Kinematics of the old stellar population at the Galactic Center

Abstract

We aim at a detailed description of the kinematic properties of the old, (several Gyrs) late-type CO-absorption star population among the Galactic centre (GC) cluster stars. We applied AO-assisted, near-infrared imaging and integral-field spectroscopy using the instruments NAOS/CONICA and SINFONI at the VLT. We obtained proper motions for 5445 stars, 3D velocities for 664 stars, and acceleration limits (in the sky plane) for 750 stars. We detect for the first time significant cluster rotation in the sense of the general Galactic rotation in proper motions. Out of the 3D velocity dispersion, we derive an improved statistical parallax for the GC of R0 = 8.07 +/- 0.32 (stat) +/- 0.13 (sys) kpc. The distribution of 3D stellar speeds can be approximated by local Maxwellian distributions. Kinematic modelling provides deprojected 3D kinematic parameters, including the mass profile of the cluster. We find an upper limit of 4% for the amplitude of fluctuations in the phase-space distribution of the cluster stars compared to a uniform, spherical model cluster. Using upper limits on accelerations, we constrain the minimum line-of-sight distances from the plane of SgrA* of five stars located within the innermost few (projected) arcsec. The stars within 0.7'' radius from the star group IRS13E do not co-move with this group, making it unlikely that IRS13E is the core of a substantial star cluster. Overall, the GC late-type cluster is described well as a uniform, isotropic, rotating, dynamically relaxed, phase-mixed system.

23 pages, 20 figures, accepted by A&A. This versions corresponds to the one to be printed. Some language editing done, one figure in Sect. 5.6 replaced by a table, a few bugs and typos corrected

References in corpus (11)

• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• The structure of the nuclear stellar cluster of the Milky Way
• Ground-Based CCD Astrometry with Wide Field Imagers. I. [Observations just a few years apart allow decontamination of field objects from members in two Globular clusters.]
• NMAGIC: Fast Parallel Implementation of a Chi-Squared-Made-to-Measure Algorithm for Modelling Observational Data
• Ground-based CCD astrometry with wide field imagers. II. A star catalogue for M67: [email protected] MPG/ESO astrometry, FLAMES@VLT radial velocities
• Evidence for a Long-Standing Top-Heavy IMF in the Central Parsec of the Galaxy
• The distance to the Galactic Centre based on Population-II Cepheids and RR Lyrae stars
• Re-visiting the relations: Galactic thin disc age-velocity dispersion relation
• Hypervelocity Stars III. The Space Density and Ejection History of Main Sequence Stars from the Galactic Center
• LMC origin of the hyper-velocity star HE 0437-5439. Beyond the supermassive black hole paradigm
• Low Metallicity Indicates that the Hypervelocity Star HE 0437-5439 was Ejected from the LMC

Cited by in corpus (2)

• Dynamical evolution of the young stars in the Galactic center: N-body simulations of the S-stars
• Study of the Science Capabilities of PRIMA in the Galactic Center