A survey for post common-envelope binary stars using GALEX and SDSS photometry (2009)
Maxted, P. F. L., Gaensicke, B. T., Burleigh, M. R., Southworth, J., Marsh, T. R., Napiwotzki, R., ...
We report the first results of our programme to obtain multi-epoch radial velocity measurements of stars with a strong far-UV excess to identify post common-envelope binaries (PCEBs). The targets...
Koester, D., Voss, B., Napiwotzki, R., Christlieb, N., Homeier, D., Lisker, T., ...
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...
The UV-Excess Survey of the Northern Galactic Plane (UVEX) (2009)
Groot, Paul J., Verbeek, K., Greimel, R., Irwin, M., Gonzalez-Solares, E., Gaensicke, B., ...
The UV-Excess Survey of the Northern Galactic Plane images a 10x185 degree wide band, centered on the Galactic Equator using the 2.5m Isaac Newton Telescope in four bands (U,g,r,HeI5875) down to...
A new detailed examination of white dwarfs in NGC3532 and NGC2287 (2009)
Dobbie, P. D., Napiwotzki, R., Burleigh, M. R., Williams, K., Sharp, R. G., Barstow, M. A., ...
We present the results of a photometric and spectroscopic study of the white dwarf candidate members of the intermediate age open clusters NGC3532 and NGC2287. Of the nine objects investigated, it is...
The astrophysics of ultra-compact binaries (2009)
Nelemans, G., Wood, M., Groot, P., Anderson, S., Belczynski, K., Benacquista, M., ...
This white paper briefly describes the astrophysics of ultra-compact binaries, with emphasis of the challenges and opportunities in the next decade.
High resolution optical spectroscopy of Praesepe white dwarfs (2009)
Casewell, S. L., Dobbie, P. D., Napiwotzki, R., Burleigh, M. R., Barstow, M. A., Jameson, R. F.
We present the results of a high resolution optical spectroscopic study of nine white dwarf candidate members of Praesepe undertaken with the VLT and UVES. We find, contrary to a number of previous...
Central Stars of Planetary Nebulae in IPHAS and SDSS (2009)
Weston, S., Napiwotzki, R., Sale, S.
Space densities and birthrates of Planetary Nebulae (PNe) are highly uncertain. A large range of formation rates has been derived by different studies, which has led to contradicting ideas for the...
The Age of White Dwarf Companions (2009)
We carried out a spectroscopic investigation of single lined white dwarfs (WDs) in double degenerate (DD) systems and discuss their binary evolution. Simulated spectra of the Halpha region are used...
High spatial resolution Galactic 3D extinction mapping with IPHAS. (2009)
Sale, S.E., Drew, J.E., Unruh, Y.C., Irwin, M.J., Knigge, C., Phillips, S., ...
‘The definitive version is available at www3.interscience.wiley.com '. Copyright Blackwell Publishing / Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2008.14083.x
Koester, D., Voss, B., Napiwotzki, R., Christlieb, N., Homeier, D., Lisker, T., ...
Original article can be found at: http://www.aanda.org/ Copyright The European Southern Observatory (ESO) DOI: 10.1051/0004-6361/200912531
High Spatial Resolution Galactic 3D Extinction Mapping with IPHAS (2008)
Sale, S. E., Drew, J. E., Unruh, Y. C., Irwin, M. J., Knigge, C., Phillipps, S., ...
We present an algorithm ({\scshape mead}, for `Mapping Extinction Against Distance') which will determine intrinsic ($r' - i'$) colour, extinction, and distance for early-A to K4 stars extracted from...
A planetary nebula around nova V458 Vul undergoing flash ionization (2008)
Wesson, R., Barlow, M. J., Corradi, R. L. M., Drew, J. E., Groot, P. J., Knigge, C., ...
Nova V458 Vul erupted on 2007 August 8th and reached a visual magnitude of 8.1 a few days later. H$\alpha$ images obtained six weeks before the outburst as part of the IPHAS galactic plane survey...
Discovery of a widely separated UCD-WD binary (2008)
Day-Jones, A. C., Pinfield, D. J., Napiwotzki, R., Burningham, B., Jenkins, J. S., Jones, H. R. A., ...
We present the discovery of the widest known ultracool dwarf - white dwarf binary. This binary is the first spectroscopically confirmed widely separated system from our target sample. We have used...
Model Spectra of Hot Subdwarfs for the Gaia Mission (2008)
Hindson, L., Napiwotzki, R., Heber, U., Lemke, M.
The Gaia mission will provide an unprecedented 3D view of our galaxy, it will obtain astrometric, photometric and spectrographic data for roughly one billion stars. We are particularly interested in...
Geier, S., Heber, U., Napiwotzki, R.
We present new results from follow-up time-resolved spectroscopy of radial velocity variable hot subdwarfs from the SPY project. Medium resolution spectra were taken at the ESO NTT. Preliminary...
Binary sdB Stars with Massive Compact Companions (2008)
Geier, S., Karl, C., Edelmann, H., Heber, U., Napiwotzki, R.
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...
Metal Abundances of Subdwarf B Stars from SPY - a Pattern Emerges (2008)
Geier, S., Heber, U., Napiwotzki, R.
The formation of sdBs is still puzzling, as is the chemical composition of their atmospheres. While helium and other light elements are depleted relative to solar values, heavy elements are highly...
Przybilla, N., Nieva, M. F., Heber, U., Firnstein, M., Butler, K., Napiwotzki, R., ...
Context: Hyper-velocity stars move so fast that only a supermassive black hole (SMBH) seems to be capable to accelerate them. Hence the Galactic centre (GC) is their only suggested place of origin....
Recycling Matter in the Universe. X-ray observations of SBS 1150+599A (PN G135.9+55.9). (2008)
Tovmassian, G.H., Tomsick, J., Napiwotzki, R., Yungelson, L., Pena, M., Stasińska, G, ...
