Browsing Research publications by Author "Koester, D."

Now showing items 21-29 of 29

    • Rotation velocities of white dwarfs. III. DA stars with convective atmospheres 

      Karl, C.; Napiwotzki, R.; Heber, U.; Dreizler, S.; Koester, D.; Reid, I.N. (2005-05)

    • Search for progenitors of supernovae type Ia with SPY 

      Napiwotzki, R.; Christlieb, N.; Drechsel, H.; Hagen, H.J.; Heber, U.; Homeier, D.; Karl, C.; Koester, D.; Leibundgut, B.; Marsh, T.R.; Moehler, S.; Nelemans, G.; Pauli, E.M.; Reimers, D.; Renzini, A.; Yungelson, L. (2001)

    • A search for white dwarfs in the Galactic plane: : the field and the open cluster population 

      Raddi, R.; Catalan, S.; Gaensicke, B. T.; Hermes, J. J.; Napiwotzki, R.; Koester, D.; Tremblay, P. -E.; Barentsen, G.; Farnhill, H. J.; Mohr-Smith, M.; Drew, J. E.; Groot, P. J.; Guzman-Ramirez, L.; Parker, Q. A.; Steeghs, D.; Zijlstra, A. (2016-04-01)
      We investigated the prospects for systematic searches of white dwarfs at low Galactic latitudes, using the VLT Survey Telescope (VST) H$\alpha$ Photometric Survey of the Galactic plane and Bulge (VPHAS+). We targeted 17 ...

    • Serendipitous discovery of a dusty disc around WDJ181417.84-735459.83 

      Egea, E. González; Koester, D.; Rogers, L. K.; Marocco, F.; Cooper, W. J.; Beamin, J. C.; Burningham, B.; Day-Jones, A.; Forbrich, J.; Pinfield, D. J. (2020-12-12)
      Spectroscopic observations of white dwarfs reveal that many of them are polluted by exoplanetary material, whose bulk composition can be uniquely probed this way. We present a spectroscopic and photometric analysis of the ...

    • Six New ZZ Ceti Stars from the SPY and the HQS Surveys 

      Voss, B.; Koester, D.; Ostensen, R.; Napiwotzki, R.; Homeier, D.; Reimers, D. (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 ...

    • Spectral types and masses of white dwarfs in globular clusters 

      Moehler, S.; Koester, D.; Zoccali, M.; Ferraro, F.R.; Heber, U.; Napiwotzki, R.; Renzini, A. (2004)

    • SPY - the ESO Supernovae type Ia Progenitor survey 

      Napiwotzki, R.; Christlieb, N.; Drechsel, H.; Hagen, H.J.; Heber, U.; Homeier, D.; Karl, C.; Koester, D.; Leibundgut, B.; Marsh, T.R.; Moehler, S.; Nelemans, G.; Pauli, E.M.; Reimers, D.; Renzini, A.; Yungelson, L. (2003)
      Supernovae (SNe) mark the violent termination of a star’s life in an explosion. They are classified according to their light curve as type I or II, with the type I SNe producing very similar light curves, while the SNe ...

    • Temperature determination of the cool DO white dwarf HD 149499B from EUVE observations 

      Jordan, S.; Napiwotzki, R.; Koester, D.; Rauch, T. (1997)
      We present a LTE model atmosphere analysis of the EUVE medium and long wavelength spectrum of the cool DO white dwarf HD149499B. This observation in the spectral range 230-700°A supplements a previous analysis of an ORFEUS ...

    • Two new ZZ Ceti pulsators from the HS and HE surveys 

      Silvotti, R.; Voss, B.; Bruni, I.; Koester, D.; Reimers, D.; Napiwotzki, R.; Homeier, D. (2005)