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Six New ZZ Ceti Stars from the SPY and the HQS Surveys
(Astronomical Society of the Pacific, 2007)
We report on the discovery of six new ZZCeti stars. They were selected as candidates based on preparatory photometric observations of ob- jects from the Hamburg Quasar Survey (HQS), and based on the spectra of the Supernova ...
Discovery of the First Very Wide WD LD Binary System
(Astronomical Society of the Pacific, 2007)
We report on our large scale search of 2MASS and SuperCOS- MOS in the southern hemisphere for very widely separated white dwarf / L-dwarf binary systems and present our findings, including eight widely separated can- didate ...
An object that defies stereotypes : X-ray observations of SBS 1150+599A - the binary nucleus of PN G135.9+55.9
(2007)
We present X-ray observations of the close binary nucleus of the planetary nebula (PN) PN G135.9+55.9 obtained with the XMM satellite. The nebula is the most oxygen-poor PN known to date and is located in the Galactic halo. ...
Binary White Dwarfs in the Supernova Ia Progenitor Survey
(Astronomical Society of the Pacific, 2007)
We report results of a systematic radial velocity survey for double degenerate (DD) binaries as potential progenitors of type Ia supernovae: SPY (ESO Supernovae Ia Progenitor surveY). More than 1000 white dwarfs (WDs) and ...
White Dwarfs in the European Galactic Plane Surveys (EGAPS)
(Astronomical Society of the Pacific, 2007)
The space density of white dwarfs is highly uncertain even nearby. This results from the fact that the known sample of white dwarfs is largely in- complete in part because most white dwarfs have been discovered as by-products ...
3D-Kinematics of White Dwarfs from the SPY-Project
(Astronomical Society of the Pacific, 2007)
We present a progress report on the kinematical analysis of the entire SPY (ESO SN Ia Progenitor surveY; see Napiwotzki et al. 2001) sample of about one thousand white dwarfs and hot subdwarfs. In a previous study (Pauli ...
Testing Magnetic Braking: The X-ray Activity of M Dwarfs in Pre-Cataclysmic Variable Systems
(Astronomical Society of the Pacific, 2007)
Angular momentum loss by magnetic braking is believed to be an important mechanism in the evolution of tidally-locked white dwarf (WD) bina- ries. We measure the X-ray emission of a sample of M dwarfs in pre-cataclysmic ...
The Subdwarf B + White Dwarf Binary KPD 1930+2752, a Supernova Type Ia Progenitor Candidate
(Astronomical Society of the Pacific, 2007)
The nature of the progenitors of type Ia supernovae is still under controversial debate. KPD 1930+2752 is one of the best SN Ia progenitor can- didates known today. The object is a double degenerate system consisting of a ...
The Fraction of DA White Dwarfs with Kilo-Gauss Magnetic Fields
(Astronomical Society of the Pacific, 2007)
Current estimates for white dwarfs with fields in excess of 1MG are about 10%; according to our first high-precision circular-polarimetric study of 12 bright white dwarfs with the VLT (Aznar Cuadrado et al. 2004) this ...
The Origins of the Ultramassive White Dwarf GD50
(Astronomical Society of the Pacific, 2007)
On the basis of astrometric and spectroscopic data we argue that the ultramassive white dwarf GD 50 is associated with the star formation event that created the Pleiades and is potentially a former cluster member. Its ...