Author: Courtney Rose Epstein Publisher: ISBN: Category : Languages : en Pages : 140
Book Description
Rotation periods are predicted to be a useful clock and detectable by ground-based surveys for field populations as old as 1-2 Gyr, and detectable by space-based telescopes for stars as old as the Galactic disk. Rotation provides better leverage than other age diagnostics for unevolved dwarfs because the spin down timescale is much faster than the nuclear-burning timescale. However, for solar-like dwarfs and more evolved stars, asteroseismology (the study of stellar interiors through global oscillations) can achieve more precise age estimates.
Author: Andreia Jessica Arabani Carrillo Publisher: ISBN: Category : Languages : en Pages : 484
Book Description
No other astronomical object can unlock the mysteries of the Universe more than stars. Studying the crowded, unresolved stellar populations of nearby galaxies aids in understanding what brings about their observed properties, morphology, activity, and assembly history. Studying the Milky Way’s resolved stellar populations, specifically their detailed chemical abundances and kinematics, provides us with an unparalleled, zoomed-in view of galaxy formation. Additionally, understanding Milky Way stellar populations can supplement our knowledge in other fields in Astronomy, such as exoplanet populations, as the gas that forms a star also forms the planets around it. This is the focus of my dissertation: analyzing stellar populations--both resolved in the Milky Way (observed and simulated) and unresolved in a nearby galaxy--to holistically understand galaxy formation, the Milky Way assembly, and the Galactic context of exoplanet demographics. This Thesis is structured going from the largest and farthest of scales e.g. external galaxy, to the smallest of scales e.g. planet-hosting stars. With unresolved, ensemble stellar populations, I investigate the assembly of the different components: the bulge, bar, and disc, of the nearby galaxy NGC 2903, using the VIRUS-P Exploration of Nearby Galaxies (VENGA) Integral Field Spectroscopy (IFS) survey. This work benefited from high signal-to-noise, spatially-resolved spectroscopic data that enabled me to construct a more comprehensive picture of NGC 2903’s formation history by understanding the growth of its different components. Moving closer to the Milky Way and unveiling the history of its halo, I present a detailed chemical study for stars from one of Milky Way’s most significant mergers dubbed Gaia-Enceladus-Sausage (GES), aided by high-resolution optical spectra from McDonald Observatory and Magellan Telescope. I contrast these stars’ abundance trends to those found in the Milky Way and its surviving satellites to understand how its chemical signatures compare to other stellar populations and what this tells us about its star formation history. As emphasized in this Thesis, it is important to investigate galaxy assembly through the lenses of different galaxy components and in an interdisciplinary way. Therefore, I also aim to understand the formation of the Milky Way disc. I do this by turning to a zoom-in cosmological simulation of a Milky Way mass galaxy from the FIRE-2 suite and where I determine how the ages, metallicities, and detailed chemical abundances of stars relate to each other and to their current and birth locations. Specifically, I investigate if the stars in the simulations exhibit a tight age-abundance trend, similar to what is found in observations. Further, I explore how the dispersion found around this trend, at different metallicities and locations in the galaxy, relates to the star formation history of the simulated Milky Way. Lastly, taking advantage of the power of Milky Way large surveys, I kinematically and chemically characterized targets from the Transiting Exoplanet Survey Satellite (TESS) to understand the Galactic context of planet-hosting stars. This is especially important as we find more exoplanets in different parts of the Galaxy, enabling us to understand if and how planet formation and demographics are different for different Milky Way stellar populations. The accomplishments of this Thesis have contributed to a broad range of fields in Astronomy, but all tied together by the analysis of stellar populations in the Milky Way and beyond
Author: E. J. Alfaro Publisher: Cambridge University Press ISBN: 9780521481779 Category : Science Languages : en Pages : 384
Book Description
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).
Author: Maurizio Salaris Publisher: John Wiley & Sons ISBN: 9780470092224 Category : Science Languages : en Pages : 386
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: Benjamin Frank Bubnick Publisher: ISBN: Category : Languages : en Pages : 99
Book Description
This thesis outlines successful efforts for identifying and characterizing the stellar content of two Galactic disk star clusters using near-infrared observations. Astronomers have a great wealth of knowledge about Globular Clusters. They are easy to see as most lie outside the plane of the galaxy, in the halo. Extinction is low, stellar population is dense in the cluster, and they are fairly common. However, in the plane of the galaxy, relatively little is known of the open cluster population. Galactic disk open clusters, such as the two discussed in this thesis, are hidden behind gas, dust, and projected against a multitude of field stars. Through the use of near-infrared broad-band photometry and spectroscopy, the distance, age and approximate mass of two disk clusters has been determined.
