Open AccessA‐star envelopes: a test of local and non‐local models of convection
Author(s) -
Kupka F.,
Montgomery M. H.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05268.x
Subject(s) - physics , convection , stars , astrophysics , thermal , convection zone , mixing (physics) , star (game theory) , mechanics , meteorology , quantum mechanics
We present results of a fully non‐local, compressible model of convection for A‐star envelopes. This model quite naturally reproduces a variety of results from observations and numerical simulations which local models based on a mixing length do not. Our principal results, which are for models with T eff between 7200 and 8500 K, are the following. First, the photospheric velocities and filling factors are in qualitative agreement with those derived from observations of line profiles of A‐type stars. Secondly, the He ii and H i convection zones are separated in terms of convective flux and thermal interaction, but joined in terms of the convective velocity field, in agreement with numerical simulations. In addition, we attempt to quantify the amount of overshooting in our models at the base of the He ii convection zone.