Abstract

Metal Accretion on White Dwarfs Revisited

Michael Montgomery (University of Texas at Austin)

Kevin Jumper, Daniel Schulze, Don Winget (University of Texas at Austin)

Observational evidence suggests an estimated 20 to 50% of all DAs are metal polluted. At cooler temperatures, the settling times for these metals are much shorter than the evolutionary time scale, implying these stars must be actively accreting material; using theoretically computed gravitational settling times, accretion rates can be estimated. As originally pointed out by Vauclair (2004), this analysis leaves out the important process of thermohaline mixing in which a high-mu material (metals) overlies a low-mu material (hydrogen). In this talk, we study the enhancement this process has on the computed settling times and accretion rates, and we also explore the possible asteroseismic signatures this accretion could have for DAV white dwarfs.

Mode of presentation: oral