We present the kinematics of a sample of 398 DA white dwarfs from the SPY project (ESO SN Ia Progenitor surveY) and discuss kinematic criteria for distinguishing of thin-disk, thick-disk, and halo populations. This is the largest homogeneous sample of white dwarfs for which 3D space motions have been determined. Since the percentage of old stars among white dwarfs is higher than among main-sequence stars, they are presumably valuable tools in studies of old populations, such as the halo and the thick disk. Studies of white-dwarf kinematics can help to determine the fraction of the total mass of our Galaxy contained in the form of thick-disk and halo white dwarfs, an issue which is still under discussion. Radial velocities and spectroscopic distances obtained by the SPY project were combined with our measurements of proper motions to derive 3D space motions. Galactic orbits and further kinematic parameters were computed. We calculated individual errors of kinematic parameters by means of a Monte Carlo error propagation code. Our kinematic criteria for assigning population membership were deduced from a sample of F and G stars taken from the literature, for which chemical criteria can be used to distinguish between a thin-disk, a thick-disk and a halo star. Our kinematic population classification scheme is based on the position in the U − V-velocity diagram, the position in the J z -eccentricity diagram, and the Galactic orbit. We combined this with age information and found seven halo and 23 thick-disk white dwarfs in this brightness limited sample. Another four rather cool white dwarfs probably also belong to the thick disk. Correspondingly 2% of the white dwarfs belong to the halo and 7% to the thick disk. The mass contribution of the thick-disk white dwarfs is found to be substantial, but is insufficient to account for the missing dark matter.

Abstract.We have started a large survey for radial velocity variations in white dwarfs (PI R. Napiwotzki) with the aim of finding close double degenerates, which could be precursor systems for SNe Ia. The UVES spectrograph at the ESO VLT is used to obtain high resolution spectra with good S/N. During this project 1500 white dwarfs will be observed. This unique data set will also allow to derive atmospheric parameters and masses for the largest sample of white dwarfs ever analyzed in a homogenous way. In this paper we present a catalog of objects and report results for the first sample of about 200 white dwarfs, many of which are spectroscopic confirmations of candidates from the HE, MCT, and EC surveys. Among the peculiar spectra we identify two new magnetic DA, one previously known magnetic DA, several DA with emission cores, in some cases due to a late-type companion, and two new DBA.

We have started a large survey for double degenerate (DD) binaries as potential progenitors of type Ia supernovae with the UVES spectrograph at the ESO VLT (ESO SN Ia Progenitor surveY -SPY). About 400 white dwarfs were checked for radial velocity variations during the first 15 months of this project, twice the number of white dwarfs investigated during the last 20 years. We give an overview of the SPY project and present first results Fifty four new DDs have been discovered, seven of them double lined (only 18 and 6 objects of these groups were known before, respectively). The final sample is expected to contain 150 to 200 DDs. Eight new pre-cataclysmic binaries were also detected. SPY is the first DD survey which encompasses also non-DA white dwarfs. SPY produces an immense, unique sample of very high resolution white dwarf spectra, which provides a lot of spin-off opportunities. We describe our projects to exploit the SPY sample for the determination of basic parameters, kinematics, and rotational velocities of white dwarfs. A catalogue with a first subset of our white dwarf data has already been published by Koester et al. (2001).

Abstract. In the course of our search for double degenerate binaries as potential progenitors of type Ia supernovae with the UVES spectrograph at the ESO VLT (ESO SN Ia Progenitor surveY -SPY) we discovered that the sdB star HE 1047−0436 is radial velocity variable. The orbital period of 1.213253 d, a semi-amplitude of 94 km s −1 , and a minimum mass of the invisible companion of 0.44 M are derived from the analysis of the radial velocity curve. We use an upper limit on the projected rotational velocity of the sdB star to constrain the system inclination and the companion mass to M > 0.71 M , bringing the total mass of the system closer to the Chandrasekhar limit. However, the system will merge due to loss of angular momentum via gravitational wave radiation only after several Hubble times. Atmospheric parameters and metal abundances are also derived. The resulting values are typical for sdB stars.

Abstract. We present kinematics of a sample of 107 DA white dwarfs from the SPY project (ESO SN Ia Progenitor surveY) and discuss kinematic criteria for a distinction of thin disk, thick disk, and halo populations. This is the first homogeneous sample of white dwarfs for which 3D space motions have been determined. Since the percentage of old stars among white dwarfs is higher than among main-sequence stars, they are presumably valuable tools in studies of old populations such as the halo and the thick disk. Studies of white dwarf kinematics can help to determine the fraction of the total mass of our Galaxy contained in the form of thick disk and halo white dwarfs, an issue which is still under discussion. Radial velocities and spectroscopic distances obtained by the SPY project are combined with our measurements of proper motions to derive 3D space motions. Galactic orbits and further kinematic parameters are computed. We calculate individual errors of kinematic parameters by means of a Monte Carlo error propagation code. Our kinematic criteria for assigning population membership are deduced from a sample of F and G stars taken from the literature for which chemical criteria can be used to distinguish between thin disk, thick disk and halo. Candidates for thick disk and halo members are selected in a first step from the classical U-V-velocity diagram. Our final assignment of population membership is based on orbits and position in the J z -eccentricity diagram. We find four halo and twelve thick disk white dwarfs. We also present a systematic study of the effects of ignoring the radial velocity in kinematic investigations.