Collisions between single stars in dense clusters: Runaway formation of a massive object

Freitag M., Guerkan M. A., Rasio F. A.

Workshop on Massive Stars in Interacting Binaries, Mauricie, Kanada, 16 - 20 Ağustos 2004, cilt.367, ss.707-709 identifier

  • Yayın Türü: Bildiri / Tam Metin Bildiri
  • Cilt numarası: 367
  • Basıldığı Şehir: Mauricie
  • Basıldığı Ülke: Kanada
  • Sayfa Sayıları: ss.707-709
  • Orta Doğu Teknik Üniversitesi Adresli: Hayır

Özet

Using Monte Carlo codes, we follow the collisional evolution of clusters in a variety of scenarios. We consider the conditions under which a cluster of main-sequence stars may undergo rapid core collapse due to mass segregation, thus entering a phase of runaway collisions, forming a very massive star (VMS, M-* > 1000M(circle dot)) through repeated collisions between single stars. Although collisional mass loss is accounted for realistically, we find that a VMS forms even in proto-galactic nuclei models with a high velocity dispersion (many 100 km s(-1)). Such a VMS may be a progenitor for an intermediate-mass black hole (M-center dot >= 100 M-circle dot). In contrast, in galactic nuclei hosting a central massive black hole, collisions are found to be disruptive. The stars which are subject to collisions are progressively ground down by high-velocity collisions and a merger sequence appears impossible.