Second parameter globulars and dwarf spheroidals around the Local Group massive galaxies: What can they evidence?

Sternberg Astronomical Institute, University Avenue 13, 119899 Moscow, Russia

Corresponding author: scorpi@sai.msu.ru

Received: 29 April 2002
Accepted: 28 August 2002

Abstract

We suggest that the majority of the “young”, so–called “second parameter” globular clusters (SPGCs) have originated in the outer Galactic halo due to a process other than a tidal disruption of the dwarf spheroidal (dSph) galaxies. Basic observational evidence regarding both the dSphs and the SPGCs, coupled with the latest data about a rather large relative number of such clusters among globulars in M 33 and their low portion in M 31, seems to be consistent with the suspected process. It might have taken place within the system of the most massive galaxies of the Local Group (LG) at the earliest stages of their formation and evolution. We argue that the origin and basic characteristics of the SPGCs can naturally be explained as a result of mass outflow from M 31, during and due to formation of its Pop. II stars, and subsequent accretion of gas onto its massive companions, the Galaxy and M 33. An amount of the gas accreted onto the Milky Way is expected to have been quite enough for the formation in the outer Galactic halo not only of the clusters under consideration but also a number of those dSph galaxies which are as young as the SPGCs. A less significant, but notable mass transfer from the starbursting protoGalaxy to the massive members of the LG might have occurred, too.