Margarita Sharina (Special Astrophysical Observatory, Russian Academy of Sciences)
Par Stephane Charpinet - 4/12/2007
de l’Observatoire Midi-Pyrénées
(Special Astrophysical Observatory, Russian Academy of Sciences)
Vendredi 7 Décembre 2005 à 14h
OMP - Salle Coriolis
Properties of globular clusters in dwarf galaxies
Faint low surface brightness dwarf galaxies down to Mv -12 mag. have long been thought to be free of globular clusters (GCs), because they have insufficient mass for their formation. According to modern theoretical studies, massive gravitationally bound stellar clusters, possible progenitors of the present-day old GCs, born in dense, compact gas clouds in high ambient pressure environments. What is a minimum halo mass able to produce GC ? Whether properties of GCs in galaxies of different masses and morphological types are similar ? We consider evolutionary parameters of spectroscopically confirmed GCs in dwarf galaxies situated within 10 Mpc in and outside the Local Group. High-quality spectra were taken with the FORS2 instrument at the ESO’s Very Large Telescope and with the multi-slit unit of the SCORPIO spectrograph at the SAO 6m telescope. We found, that all studied GCs have low metallicity [Z/H]<1.2 dex. GCs in dwarf spheroidal galaxies are old, except KK211-3-149 (6+-2 Gyr). GCs in dwarf irregular galaxies show a large spread of ages (1-9 Gyr). Many GCs have masses 10^5 M_sun, a value proper to GC population of our own galaxy and other massive galaxies. We discuss our results in the context of the hierarchical structure formation scenario.