Search

Now showing items 1-10 of 13

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 ...

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 ...

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 ...

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, ...

Discovery Of Pulsations, Including Possible Pressure Modes, In Two New Extremely Low Mass, He-Core White Dwarfs

Hermes, J. J.; Montgomery, Michael H.; Winget, D. E.; Brown, Warren R.; Gianninas, A.; Kilic, Mukremin; Kenyon, S. J.; Bell, Keaton J.; Harrold, Samuel T. (2013-03)

We report the discovery of the second and third pulsating extremely low mass (ELM) white dwarfs (WDs), SDSS J111215.82+111745.0 (hereafter J1112) and SDSS J151826.68+065813.2 (hereafter J1518). Both have masses < 0.25 ...

Radius Constraints From High-Speed Photometry Of 20 Low-Mass White Dwarf Binaries

Hermes, J. J.; Brown, Warren R.; Kilic, Mukremin; Gianninas, A.; Chote, Paul; Sullivan, Denis J.; Winget, D. E.; Bell, Keaton J.; Falcon, Ross E.; Winget, K. I.; Mason, Paul A.; Harrold, Samuel T.; Montgomery, Michael H. (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 ...

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 ...

Discovery of an Ultramassive Pulsating White Dwarf

Hermes, J. J.; Kepler, S. O.; Castanheira, Barbara G.; Gianninas, A.; Winget, D. E.; Montgomery, M. H.; Brown, Warren R.; Harrold, Samuel T. (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 ...