Rebassa-Mansergas, A., Gaensicke, B. T., Schreiber, M. R., Koester, D., Rodriguez-Gil, P.
We present a catalogue of 1602 white dwarf-main sequence binaries (WDMS) from the spectroscopic Sloan Digital Sky Survey Data Release 6 (SDSS DR6). Among these we identify 440 as new WDMS binaries....
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...
Detecting short period variable stars with Gaia (2009)
Varadi, M., Eyer, L., Jordan, S., Mowlavi, N., Koester, D.
We analyzed the frequency domain of time series of simulated ZZ Ceti light-curves to investigate the detectability and period recovery performance of short period variables (periods < 2 hours) for...
A number of cool white dwarfs with metal traces, of spectral types DAZ, DBZ, and DZ have been found to exhibit infrared excess radiation due to circumstellar dust. The origin of this dust is possibly...
Neural circuits of hierarchical visuo-spatial sequence processing (2009)
Bahlmann, Jörg, Schubotz, Ricarda I., Mueller, J. L., Koester, D., Friederici, Angela D.
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
Post Common Envelope Binaries from SDSS. V: Four eclipsing white dwarf main sequence binaries (2008)
Pyrzas, S., Gänsicke, B. T., Marsh, T. R., Aungwerojwit, A., Rebassa-Mansergas, A., Rodríguez-Gil, P., ...
We identify SDSS011009.09+132616.1, SDSS030308.35+005444.1, SDSS143547.87+373338.5 and SDSS154846.00+405728.8 as four eclipsing white dwarf plus main sequence (WDMS) binaries from the Sloan Digital...
SDSS White Dwarf mass distribution at low effective temperatures (2008)
Koester, D., Kepler, S. O., Kleinman, S. J., Nitta, A.
The DA white dwarfs in the Sloan Digital Sky Survey, as analyzed in the papers for Data Releases 1 and 4, show an increase in surface gravity towards lower effective temperatures below 11500 K. We...
SDSSJ084539.17+225728.0: the first DBZ white dwarf with a metal-rich gaseous debris disc (2008)
Gaensicke, B. T., Koester, D., Marsh, T. R., Rebassa-Mansergas, A., Southworth, J.
We report the discovery of a third white dwarf hosting a gaseous debris disc, SDSSJ084539.17+225728.0. The typical double-peaked CaII 8498,8542,8662A emission lines can be modelled in terms of a...
MAD@VLT: Deep into the Madding Crowd of Omega Centauri (2008)
Bono, G., Calamida, A., Corsi, C. E., Stetson, P. B., Marchetti, E., Amico, P., ...
We present deep and accurate Near-Infrared (NIR) photometry of the Galactic Globular Cluster (GC) Omega Cen. Data were collected using the Multi-Conjugate Adaptive Optics Demonstrator (MAD) on VLT...
The Absolute Flux Distribution of LDS749B (2008)
Observations from the Space Telescope Imaging Spectrograph define the flux of the DBQ4 star LDS749B from 0.12-1.0 \mu m with an uncertainty of ~1% relative to the three pure hydrogen WD primary HST...
On the radial distribution of white dwarfs in the Galactic globular cluster Omega Cen (2007)
Calamida, A., Corsi, C. E., Bono, G., Stetson, P. B., Moroni, P. G. Prada, Degl'Innocenti, S., ...
We present deep and accurate photometry (F435W, F625W, F658N) of the Galactic Globular Cluster Omega Cen collected with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope...
On the white dwarf cooling sequence of the globular cluster Omega Centauri (2007)
Calamida, A., Corsi, C. E., Bono, G., Stetson, P. B., Moroni, P. G. Prada, Degl'Innocenti, S., ...
We present deep and precise photometry (F435, F625W, F658N) of Omega Cen collected with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST). We have identified ~ 6,500...
The Hubbl, E Space, T El Escope, S. O. Kepler, E. L. Robinson, D. Koester, ...
We have obtained time-resolved ultraviolet spectroscopy for the pulsating DAV stars G226-29 and G185-32 and for the pulsating DBV star PG 1351]489 with the Hubble Space T elescope Faint Object...
Schreiber, M. R., Gaensicke, B. T., Southworth, J., Schwope, A. D., Koester, D.
The Sloan Digital Sky Survey turned out to be very efficient in identifying white dwarf/main sequence binaries (WDMS). The population of WDMS systems consists of wide systems whose stellar components...
