The Dwarf Galaxy Leo A: A Survivor From the Epoch of Reionization

Bibcode
2006AAS...20917806C
Cole, Andrew A.; Skillman, E. D.; Dolphin, A. E.; Gallagher, J. S., III; Tolstoy, E.; Gallart, C.; Weisz, D.; Hidalgo, S. L.; Saha, A.; Stetson, P. B.; Aparicio, A.
Bibliographical reference

2007 AAS/AAPT Joint Meeting, American Astronomical Society Meeting 209, #178.06; Bulletin of the American Astronomical Society, Vol. 38, p.1156

Advertised on:
12
2006
Number of authors
11
IAC number of authors
0
Citations
0
Refereed citations
0
Description
We present the results of a program to derive the complete star-formation history of the Local Group dwarf irregular galaxy Leo A (DDO 69). Leo A is a low-luminosity (Mv = -11.7), very gas-rich (M(HI)/LB = 1.6) galaxy. Our analysis is based on color-magnitude diagrams derived from deep HST/ACS imaging; the CMDs reach well below the oldest main-sequence turnoff of Leo A, at I ≈ 28. Over 80% of all the stars ever created in Leo A were born more recently than 7.7 Gyr ago (redshift z = 1 in a flat ΛCDM universe). The star-formation rate from 8-12 Gyr ago is formally consistent with zero, but stars as old as the oldest globular clusters are present. These results are discussed in the context of the predicted effects of cosmological reionization on the evolution of dwarf galaxies.
Type
Non-refereed

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