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We combine the estimated metallicities [Fe/H], abundances [\alpha/Fe], positions and motions of a sample of 27,500 local (7<R/kpc<9, 0.5<|z|/kpc<2.5) SDSS/SEGUE G-type dwarf stars to investigate the chemo-orbital properties of the Milky…

星系天体物理 · 物理学 2015-06-03 Chao Liu , Glenn van de Ven

We present Galactic mean metallicity maps derived from the first year of the SDSS-III APOGEE experiment. Mean abundances in different zones of Galactocentric radius (0 < R < 15 kpc) at a range of heights above the plane (0 < |z| < 3 kpc),…

We aim to quantify the chemical and kinematical properties of the Galactic disks with a sample of 119,558 giant stars having abundances and 3D velocities taken or derived from the APOGEE DR17 and Gaia EDR3 catalogs. The Gaussian Mixture…

星系天体物理 · 物理学 2022-04-20 Guozhen Hu , Zhengyi Shao

We explored a method to reconstruct the distribution function of the Galactic thick disc within the action space where nearby thick-disc stars are distributed. By applying this method to 127 chemically-selected thick-disc stars in the Solar…

星系天体物理 · 物理学 2015-09-30 Kohei Hattori , Gerard Gilmore

The evolution of the Milky Way bulge and its relationship with the other Galactic populations is still poorly understood. The bulge has been suggested to be either a merger-driven classical bulge or the product of a dynamical instability of…

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

Most high-resolution spectroscopic studies of the Galactic discs were mostly confined to objects in the solar vicinity. Here we aim at enlarging the volume in which individual chemical abundances are used to characterise both discs, using…

The behavior of the relative magnesium abundances in the thin-disk stars versus their orbital radii suggests that the star formation rate in the thin disk decreases with increasing Galactocentric distance, and there was no star formation…

天体物理学 · 物理学 2007-10-29 V. A. Marsakov , M. V. Shapovalov , T. V. Borkova

Edge on systems reveal the properties of disk galaxies as a function of height, z, above the plane. Four local edge-on galaxies, that are close enough to have been resolved into stars by the Hubble Space Telescope, show thick disks,…

天体物理学 · 物理学 2009-11-10 Jeremy Mould

We show that there are strong local correlations between metallicity, surface brightness, and dynamical mass-to-light ratio within M33, analogous to the fundamental line of dwarf galaxies identified by Prada & Burkert (2002). Using…

天体物理学 · 物理学 2008-11-26 Joshua D. Simon , Francisco Prada , Jose M. Vilchez , Leo Blitz , Brant Robertson

In the search of a sample of metal-poor bright giants using Str{\"o}mgren photometry, we serendipitously found a sample of 26 young (ages younger than 1 Gyr) metal-rich giants, some of which have high rotational velocities.We determined the…

Using the FIRE-2 cosmological zoom-in simulations, we investigate the temporal evolution of gas-phase metallicity radial gradients of Milky Way-mass progenitors in the redshift range of $0.4<z<3$. We pay special attention to the occurrence…

Thick disks are a prevalent feature observed in numerous disk galaxies including our own Milky Way. Their significance has been reported to vary widely, ranging from a few to 100% of the disk mass, depending on the galaxy and the…

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

Using nearly 230,000 red clump (RC) stars selected from LAMOST and Gaia, we conduct a comprehensive analysis of the stellar age-velocity dispersion relations (AVRs) for various disk populations, within 5.0 $\leq$ $R$ $\leq$ 15.0 kpc and…

星系天体物理 · 物理学 2025-01-07 Weixiang Sun , Han Shen , Biwei Jiang , Xiaowei Liu

We investigate, using the Gaia-ESO Survey internal Data-Release 2, the properties of the double sequence of the Milky Way discs (defined chemically as the high-alpha and low-alpha populations), and discuss their compatibility with discs…

Based on the data release of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope survey (LAMOST DR5) and the \emph{Gaia} Early Data Release 3 (\emph{Gaia} EDR3), we construct a sample containing 46,109 giant (log~$\emph{g}$…

星系天体物理 · 物理学 2022-02-16 T. -S. Yan , J. -R. Shi , H. Tian , W. Zhang , B. Zhang

We derive the vertical velocities of disk stars in the range of Galactocentric radii of R=5-16 kpc within 2 kpc in height from the Galactic plane. This kinematic information is connected to dynamical aspects in the formation and evolution…

星系天体物理 · 物理学 2014-12-10 M. Lopez-Corredoira , H. Abedi , F. Garzon , F. Figueras

(Abridged) We perform an analysis of spectra and photometry for 22,770 stars included in the third data release (DR3) of the SDSS. We measure radial velocities and, based on a model-atmosphere analysis, derive estimates ofthe atmospheric…

天体物理学 · 物理学 2009-09-29 C. Allende Prieto , T. C. Beers , R. Wilhelm , H. J. Newberg , C. M. Rockosi , B. Yanny , Y. S. Lee

We investigate the chemo-kinematic properties of the Milky Way disc by exploring the first year of data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE), and compare our results to smaller optical high-resolution…