The pre-cataclysmic variable, LTT560 (2007)
Tappert, C., Gaensicke, B. T., Schmidtobreick, L., Aungwerojwit, A., Mennickent, R. E., Koester, D.
System parameters of the object LTT560 are determined in order to clarify its nature and evolutionary status. We apply time-series photometry to reveal orbital modulations of the light curve,...
The Chemical Composition of an Extrasolar Minor Planet (2007)
Zuckerman, B., Koester, D., Melis, C., Hansen, B., Jura, M.
We report the relative abundances of 17 elements in the atmosphere of the white dwarf star GD 362, material that, very probably, was contained previously in a large asteroid or asteroids with...
Rebassa-Mansergas, A., Gaensicke, B. T., Rodriguez-Gil, P., Schreiber, M. R., Koester, D.
We present a detailed analysis of 101 white dwarf-main sequence binaries (WDMS) from the Sloan Digital Sky Survey (SDSS) for which multiple SDSS spectra are available. We detect significant radial...
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...
XMM-Newton observations of EF Eridani: the textbook example of low-accretion rate polars (2007)
Schwope, A. D., Staude, A., Koester, D., Vogel, J.
Archival X-ray observations of EF Eridani obtained in a low state revealed distinct X-ray detections at a luminosity L_X ~ 2 10^{29} erg/s, three orders of magnitude below its high state value. The...
Velocity Fields at the Surface of ZZ Ceti Stars (2007)
We demonstrate that the peculiar line profiles observed in DA white dwarfs in the temperature range of the ZZ Ceti variables can be explained by the surface velocity fields associated with the...
Binary White Dwarfs in the Supernova Ia Progenitor Survey. (2007)
Napiwotzki, R., Karl, C., Nelemans, G., Yungelson, L., Christlieb, N., Drechsel, H., ...
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.
White Dwarf Mass Distribution in the SDSS (2006)
Kepler, S. O., Kleinman, S. J., Nitta, A., Koester, D., Castanheira, B. G., Giovannini, O., ...
We determined masses for the 7167 DA and 507 DB white dwarf stars classified as single and non-magnetic in data release four of the Sloan Digital Sky Survey (SDSS). We obtained revised Teff and log g...
The Lowest Mass White Dwarf (2006)
Kilic, Mukremin, Prieto, Carlos Allende, Brown, Warren R., Koester, D.
Extremely low mass white dwarfs are very rare objects likely formed in compact binary systems. We present MMT optical spectroscopy of 42 low mass white dwarf candidates serendipitously discovered in...
Towards a pure ZZ Ceti instability strip (2006)
Castanheira, B. G., Kepler, S. O., Costa, A. F. M., Giovannini, O., Robinson, E. L., Winget, D. E., ...
We have observed again two stars inside the ZZ Ceti instability strip that were previously classified as not-observed-to-vary (NOV) by Mukadam et al. (2004) and found them to be low-amplitude...
Gemini spectra of 12000K white dwarf stars (2006)
Kepler, S. O., Castanheira, B. G., Costa, A. F. M., Koester, D.
We report signal-to-noise ratio SNR ~ 100 optical spectra for four DA white dwarf stars acquired with the GMOS spectrograph of the 8m Gemini north telescope. These stars have 18
New DQ white dwarfs in the Sloan Digital Sky Survey DR4: confirmation of two sequences (2006)
Using photometric selection criteria, and in a final step visual inspection of spectra, we find 65 DQ white dwarfs in the Data Release 4 of the Sloan Digital Sky Survey. 37 of these are new...
The masses of PSR J1911-5958A and its white dwarf companion (2006)
Bassa, C. G., Van Kerkwijk, M. H., Koester, D., Verbunt, F.
We present spectroscopic and photometric observations of the optical counterpart to PSR J1911-5958A, a millisecond pulsar located towards the globular cluster NGC 6752. We measure radial velocities...
The accretion-diffusion scenario for metals in cool white dwarfs (2006)
We calculated diffusion timescales for Ca, Mg, Fe in hydrogen atmosphere white dwarfs with temperatures between 5000 and 25000 K. With these timescales we determined accretion rates for a sample of...
Analysis of IUE spectra of helium-rich white dwarf stars (2006)
Castanheira, B. G., Kepler, S. O., Handler, G., Koester, D.
We studied the class of DB white dwarf stars, using re-calibrated UV spectra for thirty four DBs obtained with the IUE satellite. By comparing the observed energy distributions with model...