Original paper can be found at: http://proceedings.aip.org/proceedings/ Copyright AIP DOI: 10.1063/1.2840455
The Origin of Helium-Rich Subdwarf O Stars. (2008)
Original paper can be found at: http://www.astrosociety.org/pubs/cs/381.html Copyright ASP
Przybilla, N., Nieva, M.A., Heber, U., Firnstein, M., Butler, K., Napiwotzki, R., ...
Original article can be found at: http://www.aanda.org/ Copyright The European Southern Observatory DOI: 10.1051/0004-6361:200809391
Geier, S., Heber, U., Napiwotzki, R.
Original paper can be found at: http://astrosociety.org/pubs/cs/381.html Copyright ASP
Binary sdB Stars with Massive Compact Companions. (2008)
Geier, S., Karl, C., Edelmann, H., Heber, U., Napiwotzki, R.
Original paper can be found at: http://astrosociety.org/pubs/cs/381.html Copyright ASP
Metal Abundances of Subdwarf B Stars from SPY - a Pattern Emerges. (2008)
Geier, S., Heber, U., Napiwotzki, R.
Original paper can be found at: http://astrosociety.org/pubs/cs/381.html Copyright ASP
Model Spectra of Hot Subdwarfs for the Gaia Mission. (2008)
Hindson, L., Napiwotzki, R., Heber, U., Lemke, M.
Original paper can be found at: http://astrosociety.org/pubs/cs/381.html Copyright ASP
Hypervelocity Stars: Young and Heavy or Old and Light? (2008)
Heber, U., Hirsch, H., Edelmann, H., Napiwotzki, R., O'Toole, S., Brown, W., ...
Original paper can be found at: http://astrosociety.org/pubs/cs/381.html Copyright ASP
Discovery of a widely separated ultracool dwarf–white dwarf binary. (2008)
Day-Jones, A.C., Pinfield, D.J., Napiwotzki, R., Burningham, B., Jenkins, J.S., Jones, H.R.A., ...
‘The definitive version is available at www.blackwell-synergy.com.’ Copyright Blackwell Publishing DOI: 10.1111/j.1365-2966.2008.13455.x
A planetary nebula around Nova V458 Vulpeculae undergoing flash ionization. (2008)
Wesson, R., Barlow, M.J., Corradi, R.L.M., Drew, J.E., Groot, P., Knigge, C., ...
Original article can be found at: http://www.iop.org/EJ/journal/apjl Copyright American Astronomical Society [Full text of this article is not available in the UHRA]
Tovmassian, G., Tomsick, J., Napiwotzki, R., Yungelson, L., Stasińska, G., Peña, M., ...
We present X-ray observations of the close binary nucleus of the planetary nebula 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...
High-Resolution Spectra Observed for SPY. II. DB and DBA Stars (2007)
Voss, B., Koester, D., Napiwotzki, R., Christlieb, N., Reimers, D.
We present a detailed spectroscopic analysis of the stars with helium-dominated spectra in the ESO Supernova Ia Progenitor Survey (SPY). Atmospheric parameters, masses, and abundances of trace...
Six New ZZ Ceti Stars from the SPY and the HQS Surveys (2007)
Voss, B., Koester, D., Østensen, R., Napiwotzki, R., Homeier, D., Reimers, D.
We report on the discovery of six new ZZ Ceti stars. They were selected as candidates based on preparatory photometric observations of objects from the Hamburg Quasar Survey (HQS), and based on the...
A Debris Disk around the Central Star of the Helix Nebula? (2007)
Su, Kate Y. L., Rieke, G. H., Huggins, P. J., Gruendl, R., Napiwotzki, R., ...
Excess emission from a point-like source coincident with the central star of the Helix Nebula is detected with Spitzer at 8, 24, and 70 um. At 24 um, the central source is superposed on an extended...
The mass and radius of the M-dwarf in the short period eclipsing binary RR Caeli (2007)
Maxted, P. F. L., O'Donoghue, D., Morales-Rueda, L., Napiwotzki, R.
We present new photometry and spectroscopy of the eclipsing white dwarf - M-dwarf binary star RR Cae. We use timings of the primary eclipse from white-light photo-electric photometry to derive a new...
Discovery of the First Very Wide WD LD Binary System (2007)
Day-Jones, A.C., Pinfield, D.J., Jones, H.R.A., Kendall, T.R., Napiwotzki, R., Jenkins, J.S.
The fraction of DA white dwarfs with kilo-Gauss magnetic fields (2007)
Jordan, S., Aznar Cuadrado, R., Napiwotzki, R., Schmid, H. M., Solanki, S. K.
The fraction of DA White Dwarfs with kilo-Gauss magnetic fields (2007)
Jordan, S., Aznar Cuadrado, R., Napiwotzki, R., Schmid, H. M., Solanki, S. K.
The Origins of the Ultramassive White Dwarf GD50. (2007)
Dobbie, P.D., Napiwotzki, R., Lodieu, N., Burleigh, M.R., Barstow, M.A., Jameson, R.F.
The Fraction of DA White Dwarfs with Kilo-Gauss Magnetic Fields. (2007)
Jordan, S., Aznar Cuadrado, R., Napiwotzki, R., Schmid, H.M., Solanki, S.K.
Binary White Dwarfs in the Supernova Ia Progenitor Survey. (2007)
Napiwotzki, R., Karl, C., Nelemans, G., Yungelson, L., Christlieb, N., Drechsel, H., ...
The Subdwarf B + White Dwarf Binary KPD 1930+2752, a Supernova Type Ia Progenitor Candidate. (2007)
Geier, S., Nesslinger, S., Heber, U., Przybilla, N., Napiwotzki, R.
Spectroscopic Analysis of Subluminous B Stars in Binaries with Compact Companions. (2007)
Geier, S., Karl, C., Edelmann, H., Heber, U., Napiwotzki, R.
