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A Relic Star Cluster in the Sextans Dwarf Spheroidal Galaxy - Implications for Early Star and Galaxy Formation
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
2012 (English)In: Galactic Archaeology: Near-Field Cosmology and the Formation of the Milky Way, 2012, Vol. 458Conference paper (Refereed)
##### Abstract [en]

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$^+1.5$$_-0.9 (1.6^+1.2$$_-0.8$)\times 10$^5$ M$_&sun;$ 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.

2012. Vol. 458
##### Series
, Astronomical Society of the Pacific Conference Series
##### National Category
Astronomy, Astrophysics and Cosmology
##### Identifiers
OAI: oai:DiVA.org:uu-196839DiVA: diva2:610956
##### Conference
Astronomical Society of the Pacific Conference
Available from: 2013-03-13 Created: 2013-03-13 Last updated: 2013-03-13

#### Open Access in DiVA

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##### By organisation
Theoretical Astrophysics
##### On the subject
Astronomy, Astrophysics and Cosmology