, Lorenzo, Angelo Ricciardone, and Daniele Bertacca. "The dipole of the astrophysical gravitational-wave background." Journal of Cosmology and Astroparticle Physics 2022, no. 11 (November 1, 2022): 040. http://dx.doi.org/10.1088/1475-7516/2022/11/040.

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Abstract One of the main pillars of the ΛCDM model is the Cosmological Principle, which states that our Universe is statistically isotropic and homogeneous on large scales. Here we test this hypothesis using the Astrophysical Gravitational Wave Background (AGWB) expected to be measured by the Einstein Telescope-Cosmic Explorer network; in particular we perform a numerical computation of the AGWB dipole, evaluating the intrinsic contribution due to clustering and the kinematic effect induced by the observer motion. We apply a component separation technique in the GW context to disentangle the k

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Trudu, Matteo, Maura Pilia, Gregory Hellbourg, Pierpaolo Pari, Nicolò Antonietti, Claudio Maccone, Andrea Melis, Delphine Perrodin, and Alessio Trois. "Performance analysis of the Karhunen–Loève Transform for artificial and astrophysical transmissions: denoizing and detection." Monthly Notices of the Royal Astronomical Society 494, no. 1 (March 13, 2020): 69–83. http://dx.doi.org/10.1093/mnras/staa694.

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ABSTRACT In this work, we propose a new method of computing the Karhunen–Loève Transform (KLT) applied to complex voltage data for the detection and noise level reduction in astronomical signals. We compared this method with the standard KLT techniques based on the Toeplitz correlation matrix and we conducted a performance analysis for the detection and extraction of astrophysical and artificial signals via Monte Carlo (MC) simulations. We applied our novel method to a real data study-case: the Voyager 1 telemetry signal. We evaluated the KLT performance in an astrophysical context: our techni

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Khozov, G. V. "Photometric technique for selecting cool carbon stars." Astrophysics 35, no. 2-3 (1992): 378–80. http://dx.doi.org/10.1007/bf01003991.

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Chen, Zhaoting, Laura Wolz, Marta Spinelli, and Steven G. Murray. "Extracting H i astrophysics from interferometric intensity mapping." Monthly Notices of the Royal Astronomical Society 502, no. 4 (February 11, 2021): 5259–76. http://dx.doi.org/10.1093/mnras/stab386.

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ABSTRACT We present a new halo model of neutral hydrogen (H i) calibrated to galaxy formation simulations at redshifts z ∼ 0.1 and z ∼ 1.0 that we employ to investigate the constraining power of interferometric H i intensity mapping on H i astrophysics. We demonstrate that constraints on the small-scale H i power spectrum can break the degeneracy between the H i density $\Omega _{\rm H\, \small {I}}$ and the H i bias $b_{\rm H\, \small {I}}$. For z ∼ 0.1, we forecast that an accurate measurement of $\Omega _{\rm H\, \small {I}}$ up to 6 per cent level precision and the large-scale H i bias $b_

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Heydari, Mohammad, Ghasem Barid Loghmani, and Abdul-Majid Wazwaz. "A numerical approach for a class of astrophysics equations using piecewise spectral-variational iteration method." International Journal of Numerical Methods for Heat & Fluid Flow 27, no. 2 (February 6, 2017): 358–78. http://dx.doi.org/10.1108/hff-09-2015-0379.

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Purpose The main purpose of this paper is to implement the piecewise spectral-variational iteration method (PSVIM) to solve the nonlinear Lane-Emden equations arising in mathematical physics and astrophysics. Design/methodology/approach This method is based on a combination of Chebyshev interpolation and standard variational iteration method (VIM) and matching it to a sequence of subintervals. Unlike the spectral method and the VIM, the proposed PSVIM does not require the solution of any linear or nonlinear system of equations and analytical integration. Findings Some well-known classes of Lan

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Benhar, Omar, Alessandro Lovato, and Giovanni Camelio. "Modeling Neutron Star Matter in the Age of Multimessenger Astrophysics." Astrophysical Journal 939, no. 1 (November 1, 2022): 52. http://dx.doi.org/10.3847/1538-4357/ac8e61.

