Mass Distribution in Sloan Digital Sky Survey

Kepler Scot Kleinman, Atsuko Nitta

Detlev Koester, Bárbara Castanheira Leandro Althaus, Daniel Eisenstein, Odilon

Giovannini

1859 DAs DR4513 DR1303 PG

DR1: Madej J., Nalezyty M., Althaus L.G., 2004, A&A, 419, L5PG: 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. 2005 PG

Monte Carlo simulation for SNR=20

964 DAs

7753 DAs, 616 DBs in DR4

PGDB

DA

243 DBs g<19

High Mass DA

3230 Das with g<19, 864 (27%) have M>0.8 Mo,, 13 above 1.2Mo and Teff > 12000K

High Mass DA

Low Mass DAs

Mo

Mo

Is the increase in mass at low Teff real?

DA

-Convection bringing He up? MH<10-11M*? NO! Seismology MH>10-7

also Lawlor & McDonald 2006 models

-Neutral particles treatment? NO! Piotr Kowalski, 2006, astro-ph 0607606

-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

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=17.40WD0759+4335 17913 172 9.860 0.013 1.359 0.001 21913 419 9.51 0.07 1.314 0.012 g=18.73WD2309+0112 30017 26 8.707 0.006 1.054 0.003 30601 186 8.48 0.03 0.937 0.015 g=16.57WD0326-0011 32652 76 8.858 0.015 1.105 0.007 33202 131 8.59 0.03 0.997 0.017 g=17.65