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

2. 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

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

6. 7753 DAs in DR4, 348 in Liebert et al. 2005 PG

7. Monte Carlo simulation for SNR=20

10. 964 DAs

17. 7753 DAs, 616 DBs in DR4 PG DB DA

18. 616 DBs in DR4 and 46 in Alain Beauchamp 1995 Ph.D. Thesis PG

19. 243 DBs g<19

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

23. High Mass DA

24. Low Mass DAs MoMo MoMo

25. Is the increase in mass at low T eff real? DA -Convection bringing He up? M H 10 -7 also Lawlor & McDonald 2006 models -Neutral particles treatment? NO! Piotr Kowalski, 2006, astro-ph 0607606 -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

26. D. Koester – LPT fit to Gemini spectra – Massive DA candidates Star Teff dTeff log g dlog g SDSS auto29 Mass(Msun) WD0747+4527 14803 102 8.712 0.016 1.043 0.009 13541 149 8.77 0.03 1.073 0.017 g=17.40 WD0759+4335 17913 172 9.860 0.013 1.359 0.001 21913 419 9.51 0.07 1.314 0.012 g=18.73 WD2309+0112 30017 26 8.707 0.006 1.054 0.003 30601 186 8.48 0.03 0.937 0.015 g=16.57 WD0326-0011 32652 76 8.858 0.015 1.105 0.007 33202 131 8.59 0.03 0.997 0.017 g=17.65