26Al Emission from Massive Stars in Cygnus

Plüschke, S.; Cerviño, M.; Diehl, R.; Kretschmer, K.; Hartmann, D. H.
Referencia bibliográfica

Astronomische Gesellschaft Abstract Series, Vol. 18. Abstracts of Contributed Talks and Posters presented at the Annual Scientific Meeting of the Astronomische Gesellschaft at the Joint European and National Meeting JENAM 2001 of the European Astronomical Society and the Astronomische Gesellschaft at Munich, September 10-15, 2001, abstract #P79.

Fecha de publicación:
2001
Número de autores
5
Número de autores del IAC
0
Número de citas
0
Número de citas referidas
0
Descripción
The COMPTEL observations of the diffuse galactic 1.809 MeV emission attributed to the radioactive decay of 26Al have confirmed the diffuse nature of this interstellar emission line. One of the most significant features of the reconstructed intensity pattern is a flux enhancement in the direction of the Cygnus region. This region is fairly young and contains a wealth of massive stars, most of them grouped in the Cygnus OB associations. Multi-frequency model fitting strongly supports the hypothesis of massive stars and their descendent supernovae being the dominant sources of interstellar 26Al as observed by COMPTEL. Massive stars and supernovae are known to impart a large amount of kinetic energy into the surrounding ISM which lead to shockregions and large cavities. In addition, a large fraction of the electro-magnetic radiation of these stars lies in the extreme ultra-violet regime causing photoionisation of the surrounding interstellar medium. Based on the observed properties of the Cygnus OB associations a population synthesis model in combination with an 1D model of the expansion of superbubbles is applied to this area. In addition to the expected γ-ray line fluxes we compute the sizes and expansion parameters of the expected HI-structures and the free-free emission intensities due to the photoionizing radiation from massive stars within this region of the sky. We discuss our present understanding of the Cygnus region with respect to the massive star census. Our model assigns about 70% of the 1.809 MeV intensity to six known OB associations, about 20% to known isolated sources and roughly 10% to an unkown diffuse component.