An amplitude limitation mechanism for pulsating white dwarfs

M. H. MONTGOMERY; A. D. ROMERO; A. H. CÓRSICO

Montreal

Workshop; 19th European White Dwarf Workshop; 2014

The mass of the convection zone in models of pulsating white dwarfsis a sensitive function of the instantaneous surface temperature; this mass can varyby up to a factor of 10 between the minimum and maximum temperature variations.Due to this sensitivity, the outer turning point for finite-amplitude g-mode pulsationsvaries depending upon the local surface temperature, producing a reflected wave thatis slightly out of phase with that required for complete constructive interference. Aftermany reflections, this leads to a reduction in the global amplitude of the mode. Forgiven amplitudes, we compare the size of this damping rate with typical growth ratesfound in models of DAVs. This could be an important effect for stars near the red edgeof the DAV instability strip.