August 11-15, 2014


On the origin of hydrogen in DB white dwarfs

Pierre Bergeron (Université de Montréal)

Benoit Rolland, Marie-Michèle Limoges, Noemi Giammichele, Loïc Séguin-Charbonneau (Université de Montréal)

Elizabeth M. Green (Steward Observatory, University of Arizona)

We report new spectroscopic observations of DB white dwarfs near the region of Halpha aimed at better constraining the hydrogen abundance in the photosphere of these stars. These spectroscopic data are analyzed with model atmosphere techniques and combined with our previously published results in order to provide an improved picture of the hydrogen abundances in DBA stars - or upper limits in DB’s - as a function of effective temperature. The origin of hydrogen in DB white dwarfs is discussed in terms of the two most likely scenarios, a residual origin from convective mixing or accretion from the interstellar medium.

Mode of presentation: poster