The pulsation modes of the pre-white dwarf PG 1159-035 (2008)
Costa, J. E. S., Kepler, S. O., Winget, D. E., O'Brien, M. S., Kawaler, S. D., Costa, A. F. M., ...
Context. PG 1159-035, a pre-white dwarf with T_(eff) ≃ 140 000 K, is the prototype of both two classes: the PG 1159 spectroscopic class and the DOV pulsating class. Previous studies of PG 1159-035...
The pulsation modes of the pre-white dwarf PG 1159-035 (2007)
Costa, J. E. S., Kepler, S. O., Winget, D. E., O'Brien, M. S., Kawaler, S. D., Costa, A. F. M., ...
PG 1159-035, a pre-white dwarf with T_eff=140,000 K, is the prototype of both two classes: the PG1159 spectroscopic class and the DOV pulsating class. Previous studies of PG 1159-035 photometric data...
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...
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
Re-defining the Empirical ZZ Ceti Instability Strip (2004)
Mukadam, Anjum S., Winget, D. E., Von Hippel, Ted, Montgomery, M. H., Kepler, S. O., Costa, A. F. M.
We use the new ZZ Ceti stars (hydrogen atmosphere white dwarf variables; DAVs) discovered within the Sloan Digital Sky Survey (Mukadam et al. 2004) to re-define the empirical ZZ Ceti instability...
The Everchanging Pulsating White Dwarf GD358 (2003)
Kepler, S. O., Nather, R. E., Winget, D. E., Nitta, A., Kleinman, S. J., Metcalfe, T., ...
We report 323 hours of nearly uninterrupted time series photometric observations of the DBV star GD 358 acquired with the Whole Earth Telescope (WET) during May 23rd to June 8th, 2000. We acquired...