On the evolution and fate of super-massive stars

¹ Astronomical Institute “Anton Pannekoek”, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands e-mail: lry@inasan.ru
² Institute of Astronomy of the Russian Academy of Sciences, 48 Pyatnitskaya Str., 119017 Moscow, Russia
³ Isaac Newton Institute, Moscow branch, 13 Universitetskii pr., Moscow, Russia
⁴ Armagh Observatory, College Hill, BT61 9DG, Northern Ireland, UK
⁵ Section Computational Science, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands

Received: 24 July 2007
Accepted: 4 October 2007

Abstract

Context.We study the evolution and fate of solar composition super-massive stars in the mass range 60–1000  . Our study is relevant for very massive objects observed in young stellar complexes as well as for super-massive stars that could potentially form through runaway stellar collisions.

Aims.We predict the outcomes of stellar evolution by employing a mass-loss prescription that is consistent with the observed Hertzsprung-Russell Diagram location of the most massive stars.

Methods.We compute a series of stellar models with an appropriately modified version of the Eggleton evolutionary code.

Results.We find that super-massive stars with initial masses up to 1000   end their lives as objects less massive than 150  . These objects are expected to collapse into black holes (with ) or explode as pair-instability supernovae.

Conclusions.We argue that if ultraluminous X-ray sources (ULXs) contain intermediate-mass black holes, these are unlikely to be the result of runaway stellar collisions in the cores of young clusters.