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Astron. Astrophys. 358, 57-64 (2000)

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Can star collisions explain the AGN variability?

G. Torricelli-Ciamponi 1,2, C. Foellmi 1,3, T.J.-L. Courvoisier 1,4 and S. Paltani 1,4

1 INTEGRAL Science Data Centre, ch. d'Ecogia 16, 1290 Versoix, Switzerland
2 Osservatorio Astrofisico di Arcetri, L.E. Fermi 5, 50125 Firenze, Italy
3 Université de Montréal,Département de physique, Montréal (Québec) H3C 3J7, Canada
4 Geneva Observatory, ch. des Maillettes 51, 1290 Versoix, Switzerland

Received 23 August 1999 / Accepted 7 March 2000


Star collisions may easily occur in a cluster of stars orbiting around a massive black hole. Such collisions can transform part of the star kinetic energy in observable radiating energy. In this paper we derive the star collision rate and the resulting highly variable luminosity for the case of a cluster containing stars of different masses. The variability of the derived light curves is computed for different sets of parameters and compared to the available data (Paltani & Courvoisier 1997). The comparison shows that the observed data trend can be reproduced by this model.

Key words: galaxies: active – galaxies: nuclei – galaxies: quasars: general – ultraviolet: galaxies

Send offprint requests to: torricel@arcetri.astro.it

© European Southern Observatory (ESO) 2000

Online publication: June 26, 2000