NOAO >   Observing Info >   Approved Programs >   2012A-0343

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Proposal Information for 2012A-0343


PI: S.O. Kepler, Universidade Federal do Rio Grande do Sul (UFRGS), kepler@if.ufrgs.br
Address: Departamento de Astronomia - IF, Av. Bento Gon?alves, 9500, Campus do Vale, 91540-000 - Porto Alegre - RS, Brazil

CoI: Barbara Castanheira, University of Texas
CoI: Scot Kleinman, Gemini Observatory - North
CoI: Atsuko Nitta, Gemini Observatory - North
CoI: Don Winget, University of Texas
CoI: Detlev Koester, Universitet Kiel

Title: Are all high mass white dwarf stars magnetic? A test via GMOS Spectroscopy.

Abstract: We propose a pilot study 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 new white dwarf catalog from Data Release 7 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 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.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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