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Abstract The interpretation of available and forthcoming data obtained from multimessenger astrophysical observations—potentially providing unprecedented access to neutron star properties—will require the development of novel, accurate theoretical models of dense matter. Of great importance, in this context, will be the capability for devising a description of thermal effects applicable to the study of quantities other than the equation of state, such as the transport coefficients and the neutrino mean free path in the nuclear medium. A formalism based on correlated basis states and the cluste

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Aielli, G., C. Bacci, F. Barone, B. Bartoli, P. Bernardini, X. J. Bi, C. Bleve, et al. "Scaler mode technique for the ARGO-YBJ detector." Astroparticle Physics 30, no. 2 (September 2008): 85–95. http://dx.doi.org/10.1016/j.astropartphys.2008.07.002.

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Miller, Jonathan, and Roman Pasechnik. "Quasi-Classical Gravity Effect on Neutrino Oscillations in a Gravitational Field of a Heavy Astrophysical Object." Advances in High Energy Physics 2015 (2015): 1–15. http://dx.doi.org/10.1155/2015/381569.

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In the framework of quantum field theory, a graviton interacts locally with a quantum state having definite mass, that is, the gravitational mass eigenstate, while a weak boson interacts with a state having definite flavor, that is, the flavor eigenstate. An interaction of a neutrino with an energetic graviton may trigger the collapse of the neutrino to a definite mass eigenstate with probability expressed in terms of PMNS mixing matrix elements. Thus, gravitons would induce quantum decoherence of a coherent neutrino flavor state similarly to how weak bosons induce quantum decoherence of a neu

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Gucsik, Arnold, Hirotsugu Nishido, Kiyotaka Ninagawa, Ulrich Ott, Akira Tsuchiyama, Masahiro Kayama, Irakli Simonia, and Jean-Paul Boudou. "Cathodoluminescence Microscopy and Spectroscopy of Micro- and Nanodiamonds: An Implication for Laboratory Astrophysics." Microscopy and Microanalysis 18, no. 6 (December 2012): 1285–91. http://dx.doi.org/10.1017/s143192761201330x.

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AbstractColor centers in selected micro- and nanodiamond samples were investigated by cathodoluminescence (CL) microscopy and spectroscopy at 298 K [room temperature (RT)] and 77 K [liquid-nitrogen temperature (LNT)] to assess the value of the technique for astrophysics. Nanodiamonds from meteorites were compared with synthetic diamonds made with different processes involving distinct synthesis mechanisms (chemical vapor deposition, static high pressure high temperature, detonation). A CL emission peak centered at around 540 nm at 77 K was observed in almost all of the selected diamond samples

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Dwyer, Sheila E., Georgia L. Mansell, and Lee McCuller. "Squeezing in Gravitational Wave Detectors." Galaxies 10, no. 2 (March 9, 2022): 46. http://dx.doi.org/10.3390/galaxies10020046.

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Injecting optical squeezed states of light, a technique known as squeezing, is now a tool for gravitational wave detection. Its ability to reduce quantum noise is helping to reveal more gravitational wave transients, expanding the catalog of observations in the last observing run. This review introduces squeezing and its history in the context of gravitational-wave detectors. It overviews the benefits, limitations and methods of incorporating squeezing into advanced interferometers, emphasizing the most relevant details for astrophysics instrumentation.

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Trinczek, M., S. Lapi, B. Guo, F. Ames, K. R. Buckley, J. M. D'Auria, K. Jayamanna, W. P. Liu, C. Ruiz, and T. J. Ruth. "Production of intense radioactive beams at ISAC using low-energy protons." Canadian Journal of Physics 84, no. 4 (April 1, 2006): 325–33. http://dx.doi.org/10.1139/p06-058.

