TY - JOUR
T1 - Star formation in ultra-faint dwarfs
T2 - Continuous or single-age bursts?
AU - Webster, David
AU - Bland-Hawthorn, Joss
AU - Sutherland, Ralph
N1 - Publisher Copyright:
© 2015. The American Astronomical Society. All rights reserved.
PY - 2015/2/1
Y1 - 2015/2/1
N2 - We model the chemical evolution of six ultra-faint dwarfs (UFDs): Bootes I, Canes Venatici II, Coma Berenices, Hercules, Leo IV, and Ursa Major I based on their recently determined star formation histories. We show that two single-age bursts cannot explain the observed [α/Fe] versus [Fe/H] distribution in these galaxies and that some self-enrichment is required within the first burst. An alternative scenario is modeled, in which star formation is continuous except for short interruptions when one or more supernovae temporarily blow the dense gas out from the center of the system. This model allows for self-enrichment and can reproduce the chemical abundances of the UFDs in which the second burst is only a trace population. We conclude that the most likely star formation history is one or two extended periods of star formation, with the first burst lasting for at least 100 Myr. As found in earlier work, the observed properties of UFDs can be explained by formation at a low mass (Mvir ∼ 107 M⊙), rather than being stripped remnants of much larger systems.
AB - We model the chemical evolution of six ultra-faint dwarfs (UFDs): Bootes I, Canes Venatici II, Coma Berenices, Hercules, Leo IV, and Ursa Major I based on their recently determined star formation histories. We show that two single-age bursts cannot explain the observed [α/Fe] versus [Fe/H] distribution in these galaxies and that some self-enrichment is required within the first burst. An alternative scenario is modeled, in which star formation is continuous except for short interruptions when one or more supernovae temporarily blow the dense gas out from the center of the system. This model allows for self-enrichment and can reproduce the chemical abundances of the UFDs in which the second burst is only a trace population. We conclude that the most likely star formation history is one or two extended periods of star formation, with the first burst lasting for at least 100 Myr. As found in earlier work, the observed properties of UFDs can be explained by formation at a low mass (Mvir ∼ 107 M⊙), rather than being stripped remnants of much larger systems.
KW - Dark ages
KW - First stars
KW - Galaxies: abundances
KW - Galaxies: dwarf
KW - Galaxies: formation
KW - Galaxies: star formation
KW - Reionization
UR - http://www.scopus.com/inward/record.url?scp=84922362556&partnerID=8YFLogxK
U2 - 10.1088/2041-8205/799/2/L21
DO - 10.1088/2041-8205/799/2/L21
M3 - Article
SN - 2041-8205
VL - 799
SP - 1
EP - 6
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L21
ER -