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Rr Lyrae Stars In The Milky Way Stellar Halo
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Book Synopsis RR Lyrae Stars in the Milky Way Stellar Halo by : Shaila Akhter
Download or read book RR Lyrae Stars in the Milky Way Stellar Halo written by Shaila Akhter and published by . This book was released on 2013 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: A current important research topic in modern Astrophysics is to understand the formation process of galaxies like the Milky Way. The Milky Way Stellar Halo preserves the most useful information about the Galaxy evolution. Despite a number of detailed studies over many years, the shape and extent of the Galactic Halo is still debated and knowledge about it is incomplete. The existence of the halo stellar streams provides important clues to the hierarchical formation of our galaxy. We study these substructures through the characteristics of various stellar populations. RR Lyraes (RRLs) are very good Galactic halo tracers because of their relatively high intrinsic and well established absolute magnitudes. RRLs are metal poor and very old and can hold information of galaxy evolution. Their characteristic colors and light curves made them easy to be identified. Keller et al. (2008) found that the power-law slope of the RR Lyrae space density distribution is steepened beyond the Galactocentric radius 45 kpc. They identified 2016 RRL candidates derived from the analysis of archival observations of the Southern Edgeworth-Kuiper Belt Object (SEKBO) survey. We have investigated this result by following up on a subset of 137 candidates with a range of magnitudes (Ṽ14-20) using the Faulkes Telescope (FT) database and confirmed 57 candidates as real RRLs. A cross-match between SEKBO RRL survey and Sloan Digital Sky Survey Data Release-7 (SDSS DR-7) revealed 272 RRL candidates in common. Applying the color selection criteria proposed by Ivezic' et al. (2005) resulted in 193 likely RRLs. The completeness as a function of magnitude was calculated empirically from the combined set of SEKBO RRL candidates from current FT data, SDSS cross-matched data, and the Prior et al. (2009) catalog. This resulted in a spatial density distribution characterized by two power laws with a break radius R within a range between 45 kpc and 50 kpc, similar to the results of Keller et al. We find the power-law slopes for the inner and the outer halo as -2.78+/-0.02 and -5.0+/- 0.2. The SkyMapper telescope survey promises to deliver better quality data for the entire southern hemisphere sky. We quantify the likely efficiency and completeness of the survey as regards the detection of RRL stars via observations of the RRL-rich globular cluster NGC3201. For single-epoch 'uvgri' observations followed by two further epochs of 'gr' imaging, as per the intended 3-epoch survey strategy, we recover known RRLs with >90% efficiency. We also investigate boundaries in the gravity-sensitive single-epoch 2-colour diagram that yield high completeness and high efficiency (i.e. minimal contamination by non-RRLs). The availability of multi-epoch data is one of the big advantages of the SkyMapper survey over SDSS. The primary selection for RRLs in SkyMapper through variability and then location in the gravity sensitive diagram will help to find thousands of RRLs in the southern sky over the entire halo and will likely identify many new substructures. These will make a major contribution to the shape and the extent of the halo and will constrain Galaxy formation models.
Book Synopsis Exploring the Milky Way Halo with SDSS-II SN Survey RR Lyrae Stars by : Nathan De Lee
Download or read book Exploring the Milky Way Halo with SDSS-II SN Survey RR Lyrae Stars written by Nathan De Lee and published by . This book was released on 2008 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Leben der seeligen Kayserin Hildegardis by :
Download or read book Leben der seeligen Kayserin Hildegardis written by and published by . This book was released on 1754 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book RR Lyrae Stars written by Horace A. Smith and published by Cambridge University Press. This book was released on 2004-09-16 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Complete account of the applications of RR Lyrae stars in professional astronomy.
Book Synopsis Mapping the Early Galaxy by : Irina Plaks
Download or read book Mapping the Early Galaxy written by Irina Plaks and published by . This book was released on 2021 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studying stellar populations in the Milky Way's halo is one of several ways that astronomers can gain insight into how the halo formed. By studying the abundances, kinematics, and spatial distributions of the RR Lyrae population, a very old (>10 Gyr) group of variable stars with a particularly short period of less than a day, researchers can understand the conditions present during the Galaxy's formation. These stars are ideal for observation due to their narrowly defined absolute magnitude and distinctive light curves. However, much of the data we have on known RR Lyrae variables is outdated, and with the construction of new telescopes, astronomers now have the opportunity to bring the information up to date. Using data from the All-Sky Automated Survey for SuperNovae (ASAS-SN), we have obtained updated periods for the 106 RR Lyrae stars studied in Layden (1998). With these periods, new light curves were created, providing us with accurate mean magnitudes, epochs of maximum light, and amplitudes. These properties were used along with spectroscopic data to find the distances, radial velocities, and metal abundances of 84 of these stars, from which we then obtained net rotational velocities. The net rotational velocity for all stars in our sample was found to be 36 ℗ł 19 km/s. When these stars were divided into metal-rich halo stars (-1.8 9́Þ [Fe/H]
Book Synopsis Old Stellar Populations by : Santi Cassisi
Download or read book Old Stellar Populations written by Santi Cassisi and published by John Wiley & Sons. This book was released on 2013-08-29 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book discusses the theoretical path to decoding the information gathered from observations of old stellar systems. It focuses on old stellar systems because these are the fossil record of galaxy formation and provide invaluable information ont he evolution of cosmic structures and the universe as a whole. The aim is to present results obtained in the past few years for theoretical developments in low mass star research and in advances in our knowledge of the evolution of old stellar systems. A particularly representative case is the recent discovery of multiple stellar populations in galactic globular clusters that represents one of the hottest topics in stellar and galactic astrophysics and is discussed in detail. Santi Cassisi has authored about 270 scientific papers, 150 of them in peer-reviewed journals, and the title Evolution of Stars and Stellar Populations.