Follow-up Observations of SPY White Dwarf + M-Dwarf Binaries. (2007)
Maxted, P.F.L., Napiwotzki, R., Marsh, T.R., Burleigh, M.R., Dobbie, P.D., Hogan, E., ...
Testing Magnetic Braking: The X-ray Activity of M Dwarfs in Pre-Cataclysmic Variable Systems. (2007)
Briggs, K.R., Napiwotzki, R., Maxted, P.F.L., Wheatley, P.J.
Six New ZZ Ceti Stars from the SPY and the HQS Surveys. (2007)
Voss, B., Koester, D., Ostensen, R., Napiwotzki, R., Homeier, D., Reimers, D.
A debris disk around the central star of the Helix Nebula? (2007)
Su, K.Y.L., Chu, Y-H., Rieke, G., Huggins, P.J., Gruendl, R., Napiwotzki, R., ...
Original article can be found at: http://www.iop.org/EJ/journal/apjl Copyright American Astronomical Society DOI: 10.1086/513018 [Full text of this article is not available in the UHRA]
3D-Kinematics of White Dwarfs from the SPY-Project (2006)
Richter, R., Heber, U., Napiwotzki, R.
We present a progress report on the kinematical analysis of the entire SPY (ESO SN Ia Progenitor surveY) sample of about one thousand white dwarfs and hot subdwarfs. In a previous study (Pauli et al....
The subdwarf B + white dwarf binary KPD 1930+2752 - a Supernova Type Ia progenitor candidate (2006)
Geier, S., Nesslinger, S., Heber, U., Przybilla, N., Napiwotzki, R.
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 candidates known today. The object is a double degenerate...
Spectroscopic Analysis of subluminous B Stars in Binaries with compact Companions (2006)
Geier, S., Karl, C., Edelmann, H., Heber, U., Napiwotzki, R.
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...
The fraction of DA white dwarfs with kilo-Gauss magnetic fields (2006)
Jordan, S., Cuadrado, R. Aznar, Napiwotzki, R., Schmid, H. M., Solanki, S. K.
Weak magnetic field has been searched for on only a small number of white dwarfs. Current estimates for white dwarfs with fields in excess of 1MG are about 10%; according to previous studies this...
The fraction of DA white dwarfs with kilo-Gauss magnetic fields (2006)
Jordan, S., Cuadrado, R. Aznar, Napiwotzki, R., Schmid, H. M., Solanki, S. K.
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...
White dwarfs in the European Galactic Plane Surveys (EGAPS) (2006)
Morales-Rueda, L., Groot, P. J., Napiwotzki, R., Drew, J., Collaboration, The EGAPS
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 incomplete in part because most white dwarfs have been...
Geier, S., Karl, C., Edelmann, H., Heber, U., Napiwotzki, R.
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...
Recent observational progress in AM CVn binaries (2006)
Ramsay, G., Brocksopp, C., Groot, P., Hakala, P., Lehto, H., Marsh, T., ...
We present the results of some recent research on AM CVn systems. We present: X-ray/UV observations made using XMM-Newton; the X-ray grating spectrum of RX J1914+24; preliminary results of a search...
Geier, S., Nesslinger, S., Heber, U., Przybilla, N., Napiwotzki, R.
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 candidates known today. The object is a double degenerate...
Stroeer, A., Heber, U., Lisker, T., Napiwotzki, R., Dreizler, S., Christlieb, N., ...
We address the origin and evolutionary status of hot subdwarf stars by studying the optical spectral properties of 58 subdwarf O (sdO) stars. Combining them with the results of our previously studied...
Burleigh, M. R., Hogan, E., Dobbie, P. D., Napiwotzki, R., Maxted, P. F. L.
We present a near-infrared spectrum of the close, detached white dwarf + brown dwarf binary WD0137-349 (Maxted et al 2006), that directly reveals the substellar companion through an excess of flux...
On the origin of the ultramassive white dwarf GD50 (2006)
Dobbie, P. D., Napiwotzki, R., Lodieu, N., Burleigh, M. R., Barstow, M. A., Jameson, R. F.
We argue on the basis of astrometric and spectroscopic data that the ultramassive white dwarf GD50 is associated with the star formation event that created the Pleiades and is possibly a former...
Survival of a brown dwarf after engulfment by a red giant star (2006)
Maxted, P. F. L., Napiwotzki, R., Dobbie, P. D., Burleigh, M. R.
(Summary of paper) High resolution optical spectroscopy of the white dwarf WD0137-349 reveals a weak Halpha line in emission, due to a low mass companion in a close orbit. Using this emission...
New Praesepe white dwarfs and the initial mass-final mass relation (2006)
Dobbie, P.D., Napiwotzki, R., Burleigh, Matthew R., Barstow, Martin A., Boyce, D.D., Casewell, S.L., ...
This is the preprint from arxiv.org of a paper subsequently published in the Monthly Notices of the Royal Astronomical Society and available from...
O'Toole, S. J., Napiwotzki, R., Heber, U., Drechsel, H., Frandsen, S., Grundahl, F., ...
The variable sdB known as V46 in the globular cluster M4 has remained enigmatic since its discovery almost 10 years ago. We present here radial velocity measurements obtained from medium-resolution...
New Praesepe white dwarfs and the initial mass-final mass relation (2006)
Dobbie, P. D., Napiwotzki, R., Burleigh, M. R., Barstow, M. A., Boyce, D. D., Casewell, S. L., ...
We report the spectroscopic confirmation of four further white dwarf members of Praesepe. This brings the total number of confirmed white dwarf members to eleven making this the second largest...
On the origin of the ultramassive white dwarf GD50 (2006)
Dobbie, P.D., Napiwotzki, R., Lodieu, N., Burleigh, Matthew R., Barstow, Martin A., Jameson, Richard F.
