EDP Sciences
Free access
Volume 480, Number 3, March IV 2008
Page(s) 753 - 765
Section Galactic structure, stellar clusters, and populations
DOI http://dx.doi.org/10.1051/0004-6361:20066948
Published online 17 January 2008

A&A 480, 753-765 (2008)
DOI: 10.1051/0004-6361:20066948

Galactic kinematics with RAVE data

I. The distribution of stars towards the Galactic poles
L. Veltz1, 2, 3, O. Bienaymé1, K. C. Freeman2, J. Binney4, J. Bland-Hawthorn5, B. K. Gibson6, G. Gilmore7, E. K. Grebel8, 9, A. Helmi10, U. Munari11, J. F. Navarro12, Q. A. Parker13, 14, G. M. Seabroke7, A. Siebert1, 3, M. Steinmetz3, F. G. Watson13, M. Williams2, 3, R. F. G. Wyse15, and T. Zwitter16

1  Observatoire Astronomique de Strasbourg, Strasbourg, France
    e-mail: veltz@astro.u-strasbg.fr
2  RSAA, Mount Stromlo Observatory, Canberra, Australia
3  Astrophysikalisches Institut Potsdam, Potsdam, Germany
4  Rudolf Peierls Centre for Theoretical Physics, University of Oxford, UK
5  School of Physics, University of Sydney, Australia
6  University of Central Lancashire, Preston, UK
7  Institute of Astronomy, University of Cambridge, UK
8  Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Heidelberg, Germany
9  Astronomical Institute of the University of Basel, Basel, Switzerland
10  Kapteyn Astronomical Institute, University of Groningen, Groningen, The Netherlands
11  INAF Osservatorio Astronomico di Padova, Asiago, Italy
12  University of Victoria, Victoria, Canada
13  Anglo Australian Observatory, Sydney, Australia
14  Macquarie University, Sydney, Australia
15  Johns Hopkins University, Baltimore MD, USA
16  University of Ljubljana, Department of Physics, Ljubljana, Slovenia

(Received 15 December 2006 / Accepted 18 December 2007)

We analyze the distribution of G and K type stars towards the Galactic poles using RAVE and ELODIE radial velocities, 2MASS photometric star counts, and UCAC2 proper motions. The combination of photometric and 3D kinematic data allows us to disentangle and describe the vertical distribution of dwarfs, sub-giants and giants and their kinematics.

We identify discontinuities within the kinematics and magnitude counts that separate the thin disk, thick disk and a hotter component. The respective scale heights of the thin disk and thick disk are 225 $\pm$ 10 pc and 1048 $\pm$ 36 pc. We also constrain the luminosity function and the kinematic distribution function. The existence of a kinematic gap between the thin and thick disks is incompatible with the thick disk having formed from the thin disk by a continuous process, such as scattering of stars by spiral arms or molecular clouds. Other mechanisms of formation of the thick disk such as "created on the spot" or smoothly "accreted" remain compatible with our findings.

Key words: stars: kinematics -- Galaxy: disk -- Galaxy: fundamental parameters -- Galaxy: kinematics and dynamics -- Galaxy: structure

© ESO 2008