DG.8.04 — Are All Magnetic White Dwarf Stars Massive?

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Aug 10th at 5:10 PM until 5:30 PM

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Author(s): Atsuko Nitta1, S.O. Kepler3, Baybars Kulebi4, D. Koester5, S. Kleinman1, D.E. Winget6, Barbara G. Castanheira6, Alejandro H. Corsico2

Institution(s): 1. Gemini Observatory, 2. Universidad Nacional de La Plata, 3. Universidade Federal do Rio Grande do Sul, 4. Universitat Heidelberg, 5. Universitat Kiel, 6. University of Texas at Austin

Our goal is to address the mystery of the origin of magnetic fields in white dwarf stars. One telling clue in this mystery is that spectroscopic mass determinations for magnetic white dwarf stars are consistently higher (averaging ~0.93Msun) than for non-magnetic white dwarf stars (approximately 0.6Msun). Through our white dwarf catalog of the Sloan Digital Sky Survey (SDSS), we have, for the first time ever, a statistically significant estimate of the distribution of over 1000 magnetic white dwarf stars of different field strengths versus mass and temperature. The low S/N SDSS spectra, however, leave some uncertainty in our identifications of magnetic fields and hamper our ability to simultaneously measure both the Zeeman-splitting and the Stark pressure broadening in these stars, meaning we cannot reliably measure both B and log(g). Obtaining S/N>70 spectra at Gemini for a sample of low field massive magnetic white dwarf stars, we will test our low S/N determinations of magnetic fields, search for ways to measure B and log(g) simultaneously, and ultimately determine if these magnetic fields are likely developed through the star's own surface convection zone, or inherited from massive Ap/Bp progenitors.