Accepted for publication in Monthly Notices of the Royal Astronomical Society
Survival of a brown dwarf after engulfment by a red giant star (2006)
Maxted, P.F.L., Napiwotzki, R., Dobbie, P.D., Burleigh, Matthew R.
On the origin of the ultramassive white dwarf GD 50. (2006)
Dobbie, P.D., Napiwotzki, R., Lodieu, N., Burleigh, M.R., Barstow, M.A., Jameson, R.F.
Survival of a brown dwarf after engulfment by a red giant star. (2006)
Maxted, P.F.L., Napiwotzki, R., Dobbie, P.D., Burleigh, M.R.
3D kinematics of white dwarfs from the SPY project. II. (2006)
Pauli, E.M., Napiwotzki, R., Heber, U., Altmann, M., Odenkirchen, M.
Time-resolved observations of the short period CV SDSS J123813.73-033933.0. (2006)
Zharikov, S.V., Tovmassian, G.H., Napiwotzki, R., Michel, R., Neustroev, V.
Discovery of eleven new ZZ Ceti stars. (2006)
Castanheira, B.G., Kepler, S.O., Mullally, F., Winget, D.E., Koester, D., Voss, B., ...
New Praesepe white dwarfs and the initial mass final mass relation. (2006)
Dobbie, P.D., Napiwotzki, R., Burleigh, M.R., Barstow, M.A., Boyce, D.D., Casewell, S.L., ...
Discovery of seven ZZ Ceti stars using a new photometric selection method. (2006)
Voss, B., Koester, D., Ostensen, R., Kepler, S.O., Napiwotzki, R., Homeier, D., ...
The fraction of DA white dwarfs with kilo-Gauss magnetic fields (2006)
Jordan, S., Aznar Cuadrado, R., Napiwotzki, R., Schmid, H. M., Solanki, S. K.
Spectroscopic Analysis of sdB Binaries from the SPY Project (2005)
Karl, C., Heber, U., Napiwotzki, R., Geier, S.
In the course of our search for double degenerate binaries as potential progenitors of type Ia supernovae with the ESO VLT (ESO SN Ia Progenitor SurveY SPY) several new subdwarf B (sdB) binaries with...
Time-resolved observations of the short period CV SDSS J123813.73-033933.0 (2005)
Zharikov, S. V., Tovmassian, G. H., Napiwotzki, R., Michel, R., Neustroev, V.
We observed a new and poorly studied cataclysmic variable (CV) SDSS J123813.73-033933.0 to determine its classification and binary parameters. Simultaneous time-resolved photometric and spectroscopic...
Discovery of eleven new ZZ Ceti stars (2005)
Castanheira, B. G., Kepler, S. O., Mullally, F., Winget, D. E., Koester, D., Voss, B., ...
We report the discovery of eleven new ZZ Cetis using telescopes at OPD (Observat\'orio do Pico dos Dias/LNA) in Brazil, the 4.1 m SOAR (Southern Astrophysical Research) telescope at Cerro Pachon,...
3D kinematics of white dwarfs from the SPY project II (2005)
Napiwotzki, R., Heber, U., Altmann, M., Odenkirchen, M.
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 thin-disk, thick-disk, and halo...
On the most metal-poor PN and its binary central star (2005)
Napiwotzki, R., Tovmassian, G., Richer, M. G., Stasinska, G., Pena, M., Drechsel, H., ...
PN G135.9+55.9 is the most metal-poor PN known in our Galaxy. The central star resides in a short-period binary system with a compact component, probably a white dwarf. We describe new observations,...
Rotation velocities of white dwarfs determined from the CaII K line (2005)
Berger, L., Koester, D., Napiwotzki, R., Reid, I. N., Zuckerman, B.
We determine projected rotation velocities v sini in DAZ white dwarfs, for the first time using the rotational broadening of the CaII K line. The results confirm previous findings that white dwarfs...
Wolf-Rayet and O Star Runaway Populations from Supernovae (2005)
Dray, L. M., Dale, J. E., Beer, M. E., Napiwotzki, R., King, A. R.
We present numerical simulations of the runaway fractions expected amongst O and Wolf-Rayet star populations resulting from stars ejected from binaries by the supernova of the companion....
HS 0146 1847 - a DAZB white dwarf of very unusual composition (2005)
Koester, D., Napiwotzki, R., Voss, B., Homeier, D., Reimers, D.
Two new ZZ Ceti pulsators from the HS and HE surveys (2005)
Silvotti, R., Voss, B., Bruni, I., Koester, D., Reimers, D., Napiwotzki, R., ...
We report the detection of nonradial g-mode oscillations in the DA white dwarfs HS1039+4112 (B=15.9) and HE1429-0343 (B=15.8) from time-series photometry made at the Loiano 1.5 m telescope. The two...
Binaries discovered by the SPY project. IV. Five single-lined DA double white dwarfs (2005)
Nelemans, G., Napiwotzki, R., Karl, C., Marsh, T. R., Voss, B., Roelofs, G., ...
We present results from our ongoing follow-up observations of double white dwarf binaries detected in the ESO SN Ia Progenitor SurveY (SPY). We discuss our observing strategy and data analysis and...
Rotation velocities of white dwarfs. III. DA stars with convective atmospheres (2005)
Karl, C., Napiwotzki, R., Heber, U., Dreizler, S., Koester, D., Reid, I.N.
Six detached white-dwarf close binaries (2005)
Morales-Rueda, L., Maxted, P.F.L., Nelemans, G., Karl, C., Napiwotzki, R., Moran, C.K.J., ...
Metal traces in white dwarfs of the SPY (ESO Supernova Ia Progenitor Survey) sample (2005)
Koester, D., Rollenhagen, K., Napiwotzki, R., Voss, B., Christlieb, N., Homeier, D., ...