Discovery of eleven new ZZ Ceti stars. (2006)
Castanheira, B.G., Kepler, S.O., Mullally, F., Winget, D.E., Koester, D., Voss, B., ...
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., ...
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,...
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...
HS 0146 1847 - a DAZB white dwarf of very unusual composition (2005)
Koester, D., Napiwotzki, R., Voss, B., Homeier, D., Reimers, D.
Hubble Space Telescope Spectroscopy of the Balmer lines in Sirius B (2005)
Barstow, M. A., Bond, Howard E., Holberg, J. B., Burleigh, M. R., Hubeny, I., Koester, D.
Sirius B is the nearest and brightest of all white dwarfs, but it is very difficult to observe at visible wavelengths due to the overwhelming scattered light contribution from Sirius A. However, from...
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...
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.
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., ...
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., ...
Hubble Space Telescope spectroscopy of the Balmer lines in Sirius B (2005)
Barstow, Martin A., Bond, Howard E., Holberg, J.B., Burleigh, Matthew R., Hubeny, I., Koester, 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., ...
Rotation velocities of white dwarfs determined from the Ca II K line. (2005)
Berger, L., Koester, D., Napiwotzki, R., Reid, I.N., Zuckerman, B.
DAZ White Dwarfs in the SPY Sample. (2005)
Koester, D., Rollenhagen, K., Napiwotzki, R., Voss, B., Christlieb, N., 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.
Do Magnetic Fields Prevent Hydrogen from Accreting onto Cool Metal-line White Dwarf Stars? (2004)
Friedrich, S., Jordan, S., Koester, D.
It is generally assumed that metals detected in the spectra of a few cool white dwarfs cannot be of primordial origin and must be accreted from the interstellar medium. However, the observed...
Lawton, R., Krueger, R., Koester, D.
MEMS fabrication processes are as diverse as their applications.
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., ...
The Peculiar Pulsations of PY Vul (2004)
Thompson, Susan E., Clemens, J. C., Van Kerkwijk, M. H., O'Brien, M. Sean, Koester, D.
The pulsating white dwarf star PY Vul (G~185-32) exhibits pulsation modes with peculiar properties that set it apart from other variable stars in the ZZ Ceti (DAV) class. These peculiarities include...
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...
Kleinman, S. J., Harris, Hugh C., Eisenstein, Daniel J., Liebert, James, Nitta, Atsuko, Krzesiński, Jurek, ...
We present the full spectroscopic white dwarf and hot subdwarf sample from the SDSS first data release, DR1. We find 2551 white dwarf stars of various types, 240 hot subdwarf stars, and an additional...
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)...
Spectral types and masses of white dwarfs in globular clusters (2004)
Moehler, S., Koester, D., Zoccali, M., Ferraro, F.R., Heber, U., Napiwotzki, R., ...
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]
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...
The DA+dMe eclipsing binary EC13471-1258: its cup runneth over...just (2003)
O'Donoghue, D., Koen, C., Kilkenny, D., Stobie, R. S., Koester, D., Bessell, M. S., ...
EC13471-1258 is a detached eclipsing binary with Porb = 3h37m, comprising a DA white dwarf and a dMe dwarf. Total eclipses of the white dwarf lasting 14 min, and a large amplitude ellipsoidal...
High Resolution Spectroscopy of the Pulsating White Dwarf G29-38 (2003)
Thompson, Susan E., Clemens, J. C., Van Kerkwijk, M. H., Koester, D.
We present the analysis of time-resolved, high resolution spectra of the cool white dwarf pulsator, G29-38. From measuring the Doppler shifts of the H-alpha core, we detect velocity changes as large...
Model atmosphere analysis of the extreme DQ white dwarf GSC2U J131147.2+292348 (2003)
Carollo, D., Koester, D., Spagna, A., Lattanzi, M. G., Hodgkin, S. T.
A new model atmosphere analysis for the peculiar DQ white dwarf discovered by Carollo et al. (2002) is presented. The effective temperature and carbon abundance have been estimated by fitting both...
Kotak, R., Van Kerkwijk, M. H., Clemens, J. C., Koester, D.
We report on our findings of the bright, pulsating, helium atmospherewhite dwarf GD 358, based on time-resolved optical spectrophotometry. Weidentify 5 real pulsation modes and at least 6 combination...
Wavelength dependence of pulsation amplitudes in DBV white dwarfs (2003)
Koester, D., Weidner, C., Ising, J., Kotak, R.
Not Available
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).
