TY - JOUR
T1 - A new study of stellar substructures in the Fornax dwarf spheroidal galaxy
AU - De Boer, T. J.L.
AU - Tolstoy, E.
AU - Saha, A.
AU - Olszewski, E. W.
N1 - Funding Information:
The National Optical Astronomy Observatory is operated by AURA, Inc., under cooperative agreement with the National Science Foundation.
Funding Information:
The authors thank ISSI (Bern) for support of the team “Defining the full life-cycle of dwarf galaxy evolution: the Local Universe as a template”. T.d.B and E.T. gratefully acknowledge the Netherlands Foundation for Scientific Research (NWO) for financial support through a VICI grant. E.O. is partially supported by NSF grant AST0807498. The authors would like to thank the anonymous referee for his/her comments, that helped to improve the paper.
PY - 2013
Y1 - 2013
N2 - Using deep V,B - V wide-field photometry, we have conducted a new study of stellar over-densities in the Fornax dwarf spheroidal galaxy by determining detailed star formation histories from colour-magnitude diagram analysis. We have concentrated on the relatively young stellar component (<4 Gyr old), and compared this to the underlying Fornax field population. We have studied in more detail the previously known inner shell-like structure and shown that it has a well-defined age-metallicity relation with a peak at ≈1.5 Gyr, [Fe/H] = -0.6 dex. Comparison to the Fornax centre shows that the over-dense feature is consistent with the age-metallicity relation of young field stars, and likely formed from Fornax gas. This is consistent with a scenario in which the over-density was formed by the re-accretion of previously expelled gas. We have also discovered a new stellar over-density, located 0.3 degrees (0.7 kpc) from the centre, which is only 100 Myr old, with solar metallicity. This feature constitutes some of the youngest, most metal-rich stars stars observed in Fornax to date. It is unclear how the young over-density was formed, although the age and metallicity of stars suggest this feature may represent the last star formation activity of the Fornax dSph.
AB - Using deep V,B - V wide-field photometry, we have conducted a new study of stellar over-densities in the Fornax dwarf spheroidal galaxy by determining detailed star formation histories from colour-magnitude diagram analysis. We have concentrated on the relatively young stellar component (<4 Gyr old), and compared this to the underlying Fornax field population. We have studied in more detail the previously known inner shell-like structure and shown that it has a well-defined age-metallicity relation with a peak at ≈1.5 Gyr, [Fe/H] = -0.6 dex. Comparison to the Fornax centre shows that the over-dense feature is consistent with the age-metallicity relation of young field stars, and likely formed from Fornax gas. This is consistent with a scenario in which the over-density was formed by the re-accretion of previously expelled gas. We have also discovered a new stellar over-density, located 0.3 degrees (0.7 kpc) from the centre, which is only 100 Myr old, with solar metallicity. This feature constitutes some of the youngest, most metal-rich stars stars observed in Fornax to date. It is unclear how the young over-density was formed, although the age and metallicity of stars suggest this feature may represent the last star formation activity of the Fornax dSph.
KW - Galaxies: evolution
KW - Galaxies: stellar content
KW - Hertzsprung-Russell and C-M diagrams
KW - Local Group
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U2 - 10.1051/0004-6361/201220855
DO - 10.1051/0004-6361/201220855
M3 - Article
AN - SCOPUS:84874629407
SN - 0004-6361
VL - 551
JO - Astronomy and astrophysics
JF - Astronomy and astrophysics
M1 - A103
ER -