Parameters of the Local Warp of the Stellar-Gaseous Galactic Disk from the Kinematics of Tycho-2 Nearby Red Giant Clump Stars

Abstract

We analyze the three-dimensional kinematics of about 82000 Tycho-2 stars belonging to the red giant clump (RGC). First, based on all of the currently available data, we have determined new, most probable components of the residual rotation vector of the optical realization of the ICRS/HIPPARCOS system relative to an inertial frame of reference, ω_x,ω_y,ω_z)= (-0.11,0.24,-0.52)+/-(0.14,0.10,0.16) mas/yr. The stellar proper motions in RA have then be corrected by applying the correction ω_z = -0.52 mas/yr. We show that, apart from their involvement in the general Galactic rotation described by the Oort constants A= 15.82+/-0.21 km/s/kpc and B=-10.87+/-0.15 km/s/kpc, the RGC stars have kinematic peculiarities in the Galactic yz plane related to the kinematics of the warped stellar-gaseous Galactic disk. We show that the parameters of the linear Ogorodnikov-Milne model that describe the kinematics of RGC stars in the zx plane do not differ significantly from zero. The situation in the yz plane is different. For example, the component of the solid-body rotation vector of the local solar neighborhood around the Galactic x axis is M_32- = -2.6+/-0.2 km/s/kpc. Two parameters of the deformation tensor in this plane, namely M_23^+ = 1.0+/-0.2 km/s/kpc and (M_33-M_22)= -1.3+/-0.4 km/s/kpc, also differ significantly from zero. On the whole, the kinematics of the warped stellar-gaseous Galactic disk in the local solar neighborhood can be described as a rotation around the Galactic X axis (close to the line of nodes of this structure) with an angular velocity (-3.1+/-0.5) < Ω_W < (-4.4+/-0.5) km/s/kpc.

arXiv comment17 pages, 3 tables, 2 figures

References in corpus (10)

• The second US Naval Observatory CCD Astrograph Catalog (UCAC2)
• Three Dimensional Structure of the Milky Way Disk
• The Distribution of Nearby Stars in Velocity Space Inferred from Hipparcos Data
• Outer structure of the Galactic warp and flare: explaining the Canis Major over-density
• The Y^2 Stellar Evolutionary Tracks
• Global properties of the HI distribution in the outer Milky Way
• Generation of galactic disc warps due to intergalactic accretion flows onto the disc
• Evidence for coupling between the Sagittarius dwarf galaxy and the Milky Way warp
• The high-velocity clouds and the Magellanic Clouds
• VLA+PT Astrometry of 46 Radio Stars

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• The kinematic signature of the Galactic warp in Gaia DR1 - I. The Hipparcos subsample
• Characterizing the Galactic warp with Gaia: I. The tilted ring model with a twist
• Cepheid Kinematics and the Galactic Warp
• Kinematic Properties of Open Star Clusters with Data from the Gaia DR2 Catalogue
• Three-Dimensional Kinematics of Classical Cepheids
• Residual HCRF Rotation relative to the Inertial Coordinate System
• Kinematics of Hot Subdwarfs from the Gaia DR2 Catalogue
• Capture of field stars by giant interstellar clouds: the formation of moving stellar groups