Element abundances in cool white dwarfs. II. Ultraviolet observations of DZ white dwarfs (2002)
Wolff, B., Koester, D., Liebert, J.
We present a small data base of homogeneously derived photospheric element abundances of DZ white dwarfs and related objects. Our previous investigations are supplemented with the analysis of...
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...
Lemoine, M., Vidal-Madjar, A., Hebrard, G., Ferlet, R., Etangs, A. Lecavelier Des, ...
High-resolution spectra of the hot white dwarf G191-B2B, covering the wavelength region 905-1187A, were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). This data was used in...
Nonlinear effects in time-resolved spectra of DAVs (2001)
Numerical simulations of light curves of variable DA white dwarfs (ZZ Ceti stars) predict flux amplitudes with surface distributions different from the spherical harmonics of the pulsation mode in...
FUSE observations of hot white dwarfs (2001)
Wolff, B., Kruk, J. W., Koester, D., Allard, N. F., Ferlet, R., Vidal-Madjar, A.
We have analyzed FUSE observations of six hot white dwarf stars: four DA white dwarfs with T_eff >= 45000K, the DAO Feige55 (T_eff = 55000K), and the DA CD -38 10980 (T_eff = 24000K). Photospheric...
Search for progenitors of supernovae type Ia with SPY (2001)
Napiwotzki, R., Christlieb, N., Drechsel, H., Heber, U., Homeier, D., ...
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...
The stellar content of the Hamburg/ESO survey. I. Automated selection of DA white dwarfs (2000)
Christlieb, N., Wisotzki, L., Reimers, D., Homeier, D., Koester, D., Heber, U.
We describe automatic procedures for the selection of DA white dwarfs in the Hamburg/ESO objective-prism survey (HES). For this purpose, and the selection of other stellar objects (e.g., metal-poor...
Cool helium-rich white dwarfs from the Hamburg/ESO Survey (2000)
Friedrich, S., Koester, D., Christlieb, N., Reimers, D., Wisotzki, L.
We present an analysis of 40 cool helium-rich white dwarfs found in the Hamburg/ESO survey. They were selected for follow-up spectroscopy because of their U-B colour below -0.18, the absence of...
Mode identification of Pulsating White Dwarfs using the HST (2000)
Kepler, S. O., Robinson, E. L., Koester, D., Clemens, J. C., Nather, R. E., Jiang, X. J.
We have obtained time-resolved ultraviolet spectroscopy for the pulsating DAV stars G226-29 and G185-32, and for the pulsating DBV star PG1351+489 with the Hubble Space Telescope Faint Object...
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.
Hebrard, G., Mallouris, C., Ferlet, R., Koester, D., Lemoine, M., Vidal-Madjar, A., ...
We present new observations of the binary Sirius A / Sirius B performed with HST-GHRS. Two interstellar clouds are detected on this sightline, one of them being identified as the Local Interstellar...
Detection of spatial variations in the (D/H) ratio in the local interstellar medium (1998)
Vidal-Madjar, A., Lemoine, M., Ferlet, R., Hebrard, G., Koester, D., Audouze, J., ...
We present high spectral resolution HST-GHRS observations of the white dwarf G191-B2B, and derive the interstellar D/H ratio on the line of sight. We have observed and analysed simultaneously the...
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...
Discovery of four white dwarfs with strong magnetic fields by the Hamburg/ESO Survey (1996)
Reimers, D., Jordan, S., Koester, D., Bade, N., Koehler, Th., Wisotzki, L.
Four magnetic white dwarfs have been found in the course of the Hamburg/ESO Survey for bright QSOs. The objects have been selected as QSO candidate on the basis of its blue continuum and the apparent...
Quasi-molecular Satellites of Lyman Beta in the Spectrum of the DA White Dwarf WOLF 1346 (1996)
Koester, D., Finley, D. S., Allard, N. F., Kruk, J. W., Kimble, R. A.
We present new FUV/UV observations of the DA white dwarf Wolf 1346 obtained with the Hopkins Ultraviolet Telescope. The atmospheric parameters of this object are estimated from a fit of model...
WHITE DWARFS OBSERVED BY HIPPARCOS G. Vauclair
Schmidt Koester Allard, G. Vauclair, H. Schmidt, D. Koester, N. Allard
The Hipparcos satellite has measured trigonometric parallaxes for 20 white dwarfs. With the exception of one each of the spectral types DZ, DC, DB, DQ, the majority are of spectral type DA. We...