Search

Now showing items 31-40 of 42

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). ...

A 12 Minute Orbital Period Detached White Dwarf Eclipsing Binary

Brown, Warren R.; Kilic, Mukremin; Hermes, J. J.; Prieto, Carlos Allende; Kenyon, Scott J.; Winget, D. E. (2011-08)

We have discovered a detached pair of white dwarfs (WDs) with a 12.75 minute orbital period and a 1315 km s(-1) radial velocity amplitude. We measure the full orbital parameters of the system using its light curve, which ...

The ZZ Ceti Red Edge

Kanaan, A.; Kepler, S. O.; Winget, D. E. (2002-06)

With a time-series CCD photometric survey, we have demonstrated clearly that the observed red edge for the ZZ Ceti stars instability strip at 11 000 K is real, with the pulsation amplitude decreasing at least by a factor ...

Fine Grid Asteroseismology Of G117-B15A And R548

Bischoff-Kim, Agnes; Montgomery, Michael H.; Winget, D. E. (2008-03)

We now have a good measurement of the cooling rate of G117-B15A. In the near future, we will have equally well determined cooling rates for other pulsating white dwarfs, including R548. The ability to measure their cooling ...

Evidence For Temperature Change And Oblique Pulsation From Light Curve Fits Of The Pulsating White Dwarf GD 358

Montgomery, Michael H.; Provencal, J. L.; Kanaan, A.; Mukadam, Anjum S.; Thompson, Susan E.; Dalessio, J.; Shipman, H. L.; Winget, D. E.; Kepler, S. O.; Koester, Detlev (2010-06)

Convective driving, the mechanism originally proposed by Brickhill for pulsating white dwarf stars, has gained general acceptance as the generic linear instability mechanism in DAV and dbV white dwarfs. This physical ...

A Dark Spot On A Massive White Dwarf

Kilic, Mukremin; Gianninas, Alexandros; Bell, Keaton J.; Curd, Brandon; Brown, Warren R.; Hermes, J. J.; Dufour, P.; Wisniewski, J. Patrick; Winget, D. E.; Winget, K. I. (2015-12)

We present the serendipitous discovery of eclipse-like events around the massive white dwarf SDSS J152934.98+292801.9 (hereafter J1529+2928). We selected J1529+2928 for time-series photometry based on its spectroscopic ...

HST And Optical Data Reveal White Dwarf Cooling, Spin, And Periodicities In GW Librae 3-4 Years After Outburst

Szkody, Paula; Mukadam, Anjum S.; Gansicke, Boris T.; Henden, Arne; Sion, Edward M.; Townsley, Dean; Chote, Paul; Harmer, Diane; Harpe, Eric J.; Hermes, J. J.; Sullivan, Denis J.; Winget, D. E. (2012-07)

Since the large amplitude 2007 outburstwhich heated its accreting, pulsatingwhite dwarf, the dwarf nova system GW Librae has been cooling to its quiescent temperature. Our Hubble Space Telescope ultraviolet spectra combined ...

SDSS J184037.78+642312.3: the First Pulsating Extremely Low Mass White Dwarf

Hermes, J. J.; Montgomery, M. H.; Winget, D. E.; Brown, Warren R.; Kilic, Mukremin; Kenyon, Scott J. (2012-05)

We report the discovery of the first pulsating extremely low mass (ELM) white dwarf (WD), SDSS J184037.78+642312.3 (hereafter J1840). This DA (hydrogen-atmosphere) WD is by far the coolest and the lowest-mass pulsating WD, ...

The Pulsation Modes Of The Pre-White Dwarf PG 1159-035

Costa, J. E. S.; Kepler, S. O.; Winget, D. E.; O'Brien, M. S.; Kawaler, S. D.; Costa, A. F. M.; Giovannini, O.; Kanaan, A.; Mukadam, A. S.; Mullally, F.; Nitta, A.; Provencal, J. L.; Shipman, H.; Wood, M. A.; Ahrens, T. J.; Grauer, A.; Kilic, M.; Bradley, P. A.; Sekiguchi, K.; Crowe, R.; Jiang, X. J.; Sullivan, D.; Sullivan, T.; Rosen, R.; Clemens, J. Christopher; Janulis, R.; O'Donoghue, D.; Ogloza, W.; Baran, A.; Silvotti, R.; Marinoni, S.; Vauclair, G.; Dolez, N.; Chevreton, M.; Dreizler, S.; Schuh, S.; Deetjen, J.; Nagel, T.; Solheim, J. E.; Perez, J. M. G.; Ulla, A.; Barstow, M.; Burleigh, M.; Good, S.; Metcalfe, T. S.; Kim, S. L.; Lee, H.; Sergeev, A.; Akan, M. C.; Cakirli, O.; Paparo, M.; Viraghalmy, G.; Ashoka, B. N.; Handler, G.; Hurkal, O.; Johannessen, F.; Kleinman, S. J.; Kalytis, R.; Krzesinski, J.; Klumpe, E.; Larrison, J.; Lawrence, T.; Meistas, E.; Martinez, P.; Nather, R. E.; Fu, J. N.; Pakstiene, E.; Rosen, R.; Romero-Colmenero, E.; Riddle, R.; Seetha, S.; Silvestri, N. M.; Vuckovic, M.; Warner, B.; Zolao, S.; Althaus, L. G.; Corsico, A. H.; Montgomery, M. H. (2008-01)

Context. PG 1159-035, a pre-white dwarf with T-eff similar or equal to 140000 K, is the prototype of both two classes: the PG 1159 spectroscopic class and the DOV pulsating class. Previous studies of PG 1159-035 photometric ...