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Application of improved model spectra to DA white dwarfs in the SDSS

Application of improved model spectra to DA white dwarfs in the SDSS. Pier-Emmanuel Tremblay & Pierre Bergeron Université de Montréal. Tremblay & Bergeron (2009). log g = 7 , log g = 9. +0.03 M . Spectroscopic technique Bergeron et al. (1992). Tremblay et al. (2010).

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Application of improved model spectra to DA white dwarfs in the SDSS

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  1. Application of improved model spectra to DA white dwarfs in the SDSS Pier-Emmanuel Tremblay & Pierre BergeronUniversité de Montréal

  2. Tremblay & Bergeron (2009) log g = 7,log g = 9 +0.03 M Spectroscopic technique Bergeron et al. (1992)

  3. Tremblay et al. (2010) 10 minutes ago : Gianninas et al. sample He/H = 0.25 He/H = 0.0

  4. Keck Telescope(2009)

  5. SDSS (DR4) Eisenstein et al. (2006) Kepler et al. (2007) DA DB In this work:-improved models -alternative fitting method -DR7 reduction -visual inspection (S/N > 12)

  6. SDSS DR4 8817 stars Kepler et al. (2007) g < 19 S/N > 30 ~800 stars

  7. ~800 stars per bin, all subtypes removed

  8. 40,000 K > Teff > 13,000 K DR4 sample Same models, same method

  9. Equivalent Width of Balmer Lines SDSS Gianninas et al. Hβ Hγ Hδ

  10. T spec vs. T phot (%) DA+DB (or DC) problematic data

  11. DA+DA DA+DB(DC)[6000-40,000 K]

  12. S/N > 12 • 9 DA+DB Only 1 analyzed previously (Limoges et al.) More DB+DA (DBA)

  13. 1 DA+DB or DAB

  14. 25 DA+DC candidates • At low S/N, we can’t rule out: • (9) weakly magnetic • (8) He-rich DA DC

  15. Conclusions SDSS DR4 – Improved models • Homogeneous sample, S/N > 15 for mass distribution. • <M/M> = 0.61 • Mean mass of DA not clear : data reduction effects? • Good sample to study high log g problem. • 35 DA+DB(DC) stars.

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