The Stellar Velocity Distribution Function in the Milky Way Galaxy

The stellar velocity distribution function in the solar vicinity is reexamined using data from the Sloan Digital Sky Survey Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey's DR16 and Gaia DR2. By exploiting APOGEE's ability to chemically discriminate with great relia...

Full description

Saved in:
Bibliographic Details
Published in:The Astronomical journal 2020-07, Vol.160 (1), p.43
Main Authors: Anguiano, Borja, Majewski, Steven R., Hayes, Christian R., Prieto, Carlos Allende, Cheng, Xinlun, Bidin, Christian Moni, Beaton, Rachael L., Beers, Timothy C., Minniti, Dante
Format: Article
Language:English
Subjects:
Astronomy
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Density
DISTRIBUTION FUNCTIONS
GALACTIC EVOLUTION
Galaxies
Galaxy distribution
METALS
MILKY WAY
Milky Way Galaxy
Populations
RELIABILITY
Sky surveys
Sky surveys (astronomy)
STARS
Stellar kinematics
Stellar models
THREE-DIMENSIONAL CALCULATIONS
VELOCITY
Velocity distribution
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The stellar velocity distribution function in the solar vicinity is reexamined using data from the Sloan Digital Sky Survey Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey's DR16 and Gaia DR2. By exploiting APOGEE's ability to chemically discriminate with great reliability the thin-disk, thick-disk, and (accreted) halo populations, we can, for the first time, derive the three-dimensional velocity distribution functions (DFs) for these chemically separated populations. We employ this smaller but more data-rich APOGEE+Gaia sample to build a data-driven model of the local stellar population velocity DFs and use these as basis vectors for assessing the relative density proportions of these populations over the 5 < R < 12 kpc and −1.5 < z < 2.5 kpc range as derived from the larger, more complete (i.e., all-sky, magnitude-limited) Gaia database. We find that 81.9% 3.1% of the objects in the selected Gaia data set are thin-disk stars, 16.6% 3.2% are thick-disk stars, and 1.5% 0.1% belong to the Milky Way stellar halo. We also find the local thick-to-thin-disk density normalization to be T(R )/ t(R ) = 2.1% 0.2%, a result consistent with, but determined in a completely different way from, typical star-count/density analyses. Using the same methodology, the local halo-to-disk-density normalization is found to be H(R )/( T(R ) + t(R )) = 1.2% 0.6%, a value that may be inflated due to the chemical overlap of halo and metal-weak thick-disk stars.
ISSN:0004-6256
1538-3881
1538-3881
DOI:10.3847/1538-3881/ab9813