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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 ...

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 ...

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 ...

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 ...

The Giant Planet Orbiting The Cataclysmic Binary DP Leonis

Beuermann, K.; Buhlmann, J.; Diese, J.; Dreizler, S.; Hessman, F. V.; Husser, T. O.; Miller, G. F.; Nickol, N.; Pons, R.; Ruhr, D.; Schmulling, H.; Schwope, A. D.; Sorge, T.; Ulrichs, L.; Winget, D. E.; Winget, K. I. (2011-02)

Planets orbiting post-common envelope binaries provide fundamental information on planet formation and evolution, especially for the yet nearly unexplored class of circumbinary planets. We searched for such planets in DP ...

Photometric Variability In A Warm, Strongly Magnetic Dq White Dwarf, SDSS J103655.39+652252.2

Williams, Kurtis A.; Winget, D. E.; Montgomery, Michael H.; Dufour, Patrick; Kepler, S. O.; Hermes, J. J.; Falcon, Ross E.; Winget, K. I.; Bolte, Michael; Rubin, Kate H. R.; Liebert, James (2013-06)

We present the discovery of photometric variability in the DQ white dwarf SDSS J103655.39+652252.2 (SDSS J1036+6522). Time-series photometry reveals a coherent monoperiodic modulation at a period of 1115.64751(67) s with ...

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 ...

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, ...