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Measuring The Evolutionary Rate Of Cooling Of ZZ Ceti
(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 ...
A New Timescale For Period Change In The Pulsating DA White Dwarf WD 0111+0018
(2013-03)
We report the most rapid rate of period change measured to date for a pulsating DA (hydrogen atmosphere) white dwarf (WD), observed in the 292.9 s mode of WD0111+0018. The observed period change, faster than 10(-12) s ...
Limits Of Perturbative Nonlinear Light Curve Analyses: The Case Of G117-B15A
(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 ...
Radius Constraints From High-Speed Photometry Of 20 Low-Mass White Dwarf Binaries
(2014-09)
We carry out high-speed photometry on 20 of the shortest-period, detached white dwarf binaries known and discover systems with eclipses, ellipsoidal variations (due to tidal deformations of the visible white dwarf), and ...
Precision Asteroseismology Of The Pulsating White Dwarf Gd 1212 Using A Two-Wheel-Controlled Kepler Spacecraft
(2014-07)
We present a preliminary analysis of the cool pulsating white dwarf (WD) GD 1212, enabled by more than 11.5 days of space-based photometry obtained during an engineering test of the two-reaction-wheel-controlled Kepler ...
Discovery of an Ultramassive Pulsating White Dwarf
(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
(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 ...
SDSS J184037.78+642312.3: the First Pulsating Extremely Low Mass White Dwarf
(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, ...