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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 ...

Dark Stars: Improved Models And First Pulsation Results

Rindler-Daller, T.; Montgomery, Michael H.; Freese, K.; Winget, D. E.; Paxton, B. (2015-02)

We use the stellar evolution code MESA to study dark stars (DSs). DSs, which are powered by dark matter (DM) self-annihilation rather than by nuclear fusion, may be the first stars to form in the universe. We compute stellar ...

Two Planets Orbiting The Recently Formed Post-Common Envelope Binary NN Serpentis

Beuermann, K.; Hessman, F. V.; Dreizler, S.; Marsh, T. R.; Parsons, S. G.; Winget, D. E.; Miller, G. F.; Schreiber, M. R.; Kley, W.; Dhillon, V. S.; Littlefair, S. P.; Copperwheat, C. M.; Hermes, J. J. (2010-10)

Planets orbiting post-common envelope binaries provide fundamental information on planet formation and evolution. We searched for such planets in NN Ser ab, an eclipsing short-period binary that shows long-term eclipse ...

Limits On Planets Around Pulsating White Dwarf Stars

Mullally, Fergal; Winget, D. E.; Degennaro, Steven; Jeffery, Elizabeth; Thompson, Susan E.; Chandler, Dean; Kepler, S. O. (2008-03)

We present limits on planetary companions to pulsating white dwarf stars. A subset of these stars exhibit extreme stability in the period and phase of some of their pulsation modes; a planet can be detected around such a ...

Measuring The Evolutionary Rate Of Cooling Of ZZ Ceti

Mukadam, Anjum S.; Bischoff-Kim, Agnes; Fraser, Oliver; Corsico, A. H.; Montgomery, Michael H.; Kepler, S. O.; Romero, A. D.; Winget, D. E.; Hermes, J. J.; Riecken, T. S.; Kronberg, M. E.; Winget, K. I.; Falcon, Ross E.; Chandler, Dean W.; Kuehne, J. W.; Sullivan, Denis J.; Reaves, D.; von Hippel, Ted; Mullally, Fergal; Shipman, H.; Thompson, Susan E.; Silvestri, N. M.; Hynes, Robert I. (2013-07)

We have finally measured the evolutionary rate of cooling of the pulsating hydrogen atmosphere (DA) white dwarf ZZ Ceti (Ross 548), as reflected by the drift rate of the 213.13260694 s period. Using 41 yr of time-series ...

First Unambiguous Detection of the Return of Pulsations in the Accreting White Dwarf SDSS J074531.92+453829.6 After an Outburst

Mukadam, Anjum S.; Townsley, D. M.; Szkody, P.; Gansicke, B. T.; Winget, D. E.; Hermes, J. J.; Howell, Steve B.; Teske, J.; Patterson, J.; Kemp, J.; Armstrong, Eve (2011-02)

The primary white dwarf of the cataclysmic variable SDSS J074531.92+453829.6 was discovered to exhibit non-radial pulsations in 2006 January. This accreting white dwarf underwent its first recorded dwarf nova outburst in ...

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 New ZZ Ceti White Dwarf Pulsator: G30-20

Mukadam, Anjum S.; Kepler, S. O.; Winget, D. E.; Bergeron, P. (2002-11)

We report the discovery of a new hydrogen atmosphere variable white dwarf (DAV; ZZ Ceti), G30-20, a high-amplitude, long-period pulsator. The Fourier transform of its light curve shows power around 1050-1125 s. We suspect ...

White Dwarf Luminosity And Mass Functions From Sloan Digital Sky Survey Spectra

DeGennaro, Steven; von Hippel, Ted; Winget, D. E.; Kepler, S. O.; Nitta, Atsuko; Koester, Detlev; Althaus, Leandro (2008-01)

We present the first phase in our ongoing work to use Sloan Digital Sky Survey (SDSS) data to create separate white dwarf (WD) luminosity functions (LFs) for two or more different mass ranges. In this paper, we determine ...

2006 Whole Earth Telescope Observations Of GD358: A New Look At The Prototype DBV

Provencal, J. L.; Montgomery, Michael H.; Kanaan, A.; Shipman, H. L.; Childers, D.; Baran, A.; Kepler, S. O.; Reed, M.; Zhou, A.; Eggen, J.; Watson, T. K.; Winget, D. E.; Thompson, Susan E.; Riaz, B.; Nitta, Atsuko; Kleinman, S. J.; Crowe, R.; Slivkoff, J.; Sherard, P.; Purves, N.; Binder, P.; Knight, R.; Kim, S. L.; Chen, W. P.; Yang, M.; Lin, H. C.; Lin, C. C.; Chen, C. W.; Jiang, X. J.; Sergeev, A. V.; Mkrtichian, D.; Andreev, M.; Janulis, R.; Siwak, M.; Zola, S.; Koziel, D.; Stachowski, G.; Paparo, M.; Bognar, Z.; Handler, G.; Lorenz, D.; Steininger, B.; Beck, P.; Nagel, T.; Kusterer, D.; Hoffman, A.; Reiff, E.; Kowalski, R.; Vauclair, G.; Charpinet, S.; Chevreton, M.; Solheim, J. E.; Pakstiene, E.; Fraga, L.; Dalessio, J. (2009-03)

We report on the analysis of 436.1 hr of nearly continuous high-speed photometry on the pulsating db white dwarf GD358 acquired with the Whole Earth Telescope (WET) during the 2006 international observing run, designated ...