Author: Francesca Matteucci Publisher: Springer Science & Business Media ISBN: 9401009384 Category : Science Languages : en Pages : 605
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: National Research Council Publisher: National Academies Press ISBN: 0309157994 Category : Science Languages : en Pages : 324
Book Description
Driven by discoveries, and enabled by leaps in technology and imagination, our understanding of the universe has changed dramatically during the course of the last few decades. The fields of astronomy and astrophysics are making new connections to physics, chemistry, biology, and computer science. Based on a broad and comprehensive survey of scientific opportunities, infrastructure, and organization in a national and international context, New Worlds, New Horizons in Astronomy and Astrophysics outlines a plan for ground- and space- based astronomy and astrophysics for the decade of the 2010's. Realizing these scientific opportunities is contingent upon maintaining and strengthening the foundations of the research enterprise including technological development, theory, computation and data handling, laboratory experiments, and human resources. New Worlds, New Horizons in Astronomy and Astrophysics proposes enhancing innovative but moderate-cost programs in space and on the ground that will enable the community to respond rapidly and flexibly to new scientific discoveries. The book recommends beginning construction on survey telescopes in space and on the ground to investigate the nature of dark energy, as well as the next generation of large ground-based giant optical telescopes and a new class of space-based gravitational observatory to observe the merging of distant black holes and precisely test theories of gravity. New Worlds, New Horizons in Astronomy and Astrophysics recommends a balanced and executable program that will support research surrounding the most profound questions about the cosmos. The discoveries ahead will facilitate the search for habitable planets, shed light on dark energy and dark matter, and aid our understanding of the history of the universe and how the earliest stars and galaxies formed. The book is a useful resource for agencies supporting the field of astronomy and astrophysics, the Congressional committees with jurisdiction over those agencies, the scientific community, and the public.
Author: Leo Blitz Publisher: Springer Science & Business Media ISBN: 9401128138 Category : Science Languages : en Pages : 175
Book Description
Our view of our Galaxy has recently been undergoing an increasing divergence from the traditional standpoint. In this book ten authors discuss in eight chapters how the conceptions of the Milky Way have moved in new directions. Starting with the inner parsec and the Center of the Galaxy, the book gradually moves on to the bulge and its relation to the globular clusters and to the disk, of which the presence of a bar is argued. A new look on the HI distribution in the disk, a synthesis of molecular line surveys and the study of stellar populations are discussed in the last three chapters.
Author: William J. Wainwright Publisher: ISBN: Category : Stars Languages : en Pages : 0
Book Description
"Stellar clusters provide a unique look into the populations of stars in our galaxy through different slices of time. The evolution of a population of stars is highly subject to initial conditions, and as such, through careful observation and rigorous analysis, one can infer those initial conditions from the comparison to models. In this work, we present our methods and findings on the process of filtering, fitting, and statistical analysis of 17 nearby open clusters. For each cluster, we have confidently identified cluster members before fitting thousands of permutations of synthetic isochrones and color excess to determine the best fit. We present Gaia-based ages, metallicities, membership counts, and interstellar reddening of 17 open clusters. For 6 of these clusters, we are the first to present Gaia-based determinations of the aforementioned properties. Additionally, we analyze the surface density and average mass drop-off of each open cluster. Finally, we delve into the population statistics of open clusters in the Milky Way, showing correlations such as mean cluster mass as a function of age."--Abstract.
Author: Shaila Akhter Publisher: ISBN: Category : Galactic halos Languages : en Pages : 152
Book Description
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.
Author: Courtney Rose Epstein
Author: Andreia Jessica Arabani Carrillo
Author: E. J. Alfaro
Author: Maurizio Salaris
Author: Benjamin Frank Bubnick
Author: Francesca Matteucci
Author: National Research Council
Author: Leo Blitz
Author: William J. Wainwright
Author: Shaila Akhter