Ages and Abundances of Local Galactic Stellar Populations PDF Download
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Author: Diane K. Feuillet
Publisher:
ISBN:
Category : Cosmic abundances
Languages : en
Pages : 530
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Book Description
The chemical compositions of stellar atmospheres reflect the interstellar gas from which they formed, each one containing a snapshot of the Milky Way Galaxy’s chemical evolution. By comparing abundances of stars across the disk of our Galaxy, we can explore how different parts of the Galaxy were enriched, where star formation proceeded most rapidly, and whether there has been significant mixing of stars and gas through the disk. In general, older stars formed from material that had fewer metals and younger stars formed after more metals had been deposited into the interstellar medium. However, the relative dating of stars based on metallicity cannot easily be mapped to an absolute age, and the local age-metallicity relation cannot be used in different Galactic locations. The rate of metal enrichment depends strongly on the star formation rate. To use the full power of studying stellar atmosphere compositions across the Galaxy, we also need to determine absolute stellar ages. In this dissertation, I examine the ages and chemical abundances of stars in the solar neighborhood with the goal of extending this analysis to the larger APOGEE sample, which spans the full Milky Way disk. Through an independent analysis of optical spectra of APOGEE stars, I validate the individual chemical abundances measured by the near-infrared spectroscopic survey. The main stellar targets of APOGEE are red giant stars, for which the atmospheric parameters are degenerate with age. I develop a method of constraining the age distribution of a sample of giants, and determining individual ages to 0.1 dex, using a sample of local red giant stars with well measured distance. For the solar neighborhood, I find that the mean age of the sample is closely correlated with the abundance of [alpha]-elements in the stars, even at young ages. Using a sample of local subgiant stars, for which ages can be more precisely measured, I confirm this result for the solar neighborhood. I conclude that the method presented here for finding ages of red giant stars with known distances can robustly be applied to the full APOGEE sample for which distances will soon be available from the Gaia mission.
Author: Diane K. Feuillet
Publisher:
ISBN:
Category : Cosmic abundances
Languages : en
Pages : 530
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Book Description
The chemical compositions of stellar atmospheres reflect the interstellar gas from which they formed, each one containing a snapshot of the Milky Way Galaxy’s chemical evolution. By comparing abundances of stars across the disk of our Galaxy, we can explore how different parts of the Galaxy were enriched, where star formation proceeded most rapidly, and whether there has been significant mixing of stars and gas through the disk. In general, older stars formed from material that had fewer metals and younger stars formed after more metals had been deposited into the interstellar medium. However, the relative dating of stars based on metallicity cannot easily be mapped to an absolute age, and the local age-metallicity relation cannot be used in different Galactic locations. The rate of metal enrichment depends strongly on the star formation rate. To use the full power of studying stellar atmosphere compositions across the Galaxy, we also need to determine absolute stellar ages. In this dissertation, I examine the ages and chemical abundances of stars in the solar neighborhood with the goal of extending this analysis to the larger APOGEE sample, which spans the full Milky Way disk. Through an independent analysis of optical spectra of APOGEE stars, I validate the individual chemical abundances measured by the near-infrared spectroscopic survey. The main stellar targets of APOGEE are red giant stars, for which the atmospheric parameters are degenerate with age. I develop a method of constraining the age distribution of a sample of giants, and determining individual ages to 0.1 dex, using a sample of local red giant stars with well measured distance. For the solar neighborhood, I find that the mean age of the sample is closely correlated with the abundance of [alpha]-elements in the stars, even at young ages. Using a sample of local subgiant stars, for which ages can be more precisely measured, I confirm this result for the solar neighborhood. I conclude that the method presented here for finding ages of red giant stars with known distances can robustly be applied to the full APOGEE sample for which distances will soon be available from the Gaia mission.
Author: Maurizio Salaris
Publisher: John Wiley & Sons
ISBN: 9780470092224
Category : Science
Languages : en
Pages : 386
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Book Description
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
Author: International Astronomical Union. Symposium
Publisher: Cambridge University Press
ISBN: 9780521764841
Category : Galaxies
Languages : en
Pages : 488
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Book Description
IAU Symposium 262 presents reviews on the current understanding of the theories of stellar evolution, galaxy formation and galaxy evolution. It emphasises what we have learned in the past few years from massive surveys covering large portions of the sky (e.g. SDSS, HDF, UDF, GOODS, COSMOS). Several critical aspects of research on stellar populations deserve further effort in order to be brought in tune with other areas of astrophysical research. The next ten years will see the opening of major observatories that will increase the quality and quantity of astronomical data by orders of magnitude. The expected benefits from these instruments for the study of stellar populations are explored. This critical review of state of the art observational and theoretical work will appeal to all those working on stellar populations, from distant galaxies to local resolved galaxies and galactic star clusters.
Author: Piet C. van der Kruit
Publisher: Springer Science & Business Media
ISBN: 9401101256
Category : Science
Languages : en
Pages : 463
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Book Description
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.
Author: A. Aparicio
Publisher: Cambridge University Press
ISBN: 9780521632553
Category : Science
Languages : en
Pages : 628
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Book Description
A review of the new subject of extragalactic stellar astrophysics - for both graduate students and researchers working in astrophysics.
Author: Space Telescope Science Institute (U.S.). Symposium
Publisher: Cambridge University Press
ISBN: 9780521847599
Category : Science
Languages : en
Pages : 248
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Book Description
Publisher description
Author: Colin A. Norman
Publisher: Cambridge University Press
ISBN: 9780521333801
Category : Nature
Languages : en
Pages : 264
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Book Description
A comprehensive survey of stellar populations traces them from initial mass function and star formation histories through the chemical history of galaxies and their observed evolution.
Author: B. Barbuy
Publisher: Springer Science & Business Media
ISBN: 9401124345
Category : Science
Languages : en
Pages : 529
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Book Description
One approach to learning about stellar populations is to study them at three different levels of resolution. First in our own Galaxy; secondly from nearby galaxies where stars can still be resolved; and thirdly in remote galaxies in which the stellar population can only be studied in integrated light. This IAU Symposium covered the entire range of galaxies in its study of their stellar populations. Interspersed with theoretical papers, the wealth of observational results provides an important state-of-the-art presentation of the progress that has been made in this field.
Author: F. Matteucci
Publisher: Springer Science & Business Media
ISBN: 9780792366799
Category : Medical
Languages : en
Pages : 644
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Book Description
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.
Author: Sidney Bergh
Publisher: Cambridge University Press
ISBN: 1139429655
Category : Science
Languages : en
Pages : 348
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Book Description
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.