Six detached white-dwarf close binaries (2005)
Morales-Rueda, L., Marsh, T. R., Maxted, P. F. L., Nelemans, G., Karl, C., Napiwotzki, R., ...
We determine the orbits of four double degenerate systems (DDs), composed of two white dwarfs, and of two white dwarf -- M dwarf binaries. The four DDs, WD1022+050, WD1428+373, WD1824+040, and...
Kilo-gauss Magnetic Fields in three DA White Dwarfs (2005)
Cuadrado, R. Aznar, Jordan, S., Napiwotzki, R., Schmid, H. M., Solanki, S. K., Mathys, G.
We have detected longitudinal magnetic fields between 2 and 4kG in three normal DA white dwarfs (WD0446-790, WD1105-048, WD2359$-$434) out of a sample of 12 by using optical spectropolarimetry done...
Metal traces in white dwarfs of the SPY (ESO Supernova Ia Progenitor Survey) sample (2005)
Koester, D., Rollenhagen, K., Napiwotzki, R., Voss, B., Christenlieb, N., Homeier, D., ...
A near-IR spectrum of the DO white dwarf RE J0503-285 (2005)
Dobbie, P.D., Burleigh, Matthew R., Levan, Andrew J., Barstow, Martin A., Napiwotzki, R., Hubeny, I.
The definitive version of this paper is available from www.edpsciences.org/aa
Binaries discovered by the SPY project - IV. Five single-lined DA double white dwarfs (2005)
Nelemans, G., Napiwotzki, R., Karl, C., Marsh, T.R., Voss, B., Roelofs, G., ...
Kilo-Gauss magnetic fields in three DA white dwarfs (2005)
Aznar Cuadrado, R., Jordan, S., Napiwotzki, R., Schmid, H. M., Solanki, S. K., Mathys, G.
Dobbie, P.D., Burleigh, Matthew R., Levan, Andrew J., Barstow, Martin A., Napiwotzki, R., Holberg, J.B., ...
Subluminous O Stars from the ESO Supernova Progenitor Survey - Observation versus Theory. (2005)
Stroeer, A., Heber, U., Lisker, T., Napiwotzki, R., Dreizler, S.
A near-IR spectrum of the DO white dwarf RE J0503-285. (2005)
Dobbie, P.D., Burleigh, M.R., Levan, A., Barstow, M.A., Napiwotzki, R., Hubeny, I.
Binaries discovered by the SPY project IV. Five single-lined DA double white dwarfs. (2005)
Nelemans, G., Napiwotzki, R., Karl, C., Marsh, T.R., Voss, B., Roelofs, G., ...
Two new ZZ Ceti pulsators from the HS and HE surveys. (2005)
Silvotti, R., Voss, B., Bruni, I., Koester, D., Reimers, D., Napiwotzki, R., ...
Wolf-Rayet and O star runaway populations from supernovae. (2005)
Dray, L.M., Dale, J.E., Beer, M.E., Napiwotzki, R., King, A.R.
Rotation velocities of white dwarfs determined from the Ca II K line. (2005)
Berger, L., Koester, D., Napiwotzki, R., Reid, I.N., Zuckerman, B.
Time-resolved Observations of the Short Period CV SDSS J123813.73-033933.0. (2005)
Zharikov, S.V., Tovmassian, G.H., Neustroev, V., Michel, R., Napiwotzki, R.
Kilo-Gauss Magnetic Fields in Three DA White Dwarfs. (2005)
Aznar Cuadrado, R., Jordan, S., Napiwotzki, R., Schmid, H.M., Solanki, S.K., Mathys, G.
DAZ White Dwarfs in the SPY Sample. (2005)
Koester, D., Rollenhagen, K., Napiwotzki, R., Voss, B., Christlieb, N., Homeier, D., ...
Subdwarf B Stars from the ESO Supernova Ia Progenitor Survey -- Observation versus Theory. (2005)
Lisker, T., Heber, U., Napiwotzki, R., Christlieb, N., Han, Z., Homeier, D., ...
The Mass of the sdB Primary of the Binary HS 2333+3927. (2005)
Heber, U., Drechsel, H., Karl, C., Ostensen, R., Folkes, S.L., Napiwotzki, R., ...
New Results from the Supernova Ia Progenitor Survey. (2005)
Napiwotzki, R., Karl, C., Nelemans, G., Yungelson, L., Christlieb, N., Drechsel, H., ...
Rotation Velocities of DA White Dwarfs with Convective Atmospheres. (2005)
Karl, C., Heber, U., Napiwotzki, R., Dreizler, S., Koester, D., Reid, I.N.
Rotation Velocities of DA White Dwarfs with Convective Atmospheres. (2005)
Karl, C., Heber, U., Napiwotzki, R., Dreizler, S., Koester, D., Reid, I.N.
Werner, K., Rauch, T., Napiwotzki, R., Christlieb, N., Reimers, D., Karl, C.
Original paper can be found at: http://astrosociety.org/pubs/cs/328.html Copyright ASP
HE 0437-5439: an unbound hypervelocity main-sequence B-type star. (2005)
Edelmann, H., Napiwotzki, R., Heber, U., Christlieb, N., Reimers, D.
Original article can be found at: http://www.iop.org/EJ/journal/apjl Copyright American Astronomical Society DOI: 10.1086/498940 [Full text of this article is not available in the UHRA]
A near-IR spectroscopic search for very-low-mass cool companions to notable DA white dwarfs (2004)
Dobbie, P. D., Burleigh, M. R., Levan, A. J., Barstow, M. A., Napiwotzki, R., Holberg, J. B., ...
We have undertaken a detailed near-IR spectroscopic analysis of eight notable white dwarfs, predominantly of southern declination. In each case the spectrum failed to reveal compelling evidence for...
