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HK: Hadronen und Kerne

HK 53: Nuclear Astrophysics IV

HK 53.9: Vortrag

Mittwoch, 18. März 1998, 16:15–16:30, G

New COMPTEL ²⁶Al 1.809 MeV upper limits on γ² Velorum and their implications for nucleosynthesis models of Wolf-Rayet stars — •U. Wessolowski, U. Oberlack, and R. Diehl — MPI für Extraterrestrische Physik, Giessenbachstr., D-85740 Garching

We report on new ²⁶Al 1.809 MeV upper flux limits for γ² Vel derived from nearly 5 years of mission time of the γ-ray telescope COMPTEL aboard the Compton Gamma-Ray Observatory (CGRO).
The WR+O binary system γ² Vel (WR11) is known for long to be the nearest Wolf-Rayet (W-R) star to the Sun with a recently (even more!) reduced distance of 258₋₃₁⁺⁴¹ pc by parallax measurements with the HIPPARCOS astrometric satellite [1]. Since W-R stars have been proposed as a major source of the Galactic ²⁶Al observed at 1.809 MeV this system seems to be the best candidate for a direct study of ²⁶Al yields of massive stars in the Galaxy.
We discuss the implications of our latest result on nucleosynthesis models of W-R stars (e.g. [2]) in view of the new distance of γ² Vel and the subsequent redetermination of its fundamental stellar and orbital parameters [3,4].

[1] K.A. van der Hucht, et al., NewA 2(3), 245 (1997)

[2] G. Meynet, et al., A&A 320, 460 (1997)

[3] D. Schaerer, W. Schmutz, M. Grenon, ApJ 484, L153 (1997)

[4] W. Schmutz, et al., A&A 328, 219 (1997)