Gemini spectra of 12 000 K white dwarf stars

  title={Gemini spectra of 12 000 K white dwarf stars},
  author={S. O. Kepler and B{\'a}rbara Garcia Castanheira and A. F. M. Costa and Detlev Koester},
  journal={Monthly Notices of the Royal Astronomical Society},
We report signal-to-noise ratio (S/N) ≃ 100 optical spectra for four DA white dwarf stars acquired with the GMOS spectrograph of the 8-m Gemini north telescope. These stars have 18 < g < 19 and are around T eff ∼ 12 000 K, where the hydrogen lines are close to maximum. Our purpose is to test if the effective temperatures and surface gravities derived from the relatively low-S/N ((S/N) ≈ 21) optical spectra acquired by the Sloan Digital Sky Survey through model atmosphere fitting are trustworthy… 

Figures and Tables from this paper

White dwarf mass distribution in the SDSS
We determined masses for the 7167 DA and 507 DB white dwarf stars classified as single and non-magnetic in Data Release 4 of the Sloan Digital Sky Survey (SDSS). We obtained revised T eff and log g
New pulsating ZZ ceti stars
Over the last four years the number of known pulsating DA white dwarf stars increased from 32 to a total of 147; 87 are white dwarf stars identified by the Sloan Digital Sky Survey and selected from
Post-common-envelope binaries from SDSS – I. 101 white dwarf main-sequence binaries with multiple Sloan Digital Sky Survey spectroscopy
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
Using recent photometric calibrations, we develop greatly improved distance estimates for DA white dwarfs using multi-band synthetic photometry based on spectroscopic temperatures and gravities. Very
Pulsating White Dwarf Stars and Precision Asteroseismology
Galactic history is written in the white dwarf stars. Their surface properties hint at interiors composed of matter under extreme conditions. In the forty years since their discovery, pulsating white
Seismological studies of ZZ Ceti stars
We calculate an extensive adiabatic model grid for pulsating white dwarfs with H dominated atmospheres, the ZZ Ceti stars. We developed a new approach for asteroseismology, using the relative
New developments of the ZZ Ceti instability strip : the discovery of 11 new variables
Using the The SOuthern Astrophysical Research (SOAR) 4.1-m telescope, we report on the discovery of low amplitude pulsations for three stars previously reported as not-observed-to-vary (NOV) by
Post-common envelope binaries from SDSS-X: The origin of low-mass white dwarfs
We present the first white dwarf mass distributions of a large and homogeneous sample of post-common envelope binaries (PCEBs) and wide white dwarf main-sequence (WDMS) binaries directly obtained
Unified line profiles for hydrogen perturbed by collisions with protons: satellites and asymmetries
We present new calculations of unified line profiles for hydrogen perturbed by collisions with protons. We report on new calculations of the potential energies and dipole moments which allow the
The cool ZZ Ceti star PG 2303+243: Observations and analysis of variability in 2004
PG 2303+243 is a cool DA variable (also called ZZ Ceti) star with a rich pulsation spectrum and variable amplitudes. A mini-campaign involving six observatories yielded time-resolved photometric


Mass distribution of DA white dwarfs in the first Data Release of the Sloan Digital Sky Survey
We investigate the sample of 1175 new nonmagnetic DA white dwarfs with the effective temperatures $T_{\rm eff} \ge 12\,000$ K, which were extracted from the Data Release 1 of the Sloan Digital Sky
Thirty-Five New Pulsating DA White Dwarf Stars
We present 35 new pulsating DA (hydrogen atmosphere) white dwarf stars discovered from the Sloan Digital Sky Survey (SDSS) and the Hamburg Quasar Survey (HQS). We have acquired high-speed time series
Eleven New DA White Dwarf Variable Stars from the Sloan Digital Sky Survey
We report the discovery of 11 new variable DA white dwarf (ZZ Ceti) stars. Candidates were selected by deriving temperatures from model fits to spectra obtained from the Sloan Digital Sky Survey
On the Purity of the ZZ Ceti Instability Strip: Discovery of More Pulsating DA White Dwarfs on the Basis of Optical Spectroscopy
We report the discovery of two new ZZ Ceti pulsators, LP 133-144 and HE 1258+0123, selected on the basis of model atmosphere fits to optical spectroscopic data. The atmospheric parameters for LP
The Space Telescope Science Institute
A description of the planning and development of a small, specialized research library serves the scientists at the Space Telescope Science Institute and its services and collection are discussed.
A Catalog of Spectroscopically Identified White Dwarf Stars in the First Data Release of the Sloan Digital Sky Survey
We present the full spectroscopic white dwarf and hot subdwarf sample from the Sloan Digital Sky Survey (SDSS) first data release, DR1. We find 2551 white dwarf stars of various types, 240 hot
Interstellar extinction in the UV
Theoretical white dwarf luminosity functions: DA models
New DA white dwarf models with thick H and He surface layers are presented. Uncertainties in cool WD ages resulting from the lack of opacities in the weakly degenerate regime are estimated at ∼10%.