Book Synopsis The Formation of the Milky Way by : E. J. Alfaro
Download or read book The Formation of the Milky Way written by E. J. Alfaro and published by Cambridge University Press. This book was released on 1995-08-03 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: This review examines all the key physical processes involved in the formation and evolution of the Milky Way, based on an international meeting held in Granada (Spain).
Book Synopsis The Evolution of The Milky Way by : F. Matteucci
Download or read book The Evolution of The Milky Way written by F. Matteucci and published by Springer Science & Business Media. This book was released on 2000 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt: This review of the most up-to-date observational and theoretical information concerning the chemical evolution of the Milky Way compares the abundances derived from field stars and clusters, giving information on the abundances and dynamics of gas.
Book Synopsis Stellar Candles for the Extragalactic Distance Scale by : Danielle Alloin
Download or read book Stellar Candles for the Extragalactic Distance Scale written by Danielle Alloin and published by Springer Science & Business Media. This book was released on 2003-10-20 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume reviews the current status with respect to both theory and observation of the extragalactic distance scale. A sufficient accuracy is required both for a precise determination of the cosmological parameters and also in order to achieve a better understanding of physical processes in extragalactic systems. The "standard candles", used to set up the extragalactic distance scale, reviewed in this book include cepheid variables, RR Lyrae variables, novae, Type Ia and Type II supernovae as well as globular clusters and planetary nebulae.
Download or read book Pulsating Stars written by Márcio Catelan and published by John Wiley & Sons. This book was released on 2015-03-23 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book surveys our understanding of stars which change in brightness because they pulsate. Pulsating variable stars are keys to distance scales inside and beyond the Milky Way galaxy. They test our understanding not only of stellar pulsation theory but also of stellar structure and evolution theory. Moreover, pulsating stars are important probes of the formation and evolution of our own and neighboring galaxies. Our understanding of pulsating stars has greatly increased in recent years as large-scale surveys of pulsating stars in the Milky Way and other Local Group galaxies have provided a wealth of new observations and as space-based instruments have studied particular pulsating stars in unprecedented detail.
Book Synopsis Setting the Scene for Gaia and LAMOST (IAU S298) by : Sofia Feltzing
Download or read book Setting the Scene for Gaia and LAMOST (IAU S298) written by Sofia Feltzing and published by Cambridge University Press. This book was released on 2014-01-30 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gaia is an ambitious satellite mission to chart a three-dimensional map of the Milky Way. By measuring the proper motions and parallaxes for a billion stars, Gaia is set to transform the way we study the composition, formation and evolution of our galaxy. Concurrently the LAMOST survey facility in China will make a complementary spectral survey of millions of objects in much of the northern sky. This volume, comprising the reviews and contributed talks presented at IAU Symposium 298, is an up-to-date review of what we know about the Milky Way as a galaxy prior to the launch of Gaia. It covers many topics including the status of dynamical simulations, photometric and spectroscopic surveys, and interstellar matter in the Milky Way, as well as detailed studies of stellar atmospheres. The expert reviews will interest all those working on Milky Way astronomy as well as galaxy formation and evolution.
