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Browsing by Author "Heber, U."
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3D kinematics of white dwarfs from the SPY project
Pauli, E.M.; Napiwotzki, R.; Altmann, M.; Heber, U.; Odenkirchen, M.; Kerber, F. (2003-03)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 ... -
3D kinematics of white dwarfs from the SPY project. II
Pauli, E.M.; Napiwotzki, R.; Heber, U.; Altmann, M.; Odenkirchen, M. (2006) -
3D-Kinematics of White Dwarfs from the SPY-Project
Richter, R.; Heber, U.; Napiwotzki, R. (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 ... -
Abundances of UV bright stars in globular clusters. I. ROA 5701 in omega Centauri and Barnard 29 in M 13
Moehler, S.; Heber, U.; Lemke, M.; Napiwotzki, R. (1998)Two UV brights stars in globular clusters, ROA 5701 (ω Cen) and Barnard 29 (M 13) are analysed from high-resolution UV and optical spectra. The main aim is the measurement of iron abundances from UV spectra obtained with ... -
The B-type giant HD 271791 in the Galactic halo : Linking run-away stars to hyper-velocity stars
Heber, U.; Edelmann, H.; Napiwotzki, R.; Altmann, M.; Scholz, R.D. (2008-05-01)Context. Young, massive stars have been found in the distant Galactic halo. Dynamical ejection from the Galactic disc has been suggested as the origin of these "run-away stars". The so-called hyper-velocity stars have been ... -
Binaries discovered by the MUCHFUSS project SDSS J08205+0008 - An eclipsing subdwarf B binary with brown dwarf companion
Geier, S.; Schaffenroth, V.; Drechsel, H.; Heber, U.; Kupfer, T.; Tillich, A.; Ostensen, R.; Smolders, K.; Degroote, P.; Maxted, P.F.L.; Barlow, B.N.; Gansicke, B.T.; Marsh, T.R.; Napiwotzki, R. (2011)Hot subdwarf B stars (sdBs) are extreme horizontal branch stars believed to originate from close binary evolution. Indeed about half of the known sdB stars are found in close binaries with periods ranging from a few hours ... -
Binaries discovered by the SPY project. I. HE 1047-0436: A subdwarf B white dwarf syste
Napiwotzki, R.; Edelmann, H.; Heber, U.; Karl, C.; Drechsel, H.; Pauli, E.M.; Christlieb, N. (2001-10)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 SNIa Progenitor surveY { SPY) we discovered that the sdB star HE1047−0436 ... -
Binaries discovered by the SPY project. III. HE 2209-1444: A massive, short period double degenerate
Karl, C.; Napiwotzki, R.; Nelemans, G.; Christlieb, N.; Koester, D.; Heber, U.; Reimers, D. (2003-11)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 HE2209−1444 to be ... -
Binaries discovered by the SPY project: V. GD 687 – a massive double degenerate binary progenitor that will merge within a Hubble time
Geier, S.; Heber, U.; Kupfer, T.; Napiwotzki, R. (2010)The ESO SN Ia Progenitor Survey (SPY) aims at finding merging double degenerate binaries as candidates for supernova type Ia (SN Ia) explosions. A white dwarf merger has also been suggested to explain the formation of rare ... -
Binaries discovered by the SPY survey VI : Discovery of a low mass companion to the hot subluminous planetary nebula central star EGB5-a recently ejected common envelope?
Geier, S.; Napiwotzki, R.; Heber, U.; Nelemans, G. (2011)Hot subdwarf B stars (sdBs) in close binary systems are assumed to be formed via common envelope ejection. According to theoretical models, the amount of energy and angular momentum deposited in the common envelope scales ... -
Binary sdB Stars with Massive Compact Companions
Geier, S.; Karl, C.; Edelmann, H.; Heber, U.; Napiwotzki, R. (Astronomical Society of the Pacific, 2008)The masses of compact objects like white dwarfs, neutron stars and black holes are fundamental to astrophysics, but very difficult to measure. We present the results of an analysis of subluminous B (sdB) stars in close ... -
Binary White Dwarfs in the Supernova Ia Progenitor Survey
Napiwotzki, R.; Karl, C.; Nelemans, G.; Yungelson, L.; Christlieb, N.; Drechsel, H.; Heber, U.; Homeier, D.; Koester, D.; Leibundgut, B.; Marsh, T.R.; Moehler, S.; Renzini, A.; Reimers, D. (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 ... -
Close binary EHB stars from SPY
Napiwotzki, R.; Karl, C.; Lisker, T.; Heber, U.; Christlieb, N.; Reimers, D.; Nelemans, G.; Homeier, D. (2004-06) -
Discovery of a helium-core white dwarf progenitor
Heber, U.; Edelmann, H.; Lisker, T.; Napiwotzki, R. (2003-12) -
Double Degenerate and Progenitors of Supernovae Type Ia
Napiwotzki, R.; Yungelson, L.; Nelemans, G.; Marsh, T.R.; Leibundgut, B.; Renzini, A.; Homeier, D.; Koester, D.; Moehler, S.; Christlieb, N.; Reimers, D.; Drechsel, H.; Heber, U.; Karl, C.; Pauli, E.M. (Astronomical Society of the Pacific, 2004)We report on systematic radial velocity surveys for white dwarf { white dwarf binaries (double degenerates { DDs) including SPY (ESO Supernovae Ia progenitor survey) recently carried out at the VLT. A large sample of DD ... -
The ESO supernovae type Ia progenitor survey (SPY) : The radial velocities of 644 DA white dwarfs
Napiwotzki, R.; Karl, C. A.; Lisker, T.; Catalan, S.; Drechsel, H.; Heber, U.; Homeier, D.; Koester, D.; Leibundgut, B.; Marsh, T. R.; Moehler, S.; Nelemans, G.; Reimers, D.; Renzini, A.; Stroer, A.; Yungelson, L. (2019-07-27)Close double degenerate binaries are one of the favoured progenitor channels for type Ia supernovae, but it is unclear how many suitable systems there are in the Galaxy. We report results of a large radial velocity survey ... -
First VLT spectra of white dwarfs in a globular cluster
Moehler, S.; Heber, U.; Napiwotzki, R.; Koester, D.; Renzini, A. (2000)We present the first spectra obtained with the Very Large Telescope for white dwarfs in a globular cluster. Estimates of atmospheric parameters are obtained and compared to evolutionary tracks. We discuss possible implications ... -
FUSE Observations of EC14026 Stars
Chayer, P.; Fontaine, G.; Fontaine, M.; Lamontagne, R.; Wesemael, F.; Dupuis, J.; Heber, U.; Napiwotzki, R.; Moehler, S. (2004)We present a FUSE abundance analysis of EC14026 stars. We compare the abundances of heavy elements in the atmospheres of EC14026 stars to non-pulsating stars with similar atmospheric parameters, and investigate whether ... -
HE 0437-5439: an unbound hypervelocity main-sequence B-type star
Edelmann, H.; Napiwotzki, R.; Heber, U.; Christlieb, N.; Reimers, D. (2005) -
High resolution UVES/VLT spectra of white dwarfs observed for the ESO SN Ia Progenitor Survey III. DA white dwarfs
Koester, D.; Voss, B.; Napiwotzki, R.; Christlieb, N.; Homeier, D.; Lisker, T.; Reimers, D.; Heber, U. (2009-10)Context. The ESO Supernova Ia Progenitor Survey (SPY) took high-resolution spectra of more than 1000 white dwarfs and pre-white dwarfs. About two thirds of the stars observed are hydrogen-dominated DA white dwarfs. Here ...