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A proof-of-principle approach for the production of intense (~108/s) radioactive ion beams, which differs from the standard ISOL (Isotope Separation On-Line) technique, has been demonstrated successfully using 11C at the TRIUMF laboratory. This approach uses 13 MeV protons produced by a medical cyclotron and should be useful for a range of radioisotopes of interest to the nuclear astrophysics research programme.PACS No.: 29.25.Rm

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Sarkar, Subhajit, Nikku Madhusudhan, and Andreas Papageorgiou. "JexoSim: a time-domain simulator of exoplanet transit spectroscopy with JWST." Monthly Notices of the Royal Astronomical Society 491, no. 1 (October 22, 2019): 378–97. http://dx.doi.org/10.1093/mnras/stz2958.

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ABSTRACT The James Webb Space Telescope (JWST) will perform exoplanet transit spectroscopy in the coming decade, promising transformative science results. All four instruments onboard can be used for this technique that reconstructs the atmospheric transmission or emission spectrum of an exoplanet from wavelength-dependent light-curve measurements. Astrophysical and instrumental noise and systematics can affect the precision and accuracy of the final spectrum, and hence, the atmospheric properties derived from the spectrum. Correlated noise and time-dependent systematics that can bias the meas

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Gastis, P., G. Perdikakis, G. P. A. Berg, A. C. Dombos, A. Estrade, A. Falduto, M. Horoi, et al. "A technique for the study of (p,n) reactions with unstable isotopes at energies relevant to astrophysics." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 985 (January 2021): 164603. http://dx.doi.org/10.1016/j.nima.2020.164603.

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Jeffery, Elizabeth J. "Observational problems in determining the ages of open clusters." Proceedings of the International Astronomical Union 4, S258 (October 2008): 141–52. http://dx.doi.org/10.1017/s1743921309031792.

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AbstractOpen clusters have long been objects of interest in astronomy. As a good approximation of essentially pure stellar populations, they have proved very useful for studies in a wide range of astrophysically interesting questions, including stellar evolution and atmospheres, the chemical and dynamical evolution of our Galaxy, and the structure of our Galaxy. Of fundamental importance to our understanding of open clusters is accurate determinations of cluster ages. Currently there are two main techniques for independently determining the ages of stellar populations: main sequence evolution

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Wang, Shuang, Sixiang Wen, and Miao Li. "Exploring JLA supernova data with improved flux-averaging technique." Journal of Cosmology and Astroparticle Physics 2017, no. 03 (March 15, 2017): 037. http://dx.doi.org/10.1088/1475-7516/2017/03/037.

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Yan, Yihua, Baolin Tan, V. Melnikov, Xingyao Chen, Wei Wang, Linjie Chen, and Fei Liu. "Diagnosing coronal magnetic fields with radio imaging-spectroscopy technique." Proceedings of the International Astronomical Union 15, S354 (June 2019): 17–23. http://dx.doi.org/10.1017/s1743921320000629.

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AbstractMingantu Spectral Radioheliograph (MUSER) is an aperture-synthesis imaging telescope, dedicated to observe the Sun, operating on multiple frequencies in dm to cm range. The ability of MUSER to get images and measure Stokes I and V parameters simultaneously at many frequencies in a wide band is of fundamental importance. It allows one to approach/solve such important problems as measuring the strength, geometry and dynamics of magnetic field at coronal heights. Here we consider some of the recently developed radio physics methods to be used for solving the problems. These methods allow

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Janett, Gioele, Oskar Steiner, Ernest Alsina Ballester, Luca Belluzzi, and Siddhartha Mishra. "A novel fourth-order WENO interpolation technique." Astronomy & Astrophysics 624 (April 2019): A104. http://dx.doi.org/10.1051/0004-6361/201834761.

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Context. Several numerical problems require the interpolation of discrete data that present at the same time (i) complex smooth structures and (ii) various types of discontinuities. The radiative transfer in solar and stellar atmospheres is a typical example of such a problem. This calls for high-order well-behaved techniques that are able to interpolate both smooth and discontinuous data. Aims. This article expands on different nonlinear interpolation techniques capable of guaranteeing high-order accuracy and handling discontinuities in an accurate and non-oscillatory fashion. The final aim i

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