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We construct a dynamical model of the Milky Way disk from a data set, which combines Gaia EDR3 and APOGEE data throughout Galactocentric radii between $5.0\leq R\leq19.5$ kpc. We make use of the spherically-aligned Jeans Anisotropic Method…

Astrophysics of Galaxies · Physics 2021-08-05 Maria Selina Nitschai , Anna-Christina Eilers , Nadine Neumayer , Michele Cappellari , Hans-Walter Rix

Analytic distribution functions (DFs) for the Galactic disc are discussed. The DFs depend on action variables and their predictions for observable quantities are explored under the assumption that the motion perpendicular to the Galactic…

Astrophysics of Galaxies · Physics 2015-05-14 James Binney

We obtain a new determination of the metallicity distribution function (MDF) of stars within $\sim5$-$10$ kpc of the Sun, based on recently improved co-adds of $ugriz$ photometry for Stripe 82 from the Sloan Digital Sky Survey. Our new…

Understanding the history and the evolution of the Milky Way disc is one of the main goals of modern astrophysics. We study the velocity dispersion behaviour of Galactic disc stars as a function of the [Mg/Fe] ratio, which can be used as a…

We have mapped the number density and mean vertical velocity of the Milky Way's stellar disk out to roughly two kiloparsecs from the Sun using Gaia Data Release 3 (DR3) and complementary photo-astrometric distance information from…

Astrophysics of Galaxies · Physics 2022-12-14 Axel Widmark , Lawrence M. Widrow , Aneesh Naik

We present an updated version of the semi-analytic Just-Jahrei{\ss} (JJ) model of the Galactic disk and constrain its parameters in the Solar neighbourhood. The new features of the JJ model include a simple two-component gaseous disk, a…

Astrophysics of Galaxies · Physics 2021-03-10 K. Sysoliatina , A. Just

We use the Stripe 82 proper motion catalogue of Bramich et al. (2008) to study the kinematics of Galactic disk stars in the solar neighborhood. We select samples of dwarf stars with reliable spectra and proper motions. They have cylindrical…

Astrophysics of Galaxies · Physics 2012-02-08 Martin C. Smith , S. Hannah Whiteoak , N. W. Evans

Abridged: We estimate the distances to ~48 million stars detected by the Sloan Digital Sky Survey and map their 3D number density distribution in 100 < D < 20 kpc range over 6,500 deg^2 of sky. The data show strong evidence for a Galaxy…

Local stellar motions are expected, and have been shown, to include signatures of the Galaxy's past dynamical evolution. These are typically divided into the disc, which shows the dynamical effects of spiral arms and the bar, and the…

Astrophysics of Galaxies · Physics 2022-12-26 Daniel Mikkola , Paul J. McMillan , David Hobbs

We measure the luminosity function (LF) of the Milky Way's stellar halo, using a magnitude complete, distance limited sample of stars from $Gaia$ DR3. Stars with high transverse velocities are selected, to isolate a high purity sample of…

Astrophysics of Galaxies · Physics 2026-03-13 Sarah A. Bird , Chris Flynn , Rudra Sekhri , Hai-Jun Tian , Juntai Shen , Xiang-Xiang Xue , Chao Liu , Gang Zhao

(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…

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

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)…

Astrophysics of Galaxies · Physics 2021-02-10 Deokkeun An , Timothy C. Beers

To illustrate the potential of GDR2, we provide a first look at the kinematics of the Milky Way disc, within a radius of several kiloparsecs around the Sun. We benefit for the first time from a sample of 6.4 million F-G-K stars with full 6D…

We measure the three components of velocity dispersion, $\sigma_{R},\sigma_{\theta},\sigma_{\phi}$, for stars within 6 < R < 30 kpc of the Milky Way using a new radial velocity sample from the MMT telescope. We combine our measurements with…

Astrophysics of Galaxies · Physics 2015-11-11 Charles King , Warren R. Brown , Margaret J. Geller , Scott J. Kenyon

We determine the total dynamical density in the solar neighbourhood using the Tycho-Gaia Astrometric Solution (TGAS) catalogue. Astrometric measurements of proper motion and parallax of stars inform us of both the stellar number density…

Astrophysics of Galaxies · Physics 2019-11-04 Axel Widmark , Giacomo Monari

We explore the phase-space structure of nearby halo stars identified kinematically from Gaia DR2 data. We focus on their distribution in velocity and in "integrals of motion" space as well as on their photometric properties. Our sample of…

Astrophysics of Galaxies · Physics 2018-06-27 Helmer H. Koppelman , Amina Helmi , Jovan Veljanoski

We use FIRE-2 zoom simulations of Milky Way size disk galaxies to derive easy-to-use relationships between the observed circular speed of the Galaxy at the Solar location, $v_\mathrm{c}$, and dark matter properties of relevance for direct…

Astrophysics of Galaxies · Physics 2024-08-15 Patrick G. Staudt , James S. Bullock , Michael Boylan-Kolchin , David Kirkby , Andrew Wetzel , Xiaowei Ou

We use Gaia photometry and astrometry to estimate the vertical spatial structure of the Milky Way at the Solar radius, formally accounting for sample incompleteness (the selection function) and parallax measurement uncertainty. Our results…

Astrophysics of Galaxies · Physics 2022-02-16 Andrew Everall , Vasily Belokurov , N. Wyn Evans , Douglas Boubert , Robert J. J. Grand

We present a novel, data-driven analysis of Galactic dynamics, using unsupervised machine learning -- in the form of density estimation with normalizing flows -- to learn the underlying phase space distribution of 6 million nearby stars…

Astrophysics of Galaxies · Physics 2025-12-05 Sung Hak Lim , Eric Putney , Matthew R. Buckley , David Shih

We investigate the structure of our Galaxy's young stellar disc by fitting the distribution functions (DFs) of a new family to five-dimensional Gaia data for a sample of $47\,000$ OB stars. Tests of the fitting procedure show that the young…

Astrophysics of Galaxies · Physics 2022-07-20 Chengdong Li , James Binney
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