The nature of the density clump in the fornax dwarf spheroidal galaxy

Edward W. Olszewski, Mario Mateo, Jason Harris, Matthew G. Walker, Matthew G. Coleman, G. S.D.A. Costa

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


We have imaged the recently discovered stellar overdensity located approximately one core radius from the center of the Fornax dwarf spheroidal galaxy using the Magellan Clay 6.5 m telescope with the Magellan Instant Camera. Superb seeing conditions allowed us to probe the stellar populations of this overdensity and of a control field within Fornax to a limiting magnitude of R = 26. The color-magnitude diagram of the overdensity field is virtually identical to that of the control field, with the exception of the presence of a population arising from a very short (less than 300 Myr in duration) burst of star formation 1.4 Gyr ago. Coleman et al. have argued that this overdensity might be related to a shell structure in Fornax that was created when Fornax captured a smaller galaxy. Our results are consistent with this model, but we argue that the metallicity of this young component favors a scenario in which the gas was part of Fornax itself.

Original languageEnglish (US)
Pages (from-to)912-921
Number of pages10
JournalAstronomical Journal
Issue number2
StatePublished - Feb 2006


  • Galaxies: dwarf
  • Galaxies: individual (Fornax dSph)
  • Galaxies: stellar content - Local Group Online material: Machine-readable tables

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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