On the Kinematic Signature of the Galactic Warp As Revealed By the LAMOST-TGAS Data
Abstract
Using a sample of about 123,000 stars with accurate 3D velocity measurements from the LAMOST-TGAS data, we confirm the kinematic signature of the Galactic warp recently found by Schönrich & Dehnen. The data reveal a clear trend of increasing mean vertical velocity \overline{{V}z} as a function of absolute vertical angular momentum L z and azimuthal velocity V ϕ for guiding center radius R g between 6.0 and 10.5 kpc. The trend is consistent with a large-scale Galactic warp. Similar to Schönrich & Dehnen, we also find a wave-like pattern of \overline{{V}z} versus L z with an amplitude of ∼0.9 km s-1 on a scale of ∼2.0 kpc, which could arise from bending waves or a winding warp. Finally, we confirm a prominent, localized peak in \overline{{V}z} near L z ∼ 2150 kpc km s-1 (corresponding to R g ∼ 9 kpc and V ϕ ∼ 255 km s-1). The additional line-of-sight velocity information from LAMOST reveals that stars in this feature have a large, inward radial velocity of V R ∼ -13.33 ± 0.59 km s-1 and a small radial velocity dispersion of σ R ∼ 25.27 ± 0.89 km s-1, suggesting that a stellar stream gives rise to this feature.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2018
- DOI:
- 10.3847/1538-4357/aad285
- arXiv:
- arXiv:1807.02920
- Bibcode:
- 2018ApJ...864..129H
- Keywords:
-
- Galaxy: kinematics and dynamics;
- Galaxy: structure;
- solar neighborhood;
- stars: distances;
- stars: kinematics and dynamics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- ApJ accepted, 7 pages, 6 figures