EDP Sciences
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Volume 417, Number 2, April II 2004
Page(s) 437 - 442
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20034368

A&A 417, 437-442 (2004)
DOI: 10.1051/0004-6361:20034368

Formation of giant globular cluster G1 and the origin of the M 31 stellar halo

K. Bekki1 and M. Chiba2

1  School of Physics, University of New South Wales, Sydney 2052, Australia
2  Astronomical Institute, Tohoku University, Sendai, 980-8578, Japan
    e-mail: chiba@astr.tohoku.ac.jp

(Received 20 September 2003 / Accepted 21 October 2003)

We demonstrate that globular cluster G1 could have been formed by tidal interaction between M 31 and a nucleated dwarf galaxy (dE,N). Our fully self-consistent numerical simulations show that during tidal interaction between M 31 and G1's progenitor dE,N with $M_{B} \sim -15$ mag and its nucleus mass of ~ 107 $M_{\odot}$, the dark matter and the outer stellar envelope of the dE,N are nearly completely stripped whereas the nucleus can survive the tidal stripping because of its initially compact nature. The naked nucleus (i.e., G1) has orbital properties similar to those of its progenitor dE,N. The stripped stars form a metal-poor ([Fe/H] ~ -1) stellar halo around M 31 and its structure and kinematics depend strongly on the initial orbit of G1's progenitor dE,N. We suggest that the observed large projected distance of G1 from M 31 (~40 kpc) can give some strong constraints on the central density of the dark matter halo of dE,N. We discuss these results in the context of substructures of M 31's stellar halo recently revealed by Ferguson et al. (2002).

Key words: galaxies: halos -- galaxies: individual: M 31 -- galaxies: interactions -- galaxies: star clusters -- Galaxy: globular clusters: individual: $\omega$ Centauri -- Galaxy: globular clusters: individual: Mayall II = G1

Offprint request: K. Bekki, bekki@bat.phys.unsw.edu.au

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