A Close Binary Nucleus in the MOST Oxygen-Poor Planetary Nebula PN G135.9 55.9 (2004)
Tovmassian, G.H., Napiwotzki, R., Richer, M.G., Stasinska, G., Fullerton, A.W., Rauch, T.
Identification of a DO White Dwarf and a PG1159 Star in the ESO SN Ia Progenitor Survey (SPY) (2004)
Werner, K., Rauch, T., Napiwotzki, R., Christlieb, N., Reimers, D., Karl, C. A.
We present high-resolution VLT spectra of a new DO white dwarf and a new PG1159 star, which we identified in the ESO SPY survey. The PG1159 star is a low-gravity, extremely hot (Teff=160,000 K, log...
Praesepe and the seven white dwarfs (2004)
Dobbie, P. D., Pinfield, D. J., Napiwotzki, R., Hambly, N. C., Burleigh, M. R., Barstow, M. A., ...
We report the discovery, from our preliminary survey of the Praesepe open cluster, of two new spectroscopically confirmed white dwarf candidate members. We derive the effective temperatures and...
3D-Kinematics of White Dwarfs from the SPY-Project (2004)
Pauli, E-M., Heber, U., Napiwotzki, R., Altmann, M., Odenkirchen, M.
We present kinematics of a sample of 398 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...
Subluminous O stars from the ESO Supernova Progenitor Survey - Observation versus Theory (2004)
Stroeer, A., Heber, U., Lisker, T., Napiwotzki, R., Dreizler, S.
The ESO Supernova Progenitor Survey (SPY) has identified 58 (mostly helium-rich) subluminous O stars. We use the Balmer line strength to distinguish sdO from He-sdO (no Balmer lines) and present the...
Time-resolved observations of the short period CV SDSS J123813.73-033933 (2004)
Zharikov, S. V., Tovmassian, G. H., Neustroev, V., Michel, R., Napiwotzki, R.
We present simultaneous spectral and photometric observations of SDSS J123813.73-033933.0. From Ha radial velocity measurements we determined the orbital period of the system to be 0.05592+/-0.00002...
Lisker, T., Heber, U., Napiwotzki, R., Christlieb, N., Han, Z., Homeier, D., ...
We present the analysis of a high-resolution, high-quality sample of optical spectra for 76 subdwarf B (sdB) stars from the ESO Supernova Ia Progenitor Survey (SPY). Effective temperature, surface...
A close binary nucleus in the most oxygen-poor planetary nebula PN G 135.9+55.9 (2004)
Tovmassian, G. H., Napiwotzki, R., Richer, M. G., Stasinska, G., Fullerton, A. W., Rauch, T.
We report FUSE and new deep optical spectroscopic observations of PN G 135.9+55.9, the most oxygen-poor planetary nebula located in the Galactic halo. These observations allow us to estimate the...
Identification of a DO white dwarf and a PG1159 star in the ESO SN Ia progenitor survey (SPY) (2004)
Werner, K., Rauch, T., Napiwotzki, R., Christlieb, N., Reimers, D., Karl, C. A.
We present high-resolution VLT spectra of a new helium-rich DO white dwarf and a new PG1159 star, which we identified in the ESO SPY survey. We performed NLTE model atmosphere analyses and found that...
Werner, K., Rauch, T., Reiff, E., Kruk, J. W., Napiwotzki, R.
One of the strongest absorption lines observed in far-ultraviolet FUSE spectra of many PG1159 stars remained unidentified up to now. We show that this line, located at 973.3A, stems from NeVII. We...
HS 2333 3927: A new sdB dM binary with a large reflection effect (2004)
Heber, U., Drechsel, H., Ostensen, R., Karl, C., Napiwotzki, R., Altmann, M., ...
Close binary EHB stars from SPY (2004)
Napiwotzki, R., Karl, C., Lisker, T., Heber, U., Christlieb, N., Reimers, D., ...
Discovery of kilogauss magnetic fields in three DA white dwarfs (2004)
Cuadrado, R. Aznar, Jordan, S., Napiwotzki, R., Schmid, H. M., Solanki, S. K., Mathys, G.
We have detected longitudinal magnetic fields between 2 and 4 kG in three (WD 0446$-$790, WD 1105$-$048, WD 2359$-$434) out of a sample of 12 normal DA white dwarfs by using optical...
Double degenerates and progenitors of supernovae type Ia (2004)
Napiwotzki, R., Yungelson, L., Nelemans, G., Marsh, T. R., Leibundgut, B., Renzini, A., ...
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....
Spectral Types and Masses of White Dwarfs in Globular Clusters (2004)
Moehler, S., Koester, D., Zoccali, M., Ferraro, F. R., Heber, U., Napiwotzki, R., ...
White dwarfs in globular clusters offer additional possibilities to determine distances and ages of globular clusters, provided their spectral types and masses are known. We therefore started a...
Close binary EHB stars from SPY (2004)
Napiwotzki, R., Karl, C. A., Lisker, T., Heber, U., Christlieb, N., Reimers, D., ...
We present the results of a radial velocity (RV) survey of 46 subdwarf B (sdB) and 23 helium-rich subdwarf O (He-sdO) stars. We detected 18 (39%) new sdB binary systems, but only one (4%) He-sdO...
Close binary white dwarfs and supernovae IA (2004)
Christlieb , N., Drechsel , H., Heber , U., Homeier , D., Karl , C., Koester , D., ...
Informamos sobre el estado actual de los surveys" de velocidades radiales para binarias de enanas blancas (degeneradas dobles - DDs) incluyendo SPY (Exploración ESO de progenitoras de supernovas Ia)...
Discovery of kilogauss magnetic fields in three DA white dwarfs (2004)
Aznar Cuadrado, R., Jordan, S., Napiwotzki, R., Schmid, H.M., Solanki, S.K., Mathys, G.
