A Relic Star Cluster in the Sextans Dwarf Spheroidal Galaxy: Implications for Early Star and Galaxy Formation
2012 (English)In: Conference on the Galactic Archaeology: Near-Field Cosmology and the Formation of the Milky Way, SAN FRANCISCO, 2012, Vol. 458, 257-260 p.Conference paper (Other academic)
We present tentative evidence for the existence of a dissolved star cluster in the Sextans dwarf spheroidal galaxy. In a sample of six stars, we identify three (possibly four) stars around [Fe/H] = -2.7 that are highly clustered in a multi-dimensional chemical abundance space. The estimated initial stellar mass of the cluster is M-*,(init) = 1.9(-0.9)(+1.5) (1.6(-0.8)(+1.2)) x 10(5) M-circle dot assuming a Salpeter (Kroupa) initial mass function (IMF). If corroborated by follow-up spectroscopy, this ancient star cluster at [Fe/H] = -2.7 is the most metal-poor system identified to date. Inspired by this finding, we also present a new way to interpret the cumulative metallicity functions of dwarf galaxies. From available observational data, we speculate that the ultra-faint dwarf galaxy population, or a significant fraction thereof, and the more luminous, classical dwarf spheroidal population were formed in different environments and would thus be distinct in origin.
Place, publisher, year, edition, pages
SAN FRANCISCO, 2012. Vol. 458, 257-260 p.
, Astronomical Society of the Pacific Conference Series, 458
IdentifiersURN: urn:nbn:se:uu:diva-185678ISI: 000309700000076ISBN: 978-1-58381-798-8OAI: oai:DiVA.org:uu-185678DiVA: diva2:572373
The 3rd Subaru International Conference: Galactic Archaeology - Near-Field Cosmology and the Formation of the Milky Way, nov 01-04, 2011, Shezenji, JAPAN