Book Synopsis Formation of the Galactic Halo-- Inside and Out by : Heather Morrison
Download or read book Formation of the Galactic Halo-- Inside and Out written by Heather Morrison and published by . This book was released on 1996 with total page 592 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Evolution of Stars and Stellar Populations by : Maurizio Salaris
Download or read book Evolution of Stars and Stellar Populations written by Maurizio Salaris and published by John Wiley & Sons. This book was released on 2005-12-13 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evolution of Stars and Stellar Populations is a comprehensive presentation of the theory of stellar evolution and its application to the study of stellar populations in galaxies. Taking a unique approach to the subject, this self-contained text introduces first the theory of stellar evolution in a clear and accessible manner, with particular emphasis placed on explaining the evolution with time of observable stellar properties, such as luminosities and surface chemical abundances. This is followed by a detailed presentation and discussion of a broad range of related techniques, that are widely applied by researchers in the field to investigate the formation and evolution of galaxies. This book will be invaluable for undergraduates and graduate students in astronomy and astrophysics, and will also be of interest to researchers working in the field of Galactic, extragalactic astronomy and cosmology. comprehensive presentation of stellar evolution theory introduces the concept of stellar population and describes "stellar population synthesis" methods to study ages and star formation histories of star clusters and galaxies presents stellar evolution as a tool for investigating the evolution of galaxies and of the universe in general
Book Synopsis Tidal Streams in the Local Group and Beyond by : Heidi Jo Newberg
Download or read book Tidal Streams in the Local Group and Beyond written by Heidi Jo Newberg and published by Springer. This book was released on 2015-12-29 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is written by leading scientists in the field, who review the current state of our knowledge of tidal streams in the Milky Way, the Andromeda galaxy, and in other nearby galaxies. The cosmological origins of dwarf galaxies and the physical processes by which they are tidally disrupted into streams and incorporated into galaxy halos are discussed. The techniques that have been used to identify tidal streams are presented and will be useful to researchers who would like to find substructures in the next generation of optical sky surveys, including Pan-STARRS and LSST. The methods that are currently under development to constrain both large scale distribution of dark matter in the Milky Way and the (small scale) lumpiness of the dark matter distribution are also explained. The authors also provide motivation for future spectroscopic surveys of Milky Way halo stars, which will aid both in the identification of tidal streams and the constraint of dark matter properties. This volume is aimed at graduate students who are beginning this field of research, but is also a resource for researchers who study tidal streams and related fields. In addition to presenting the physical processes by which tidal streams are created, it also reviews the current state of the observations and the progress towards utilizing these observations to constrain the distribution of dark matter in the Milky Way. The book will introduce anyone with a background in astrophysics to the field of tidal streams.
Book Synopsis The Universe at Midnight by : Ken Croswell
Download or read book The Universe at Midnight written by Ken Croswell and published by Simon and Schuster. This book was released on 2002 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the internationally acclaimed author of Magnificent Universe, Ken Croswell, comes the definitive story of the golden age in our understanding of the universe -- the age we live in right now. The universe's origin, evolution, and fate have long fascinated humanity, but until recently these subjects resided in astronomy's never-never land. The last ten years, however, have witnessed a stunning turnabout: an avalanche of new cosmological discoveries that illuminate the greatest questions of all. The Universe at Midnight is a platform from which to observe these new deep-space landmarks. Mammoth new telescopes on Earth, such as the Keck Observatory in Hawaii, the Very Large Telescope in Chile, and Japan's Subaru Telescope, as well as the Hubble Space Telescope overhead, are probing the frontiers of the universe with stunning results. In 1996 astronomers pinpointed the center of the elusive "Great Attractor, " a mass of galaxies 250 million light-years away that is trying to tug our Galaxy andthousands of others across the universe. In late 1997, two teams hunting supernovae in galaxies billions of light-years away shocked their colle
Book Synopsis The Galaxies of the Local Group by : Sidney Bergh
Download or read book The Galaxies of the Local Group written by Sidney Bergh and published by Cambridge University Press. This book was released on 2000-05-15 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Local Group is a small cluster of galaxies that includes the Milky Way. At least half of all galaxies in the Universe are thought to belong to similar groups. This authoritative volume provides a comprehensive synthesis of what is known about the Local Group. It begins with a summary of each member galaxy, as well as those galaxies previously regarded as possible members. The book examines the mass, stability and evolution of the Local Group as a whole and includes many important previously unpublished results and conclusions. With clarity, Professor van den Bergh provides a masterful summary of all that is known about the galaxies of the Local Group and their evolution, and expertly places this knowledge in the wider context of on-going studies of galaxy formation and evolution, the cosmic distance scale, and the conditions in the early Universe.
Book Synopsis Stellar Populations by : Piet C. van der Kruit
Download or read book Stellar Populations written by Piet C. van der Kruit and published by Springer Science & Business Media. This book was released on 2013-12-01 with total page 463 pages. Available in PDF, EPUB and Kindle. Book excerpt: The concept of Stellar Populations has played a fundamental role in astronomy in the last few decades. It was introduced by Walter Baade after he was able to resolve the Andromeda Nebula and its companions into stars when he used red-sensitive plates and realised that there were two fundamentally different Herzsprung-Russell diagrams in our and these nearby galaxies (common stars in the solar neighborhood versus globular clusters). This result was published in two papers in 1944 in volume 100 of the Astrophysical Journal. Subsequent research gave the concept a much firmer basis and at the famous Vatican Symposium of 1957 resulted in a general scheme of the concept and a working hypothesis for idea's on the formation and evolution of the Galaxy. This has been a guiding principle of studies of our and other galaxies for decades. Some years ago it seemed to us appropriate to commemorate Baade's seminal work in 1994, when it would have its 50-th anniversary, and to review its present status and also its role in contempory understanding. While we were in Leiden for an administrative committee, we discussed the matter again and over beers on October 29, 1991 we decided the take the initiative for an IAU Symposium on the subject during the 1994 IAU General Assembly in Den Haag, the Netherlands.
