Astronomy and Astrophysics – Astrophysics
Scientific paper
2003-09-17
Astrophys.J.600:1025-1034,2004
Astronomy and Astrophysics
Astrophysics
31 pages, 11 figures. Accepted by ApJ
Scientific paper
10.1086/380090
H3+ has been shown (Lenzuni et al. 1991, ApJS, 76, 759) to be the dominant positive ion, in a zero metallicity gas at low temperature and intermediate to high density. It therefore affects both the number of free electrons and the opacity of the gas. The most recent H3+ partition function (Neale and Tennyson, 1995, ApJ, 454, L169) is an order of magnitude larger at 4000 K than all previous partition functions, implying that H3+ is a more important electron donor than previously thought. Here we present new Rosseland mean opacities for a hydrogen-helium gas of 1000 < T(K) < 9000 and -14 < log10(density [g/cc]) < -2. In the calculation of these opacities we have made use of the latest collision induced absorption data as well as the most recent H3+ partition function and line opacity data. It is shown that these updated and new sources of opacity give rise to a Rosseland mean opacity for a hydrogen-helium gas which is in general greater than that calculated in earlier works. The new opacity data are then used to model the evolution of low mass 0.15-0.8 Mo zero metallicity stars, from pre-Main Sequence collapse to Main Sequence turn-off. To investigate the effect of H3+ on the evolution of low mass zero metallicity stars, we repeat our calculations neglecting H3+ as a source of electrons and line opacity. We find that H3+ can have an effect on the structure and evolution of stars of mass ~0.5 Mo or less. A gray atmosphere is used for the calculation, which is sufficient to demonstrate that H3+ affects the evolution of very low mass stars to a greater degree than previously believed.
Harris Gregory J.
Lynas-Gray Anthony E.
Miller Samantha
Tennyson Jonathan
No associations
LandOfFree
The effect of the electron donor H3+ on the pre-main and Main Sequence evolution of low mass zero metallicity stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The effect of the electron donor H3+ on the pre-main and Main Sequence evolution of low mass zero metallicity stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The effect of the electron donor H3+ on the pre-main and Main Sequence evolution of low mass zero metallicity stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-137018