Contribution of Wolf-Rayet stars to the synthesis of 26Al
I. The -ray connection
G. Meynet 1,
M. Arnould 2,
N. Prantzos 3, 4 and
G. Paulus 2
Received 29 July 1996 / Accepted 27 August 1996
New yield predictions are derived from Wolf-Rayet (WR) model stars that are able to account better than previous ones for many important observed characteristics (like luminosities, surface chemical compositions, or number statistics) as a result of the adoption of new physical ingredients, and in particular of higher mass loss rates. The updated yields computed for WR stars with initial masses between 25 and and metallicities , 0.020, and 0.040, turn out to be about twice larger than previously reported ones.
These WR yields lead to a galactic steady state production rate of . The quoted error bar just takes into account the uncertainties in the IMF slope, the galactic metallicity gradient and the core collapse supernova rate. Thus, WR stars might account for 20 to 70% of the approximate of that are believed to be present in our Galaxy.
An even larger contamination of the Galaxy by WR stars cannot be ruled out, as it appears from an analysis of the impact on the yields of other sources of uncertainty that affect individual model stars, like the mass loss rate, the mixing procedure, and some key nuclear reaction rates. Each effect considered separately may lead to an additional uncertainty in the WR yields that amounts to a factor of about 2 to 3.
Key words: stars: Wolf-Rayet gamma-rays: theory nucleosynthesis, abundances
Send offprint requests to: G. Meynet
© European Southern Observatory (ESO) 1997
Online publication: June 30, 1998