Spectroscopic analysis of sdB stars from the ESO Supernova Ia Progenitor Survey (2004)
Lisker, T., Heber, U., Napiwotzki, R., Christlieb, N., Han, Z., Homeier, D., ...
Spectral types and masses of white dwarfs in globular clusters (2004)
Moehler, S., Koester, D., Zoccali, M., Ferraro, F.R., Heber, U., Napiwotzki, R., ...
Praesepe and the seven white dwarfs. (2004)
Dobbie, P.D., Pinfield, D.J., Napiwotzki, R., Hambly, N.C., Burleigh, M.R., Barstow, M.A., ...
Double Degenerate and Progenitors of Supernovae Type Ia. (2004)
Napiwotzki, R., Yungelson, L., Nelemans, G., Marsh, T.R., Leibundgut, B., Renzini, A., ...
HS 2333 + 3927: a new sdB binary with a large reflection effect. (2004)
Karl, C., Heber, U., Drechsel, H., Napiwotzki, R., Altmann, M., Ostensen, R., ...
“The original publication is available at www.springerlink.com”. Copyright Springer. DOI: 10.1023/B:ASTR.0000044334.98860.ab [Full text of this article is not available in the UHRA]
FUSE Observations of EC14026 Stars. (2004)
Chayer, P., Fontaine, G., Fontaine, M., Lamontagne, R., Wesemael, F., Dupuis, J., ...
“The original publication is available at www.springerlink.com”. Copyright Springer. DOI: 10.1023/B:ASTR.0000044344.92680.b8 [Full text of this article is not available in the UHRA]
2MASS J0516288+260738: Discovery of the first eclipsing late K + Brown dwarf binary system (2003)
Schuh, S.L., Handler, G., Drechsel, H., Hauschildt, P., Dreizler, S., Medupe, R., ...
Spectroscopic analysis of sdB stars from the ESO Supernova Ia Progenitor Survey (2003)
Lisker, T., Heber, U., Napiwotzki, R., Christlieb, N., Reimers, D., Homeier, D.
We report on the analysis of high-resolution optical spectra for 77 subdwarf B (sdB) stars from the ESO Supernova Ia Progenitor Survey. Effective temperature, surface gravity, and photospheric helium...
Karl, C. A., Napiwotzki, R., Nelemans, G., Christlieb, N., Koester, D., Heber, U., ...
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...
2MASSJ0516288+260738: Discovery of the first eclipsing late K + Brown dwarf system? (2003)
Schuh, S. L., Handler, G., Drechsel, H., Hauschildt, P. H., Dreizler, S., Medupe, R., ...
We report the discovery of a new eclipsing system less than one arcminute south of the pulsating DB white dwarf KUV 05134+2605. The object could be identified with the point source...
Heavy-element abundance patterns in hot DA white dwarfs (2003)
Barstow, M.A., Good, S.A., Holberg, J.B., Hubeny, I., Bannister, N.P., Bruhweiler, F.C., ...
Spectral analysis of sdB Stars from the Hamburg Quasar Survey (2003)
Edelmann, H., Heber, U., Hagen, H.J., Dreizler, S., Napiwotzki, R., Engels, D., ...
3D kinematics of white dwarfs from the SPY project (2003)
Pauli, E.M., Napiwotzki, R., Altmann, M., Heber, U., Odenkirchen, M., Kerber, F.
Spectral analysis of sdB stars from the Hamburg Quasar Survey (2003)
Edelmann, H., Heber, U., Lemke, M., Dreizler, S., Napiwotzki, R., ...
We present the results of a spectral analysis of a large sample of subdwarf B stars selected from follow-up observations of candidates from the Hamburg Quasar Survey. Fundamental parameters...
Heavy element abundance patterns in hot DA white dwarfs (2003)
Barstow, M. A., Good, S. A., Holberg, J. B., Hubeny, I., Bannister, N. P., Bruhweiler, F. C., ...
We present a series of systematic abundance measurements for 25 hot DA white dwarfs in the temperature range ~20000-110000K, based on far-UV spectroscopy with STIS/GHRS on HST, IUE and FUSE. Using...
3D kinematics of white dwarfs from the SPY project (2003)
Napiwotzki, R., Altmann, M., Heber, U., Odenkirchen, M., Kerber, F.
We present kinematics of a sample of 107 DA white dwarfs from the SPY project and discuss kinematic criteria for a distinction of thin disk, thick disk, and halo populations. This is the first...
Heavy-element abundance patterns in hot DA white dwarfs (2003)
Barstow, Martin A., Good, S.A., Holberg, J.B., Hubeny, I., Bannister, N.P., Bruhweiler, F.C., ...
NLTE Spectral Analysis of Iron Group Elements in the Hot Subluminous O-star BD+28 4211. (2003)
Ramspeck, M., Haas, S., Napiwotzki, R., Heber, U., Deetjen, J., Dreizler, S.
Search for double degenerate progenitors of supernovae type Ia with SPY (2002)
Napiwotzki, R., Christlieb, N., Drechsel, H., Heber, U., Homeier, D., ...
We report on a large survey for double degenerate (DD) binaries as potential progenitors of type Ia supernovae with the UVES spectrograph at the ESO VLT (SN Ia Progenitor surveY - SPY). About 560...
Search for double degenerate progenitors of supernovae type Ia with SPY (2002)
Napiwotzki, R., Drechsel, H., Heber, U., Karl, C., Christlieb, N., ...
We report on 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).
Double degenerates from the supernova Ia progenitor survey (SPY) (2002)
Karl, C., Napiwotzki, R., Heber, U., Lisker, T., Nelemans, G., Christlieb, N., ...
We report on follow-up observations of double degenerate (DD) white dwarfs from the Supernovae Ia Progenitor Survey (SPY). Orbital parameters of four systems, including a massive short period system,...
Napiwotzki, R., Koester, D., Nelemans, G., Yungelson, L., Christlieb, N., Renzini, A., ...
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...
