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The Physics of Crystallization from Globular Cluster White Dwarf Stars in NGC 6397

Winget, D. E.; Kepler, S. O.; Campos, Fabiola; Montgomery, M. H.; Girardi, Leo; Bergeron, P.; Williams, Kurtis (2009-03)

We explore the physics of crystallization in the deep interiors of white dwarf (WD) stars using the color-magnitude diagram and luminosity function constructed from proper- motion cleaned Hubble Space Telescope photometry ...

SDSS J142625.71+575218.3: A Prototype for A New Class of Variable White Dwarf

Montgomery, M. H.; Williams, Kurtis A.; Winget, D. E.; Dufour, Patrick; DeGennaro, Steven; Liebert, James (2008-05)

We present the results of a search for pulsations in six of the recently discovered carbon-atmosphere white dwarf ("hot DQ") stars. On the basis of our theoretical calculations, the star SDSS J142625.71 + 575218.3 is the ...

A Status Report On A Planet Search Around White Dwarf Stars

Hermes, J. J.; Mullally, F.; Winget, D. E.; Montgomery, M. H.; Miller, G. F.; Ellis, J. L. (2010-08)

We have continued monitoring a pilot sample of 15 isolated, pulsating DA white dwarfs for center-of-mass motion caused by a planetary companion. Roughly 7 years into our survey, we have preliminary evidence for periodic ...

Limits Of Perturbative Nonlinear Light Curve Analyses: The Case Of G117-B15A

Montgomery, M. H.; Hermes, J. J.; Winget, D. E. (2010-08)

This poster examines the nonlinear combination frequencies found in the DAV G117-B15A. Using multiple epochs of observations we show that the ratio of the amplitude of the combination frequencies to those of the parent ...

Enigmatic Recurrent Pulsational Variability Of The Accreting White Dwarf EQ LYN (Sdss J074531.92+453829.6)

Mukadam, Adam S.; Townsley, D. M.; Szkody, Paula; Gaansicke, B. T.; Southworth, J.; Brockett, T.; Parsons, S.; Hermes, J. J.; Montgomery, M. H.; Winget, D. E.; Harrold, S.; Tovmassian, G.; Zharikov, S.; Drake, A. J.; Henden, A.; Rodriguez-Gil, P.; Sion, E. M.; Zola, S.; Szymanski, T.; Pavlenko, E.; Aungwerojwit, A.; Qian, S. B. (2013-09)

Photometric observations of the cataclysmic variable EQ Lyn (SDSS J074531.92+453829.6), acquired from 2005 October to 2006 January, revealed high-amplitude variability in the range 1166-1290 s. This accreting white dwarf ...

A Gravitational Redshift Determination Of The Mean Mass Of DBA White Dwarfs

Falcon, R. E.; Winget, D. E.; Montgomery, M. H.; Williams, K. A. (2010-08)

We measure apparent velocities (v(app)) of the H alpha and H beta Balmer line cores for 16 helium-dominated white dwarfs (WDs) using optical spectra taken for the European Southern Observatory SN Ia progenitor survey (SPY). ...

White Dwarfs In Ngc6397 And M4: Constraints On The Physics Of Crystallization

Winget, D. E.; Montgomery, M. H.; Kepler, S. O.; Campos, F.; Bergeron, P. (2010-08)

We explore the physics of crystallization in the dense Coulomb plasma of the deep interiors of white dwarf stars using the color-magnitude diagram and luminosity function constructed from Hubble Space Telescope photometry ...

Discovery of an Ultramassive Pulsating White Dwarf

Hermes, J. J.; Kepler, S. O.; Castanheira, Barbara G.; Gianninas, A.; Winget, D. E.; Montgomery, M. H.; Brown, Warren R.; Harrold, Samuel T. (2013-07)

We announce the discovery of the most massive pulsating hydrogen-atmosphere white dwarf (WD) ever discovered, GD 518. Model atmosphere fits to the optical spectrum of this star show it is a 12,030 +/- 210 K WD with a log ...

A Second Case of Outbursts in A Pulsating White Dwarf Observed By Kepler

Hermes, J. J.; Montgomery, M. H.; Bell, Keaton J.; Chote, P.; Gansicke, B. T.; Kawaler, Steven D.; Clemens, J. Christopher; Dunlap, B. H.; Winget, D. E.; Armstrong, D. J. (2015-09)

We present observations of a new phenomenon in pulsating white dwarf stars: large-amplitude outbursts at timescales much longer than the pulsation periods. The cool (T-eff = 11,060 K), hydrogen-atmosphere pulsating white ...

Creating White Dwarf Photospheres In The Laboratory

Falcon, R. E.; Rochau, G. A.; Bailey, J. E.; Ellis, J. L.; Montgomery, M. H.; Winget, D. E.; Gomez, M. R.; Leeper, R. J. (2010-08)

We present a preliminary report from the laboratory astrophysics experiments to create macroscopic (similar to 19 cm(3)) hydrogen-plasmas with white dwarf (WD) photospheric conditions (i.e., temperature, electron density). ...