Faint stars in the Ursa Minor dwarf spheroidal galaxy: implications for the low-mass stellar initial mass function at high redshift

RFG Wyse, G Gilmore, ML Houdashelt, Sofia Feltzing, L Hebb, JS Gallagher, TA Smecker-Hane

Research output: Contribution to journalArticlepeer-review

52 Citations (SciVal)

Abstract

The stellar initial mass function at high redshift is an important defining property of the first stellar systems to form and may also play a role in various dark matter problems. We here determine the faint stellar luminosity function in an apparently dark-matter-dominated external galaxy in which the stars formed at high redshift. The Ursa Minor dwarf spheroidal galaxy is a system with a particularly simple stellar population-all of the stars being old and metal-poor-similar to that of a classical halo globular cluster. A direct comparison of the faint luminosity functions of the UMi dSph and of similar metallicity, old globular clusters is equivalent to a comparison of the initial mass functions and is presented here, based on deep HST WFPC2 and STIS imaging data. We find that these luminosity functions are indistinguishable, down to a luminosity corresponding to similar to0.3 M-.. Our results show that the low-mass stellar IMF for stars that formed at very high redshift is apparently invariant across environments as diverse as those of an extremely low-surface-brightness, dark-matter-dominated dwarf galaxy and a dark-matter-free, high-density globular cluster within the Milky Way.
Original languageEnglish
Pages (from-to)395-433
JournalNew Astronomy
Volume7
Issue number7
DOIs
Publication statusPublished - 2002

Subject classification (UKÄ)

  • Astronomy, Astrophysics and Cosmology

Keywords

  • individual : Ursa Minor
  • mass function
  • stars : luminosity function
  • dark matter
  • galaxies : stellar content
  • kinematics and dynamics
  • galaxies :

Fingerprint

Dive into the research topics of 'Faint stars in the Ursa Minor dwarf spheroidal galaxy: implications for the low-mass stellar initial mass function at high redshift'. Together they form a unique fingerprint.

Cite this