Search for progenitors of supnernovae type Ia with SPY (2002)
Napiwotzki, R., Christlieb, N., Drechsel, H., Heber, U., Homeier, D., ...
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...
Resolving subdwarf B stars in binaries by HST imaging (2002)
Heber, U., Moehler, S., Napiwotzki, R., Thejll, P., Green, E.
Resolving subdwarf B stars in binaries by HST imaging (2002)
Heber, U., Moehler, S., Napiwotzki, R., Thejll, P., Green, E. M.
The origin of subluminous B stars is still an unsolved problem in stellar evolution. Single star as well as close binary evolution scenarios have been invoked but until now have met with little...
Extremely Faint Blue-tail Stars in Centauri. (2002)
Moehler, S., Napiwotzki, R., Sweigart, A.V., Landsman, S., Dreizler, S.
HS 0705 6700: A new eclipsing sdB binary (2001)
Drechsel, H., Heber, U., Napiwotzki, R., Ostensen, R., Solheim, J.E., Johannessen, F., ...
HS 0705+6700: a new eclipsing sdB binary (2001)
Drechsel, H., Heber, U., Napiwotzki, R., Ostensen, R., Johannessen, F., ...
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,...
Binaries discovered by the SPY project. I. HE 1047-0436: A subdwarf B white dwarf syste (2001)
Napiwotzki, R., Edelmann, H., Heber, U., Karl, C., Drechsel, H., Pauli, E.M., ...
Binaries discovered by the SPY project I. HE 1047-0436: a subdwarf B + white dwarf system (2001)
Napiwotzki, R., Edelmann, H., Heber, U., Karl, C., Drechsel, H., ...
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...
UITBOC 1574: A Very Distant Helium- poor Subdwarf O Star (2001)
Seibert, M., Chayer, P., Meurer, G.R., Saffer, R., Napiwotzki, R.
Search for progenitors of supernovae type Ia with SPY (2001)
Napiwotzki, R., Christlieb, N., Drechsel, H., Heber, U., Homeier, D., ...
Heavy Elements in DA White Dwarfs. (2001)
Barstow, M.A., Burleigh, M.R., Bannister, N.P., Holberg, J.B., Hubeny, I., Bruhweiler, F.C., ...
Spectral Analysis of sdB Stars from the Hamburg ESO Survey. (2001)
Edelmann, H., Heber, U., Napiwotzki, R., Lemke, M., Christlieb, N.
Metal abundances of sdB stars. (2001)
Edelmann, H., Heber, U., Napiwotzki, R.
Original article can be found at: http://www3.interscience.wiley.com Copyright WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/1521-3994(200112)322:5/63.0.CO;2-M Full text of this article is...
Search for progenitors of supernovae type Ia with SPY. (2001)
Napiwotzki, R., Christlieb, N., Drechsel, H., Hagen, H.J., Heber, U., Homeier, D., ...
‘The definitive version is available at www3.interscience.wiley.com .' Copyright WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/1521-3994(200112)322:5/63.0.CO;2-I [Full text of this...
Heavy element abundances in DA white dwarfs (2000)
Barstow, M. A., Burleigh, M. R., Bannister, N. P., Holberg, J. B., Hubeny, I., Bruhweiler, F. C., ...
We present a series of systematic abundance measurements for a group of hot DA white dwarfs in the temperature range 20,000-75,000K, based on far-UV spectroscopy with STIS on HST, IUE and FUSE. Using...
First VLT spectra of white dwarfs in a globular cluster (2000)
Moehler, S., Heber, U., Napiwotzki, R., Koester, D., Renzini, A.
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...
First VLT spectra of white dwarfs in a globular cluster. (2000)
Moehler, S., Heber, U., Napiwotzki, R., Koester, D., Renzini, A.
Optical spectroscopy of the candidate luminous white dwarf in the young LMC cluster NGC1818 (1999)
Burleigh, M. R., Saffer, R. A., Gilmore, G. F., Napiwotzki, R.
An optical spectrum of the Elson et al. (1998) candidate luminous white dwarf in the young LMC cluster NGC1818 shows conclusively that it is not a degenerate star. A model atmosphere fit gives...
Masses and Other Parameters of the PostCommon Envelope Binary BE Ursae Majoris. (1999)
Ferguson, D.H., Liebert, J., Haas, S., Napiwotzki, R., James, T.A.
Spectral analysis of hot subluminous stars. (1999)
Heber, U., Edelmann, H., Lemke, M., Napiwotzki, R., Engels, D.
Spectral analysis of the binary sdB star Feige 36. (1999)
Edelmann, H., Heber, U., Napiwotzki, R., Reid, I.N., Saffer, R.
Moehler, S., Heber, U., Lemke, M., Napiwotzki, R.
Two UV brights stars in globular clusters, ROA 5701 (omega 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...
The UV bright star ZNG 1 in M 5 (1998)
We report the results of H_alpha imaging and UV spectroscopy with the Hubble Space Telescope of the hot post-AGB star ZNG 1 in M 5 and its suspected planetary nebula.
Hot UV bright stars in globular clusters (1998)
Moehler, S., Landsman, W., Napiwotzki, R.
We have obtained medium-resolution spectra of seven UV-bright stars discovered on images of four southern globular clusters obtained with the Ultraviolet Imaging Telescope (UIT). Effective...
Temperature determination of the cool DO white dwarf HD149499B from EUVE observations (1996)
Jordan, S., Napiwotzki, R., Koester, D., Rauch, T.
We present a LTE model atmosphere analysis of the medium and long wavelength spectrum of the cool DO white dwarf HD149499B. This observation in the spectral range 230-700 A supplements a previous...
NLTE spectral analysis of helium-rich sdO stars from the southern HK survey. (1996)
Drilling, J.S., Napiwotzki, R., Dreizler, S., Heber, U., Beers, T.C.