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Mass Distribution in Sloan Digital Sky Survey. Kepler Scot Kleinman, Atsuko Nitta Detlev Koester, B árbara 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
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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 Gemini 8m SDSS
DA DB PG 7753 DAs, 616 DBs in DR4
High Mass DA 3230 Das with g<19, 864 (27%) have M>0.8 Mo,, 13 above 1.2Mo and Teff > 12000K
Low Mass DAs Mo Mo
Is the increase in mass at low Teff real? -Convection bringing He up? MH<10-11M*? NO! Seismology MH>10-7 alsoLawlor & McDonald 2006 models -Neutral particles treatment? NO! Piotr Kowalski, 2006, astro-ph0607606 -Low metallicity in AGB? WD 1Mo Lee Ann Wilson, 2000, ARA&A, 38, 573 Falk Herwig, 2004, ApJS, 155, 651 Albert Zijlstra, 2004, MNRAS, 348, L23 DA Age12000K ~0.4 Gyr for 0.6 Mo ~2 Gyr for 1.2 Mo DB Age15000K ~0.3 Gyr for 0.6 Mo ~1.1Gyr for 1.2 Mo -New Theory? Neutral particle broadening? DB DA
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