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We search for the existence of chemically-distinct stellar components in the solar neighbourhood using published data. Extending earlier work, we show that when the abundances of Fe, alpha elements, and the r-process element Eu are…

星系天体物理 · 物理学 2015-05-19 Julio F. Navarro , Mario G. Abadi , Kim A. Venn , Kenneth C. Freeman , Borja Anguiano

The present day chemical and dynamical properties of the Milky Way bear the imprint of the Galaxy's formation and evolutionary history. One of the most enduring and critical debates surrounding Galactic evolution is that regarding the…

天体物理学 · 物理学 2009-11-07 Chris B. Brook , Daisuke Kawata , Brad K. Gibson , Chris Flynn

We develop a new method to account for the finite lifetimes of stars and trace individual abundances within a semi-analytic model of galaxy formation. At variance with previous methods, based on the storage of the (binned) past star…

Small stellar systems like dwarf galaxies are suggested to be the main building blocks of our Galaxy by numerical simulations in Lambda CDM models. The existence of star streams like Sagittarius tidal stream indicates that dwarf galaxies…

太阳与恒星天体物理 · 物理学 2019-05-13 Qian-Fan Xing , Gang Zhao , Wako Aoki , Satoshi Honda , Hai-Ning Li , Miho N. Ishigaki , Tadafumi Matsuno

We analyse a set of very metal-poor stars for which accurate chemical abundances have been obtained as part of the ESO Large Program "First stars" in the light of the Gaia DR2 data. The kinematics and orbital properties of the stars in the…

星系天体物理 · 物理学 2020-04-29 P. Di Matteo , M. Spite , M. Haywood , P. Bonifacio , A. Gómez , F. Spite , E. Caffau

We analyze high quality abundances data of solar neighborhood stars and show that there are two distinct regimes of [alpha/Fe] versus age which we identify as the epochs of the thick and thin disk formation. A tight correlation between…

星系天体物理 · 物理学 2015-06-16 M. Haywood , P. Di Matteo , M. Lehnert , D. Katz , A. Gomez

We analyse the chemical properties of a set of solar vicinity stars, and show that the small dispersion in abundances of \alpha-elements at all ages provides evidence that the SFH has been uniform throughout the thick disk. In the context…

星系天体物理 · 物理学 2015-04-13 M. Haywood , P. Di Matteo , O. Snaith , M. Lehnert

We present chemical abundance analyses of sodium, iron-peak and neutron-capture elements for 97 kinematically selected thick disk, inner halo and outer halo stars with metallicities -3.3<[Fe/H]<-0.5. The main aim of this study is to examine…

星系天体物理 · 物理学 2015-06-16 Miho N. Ishigaki , Wako Aoki , Masashi Chiba

The age distribution, and chemical elemental abundances, of stars in the halo of the Milky Way provide constraints on theories of galaxy formation. As one specific example, the accretion of satellite galaxies similar to the present retinue…

天体物理学 · 物理学 2015-06-24 M. Unavane , R. F. G. Wyse , G. F. Gilmore

We analyze the observed spatial, chemical and dynamical distributions of local metal-poor stars, based on photometrically derived metallicity and distance estimates along with proper motions from the Gaia mission. Along the Galactic prime…

星系天体物理 · 物理学 2021-09-29 Deokkeun An , Timothy C. Beers

It is well-established that the vast majority of metal-poor Galactic halo stars shows evidence for enrichment by solely massive stars. Recent observations have identified more varied behavior in the pattern of elemental abundances measured…

天体物理学 · 物理学 2016-08-30 Gerard Gilmore , Rosemary F. G. Wyse

We present the results of a detailed abundance analysis of one of the confirmed building blocks of the Milky Way stellar halo, a kinematically-coherent metal-poor stellar stream. We have obtained high resolution and high S/N spectra of 12…

星系天体物理 · 物理学 2015-05-14 Ian U. Roederer , Christopher Sneden , Ian B. Thompson , George W. Preston , Stephen A. Shectman

We report the results of an unsupervised decomposition of the local stellar halo in the chemo-dynamical space spanned by the abundance measurements from APOGEE DR17 and GALAH DR3. In our Gaussian Mixture Model, only four independent…

星系天体物理 · 物理学 2023-01-31 G. C. Myeong , Vasily Belokurov , David S. Aguado , N. Wyn Evans , Nelson Caldwell , James Bradley

We use the first Gaia data release, combined with RAVE and APOGEE spectroscopic surveys, to investigate the origin of halo stars within <~3 kpc from the Sun. We identify halo stars kinematically, as moving with a relative speed of at least…

星系天体物理 · 物理学 2017-08-30 Ana Bonaca , Charlie Conroy , Andrew Wetzel , Philip F. Hopkins , Dusan Keres

We continue our series of papers on phase-space distributions of stars in the Milky Way based on photometrically derived metallicities and Gaia astrometry, with a focus on the halo-disk interface in the local volume. To exploit various…

星系天体物理 · 物理学 2023-07-26 Deokkeun An , Timothy C. Beers , Young Sun Lee , Thomas Masseron

We study the radial dependence in stellar populations of 33 nearby early-type galaxies with central stellar velocity dispersions sigma* > 150 km/s. We measure stellar population properties in composite spectra, and use ratios of these…

宇宙学与河外天体物理 · 物理学 2015-06-16 Jenny E Greene , Jeremy D Murphy , Genevieve J Graves , James E Gunn , Sudhir Raskutti , Julia M Comerford , Karl Gebhardt

We improve the identification and isolation of individual stellar populations in the Galactic halo based on an updated set of empirically calibrated stellar isochrones in the Sloan Digital Sky Survey (SDSS) and Pan-STARRS 1 (PS1)…

星系天体物理 · 物理学 2021-02-10 Deokkeun An , Timothy C. Beers

Massive disk galaxies like our Milky Way should host an ancient, metal-poor, and centrally concentrated stellar population. This population reflects the star formation and enrichment in the few most massive progenitor components that…

We use cosmological, chemo-dynamical, smoothed particle hydrodynamical simulations of Milky-Way-analogue galaxies to find the expected present-day distributions of both metal-free stars that formed from primordial gas and the oldest star…

天体物理学 · 物理学 2011-02-11 Chris B. Brook , Daisuke Kawata , Evan Scannapieco , Hugo Martel , Brad K. Gibson

Fully cosmological, high resolution N-Body + SPH simulations are used to investigate the chemical abundance trends of stars in simulated stellar halos as a function of their origin. These simulations employ a physically motivated supernova…

星系天体物理 · 物理学 2015-05-18 Adi Zolotov , Beth Willman , Alyson Brooks , Fabio Governato , David W. Hogg , Sijing Shen , James Wadsley