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A New Timescale For Period Change In The Pulsating DA White Dwarf WD 0111+0018

Hermes, J. J.; Montgomery, Michael H.; Mullally, Fergal; Winget, D. E.; Bischoff-Kim, Agnes (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 ...

Two New Tidally Distorted White Dwarfs

Hermes, J. J.; Kilic, Mukremin; Brown, Warren R.; Montgomery, Michael H.; Winget, D. E. (2012-04)

We identify two new tidally distorted white dwarfs (WDs), SDSS J174140.49+652638.7 and J211921.96-001825.8 (hereafter J1741 and J2119). Both stars are extremely low mass (ELM, <= 0.2 M-circle dot)WDs in short-period, ...

Precision Asteroseismology Of The Pulsating White Dwarf Gd 1212 Using A Two-Wheel-Controlled Kepler Spacecraft

Hermes, J. J.; Charpinet, S.; Barclay, Thomas; Pakstiene, E.; Mullally, Fergal; Kawaler, Steven D.; Bloemen, S.; Castanheira, Barbara G.; Winget, D. E.; Montgomery, Michael H.; Van Grootel, V.; Huber, Daniel; Still, Martin; Howell, Steve B.; Caldwell, Douglas A.; Haas, Michael R.; Bryson, Stephen T. (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 ...

A Gravitational Redshift Determination Of The Mean Mass Of White Dwarfs. DA Stars

Falcon, Ross E.; Winget, D. E.; Montgomery, Michael H.; Williams, Kurtis A. (2010-03)

We measure apparent velocities (v(app)) of the H alpha and H beta Balmer line cores for 449 non-binary thin disk normal DA white dwarfs (WDs) using optical spectra taken for the European Southern Observatory SN Ia progenitor ...

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 ...

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, ...

A Gravitational Redshift Determination Of The Mean Mass Of White Dwarfs: DBA And DB Stars

Falcon, Ross E.; Winget, D. E.; Montgomery, Michael H.; Williams, Kurtis A. (2012-10)

We measure apparent velocities (nu(app)) of absorption lines for 36 white dwarfs (WDs) with helium-dominated atmospheres-16 dbAs and 20 dbs-using optical spectra taken for the European Southern Observatory SN Ia progenitor ...