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Cosmic Rays from Regions of Star Formation II. The OB Associations

Published online by Cambridge University Press:  14 August 2015

M. Cassé
Affiliation:
Section d'Astrophysique Centre d'Etudes Nucléaires de Saclay, France
T. Montmerle
Affiliation:
Section d'Astrophysique Centre d'Etudes Nucléaires de Saclay, France
J. A. Paul
Affiliation:
Section d'Astrophysique Centre d'Etudes Nucléaires de Saclay, France

Extract

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Supersonic stellar winds have recently been proposed as active agents of cosmic-ray acceleration. We try to insert this potential acceleration mechanism in its general astrophysical context. Among galactic objects, OB associations have the narrowest latitude distribution, resembling to that of gamma-ray sources. Here we focus on the bulk rate of kinetic energy deposition in molecular clouds through stellar winds of individual stars pertaining to OB associations. Assuming that a minute fraction of this mechanical energy can be transferred to suprathermal particles, we examine whether OB associations are detectable high-energy gamma-ray sources, owing to the interaction of accelerated particles with the dense molecular cloud still present close to young and massive stars. The 3 factors that govern the gamma-ray “visibility” of a given OB association are i) the rate of kinetic energy deposition , where the summation is done on all mass-losing stars; is the mass-loss rate for the star i and Vi is the terminal velocity of its stellar wind;(ii) the distance of the OB association;(iii) the angular extent of the association.

Type
Research Article
Copyright
Copyright © Reidel 1981 

References

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