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 (DD) 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 white dwarf HE 1414−0848 is a double-lined DA+DA binary with an orbital period of P = 12 h 25 m 39 s . Semi-amplitudes of 128 km s −1 and 100 km s −1 are derived for the individual components. The amplitude ratio and the measured difference in gravitational redshift is used to estimate the masses of the individual components: 0.55 M and 0.71 M . Hence the total mass of the HE 1414−0848 system is 1.26 M , only 10% below the Chandrasekhar limit. The results of a model atmosphere analysis are consistent with our mass estimated from the orbit. Temperatures of the individual components are also determined. Possible scenarios for the formation of this system are discussed. The system will merge due to loss of angular momentum via gravitational wave radiation after two Hubble times. HE 1414−0848 does not qualify as an SN Ia progenitor, but it is the most massive close DD known today.

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 report the discovery of an eclipsing binary -HS 0705+6700 -being an sdB star with a faint companion. From its light curve the orbital period of 8263.87 s, the mass ratio of the system q = 0.28, the inclination of 84.• 4 and other system parameters are derived. The companion does not contribute to the optical light of the system except through a strong reflection effect. The semi-amplitude of the radial velocity curve K1 = 85.8 km s −1 and a mass function of f (m) = 0.00626 M are determined. A spectroscopic analysis of the blue spectra results in T eff = 28 800 K, log g = 5.40, and log(nHe/nH) = −2.68. These characteristics are typical for sdB stars, as is its mass of 0.48 M . According to its mass (0.13 M ) and radius (0.19 R ), the companion is an M dwarf. The primary is in a core helium burning phase of evolution, and the system must have gone through a common envelope stage when the primary was near the tip of the red giant branch.