Mass Distribution in Sloan Digital Sky Survey Kepler Scot Kleinman, Atsuko Nitta Detlev Koester, Bárbara Castanheira Leandro Althaus, Daniel Eisenstein, Odilon Giovannini

1859 DAs DR4 513 DR1 303 PG DR1: Madej J., Nalezyty M., Althaus L.G., 2004, A&A, 419, L5 PG: Liebert J., Bergeron P., Holberg J.B., 2005, ApJS, 156, 47

Why g<19? SNR>20 SDSS Gemini 8m

7753 DAs in DR4, 348 in Liebert et al PG

Monte Carlo simulation for SNR=20

964 DAs

7753 DAs, 616 DBs in DR4 PG DB DA

616 DBs in DR4 and 46 in Alain Beauchamp 1995 Ph.D. Thesis PG

243 DBs g<19

High Mass DA 3230 Das with g 0.8 M o,, 13 above 1.2M o and T eff > 12000K

High Mass DA

Low Mass DAs MoMo MoMo

Is the increase in mass at low T eff real? DA -Convection bringing He up? M H also Lawlor & McDonald 2006 models -Neutral particles treatment? NO! Piotr Kowalski, 2006, astro-ph Low metallicity in AGB? WD 1M o Lee Ann Wilson, 2000, ARA&A, 38, 573 Falk Herwig, 2004, ApJS, 155, 651 Albert Zijlstra, 2004, MNRAS, 348, L23 DA Age 12000K ~0.4 Gyr for 0.6 M o ~2 Gyr for 1.2 M o DB Age 15000K ~0.3 Gyr for 0.6 M o ~1.1Gyr for 1.2 M o -New Theory? Neutral particle broadening? DB

D. Koester – LPT fit to Gemini spectra – Massive DA candidates Star Teff dTeff log g dlog g SDSS auto29 Mass(Msun) WD g=17.40 WD g=18.73 WD g=16.57 WD g=17.65