A NEW CHEMICAL EVOLUTION MODEL FOR DWARF SPHEROIDAL GALAXIES BASED ON OBSERVED LONG STAR FORMATION HISTORIES

Journal Article · Sun Feb 01 00:00:00 EST 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/799/2/230· OSTI ID:22364315

Homma, Hidetomo; Murayama, Takashi ^[1]; Kobayashi, Masakazu A. R.; Taniguchi, Yoshiaki ^[2]

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1. Astronomical Institute, Tohoku University, Aoba-ku, Sendai 980-8578 (Japan)
2. Research Center for Space and Cosmic Evolution, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan)

We present a new chemical evolution model for dwarf spheroidal galaxies (dSphs) in the local universe. Our main aim is to explain both their observed star formation histories and metallicity distribution functions simultaneously. Applying our new model for the four local dSphs, that is, Fornax, Sculptor, Leo II, and Sextans, we find that our new model reproduces the observed chemical properties of the dSphs consistently. Our results show that the dSphs have evolved with both a low star formation efficiency and a large gas outflow efficiency compared with the Milky Way, as suggested by previous works. Comparing the observed [α/Fe]-[Fe/H] relation of the dSphs with the model predictions, we find that our model favors a longer onset time of Type Ia supernovae (i.e., 0.5 Gyr) than that suggested in previous studies (i.e., 0.1 Gyr). We discuss the origin of this discrepancy in detail.

• OSTI ID: 22364315
• Journal Information: Astrophysical Journal, Vol. 799, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CHEMICAL PROPERTIES
COMPARATIVE EVALUATIONS
DISTRIBUTION FUNCTIONS
EFFICIENCY
METALLICITY
MILKY WAY
STAR EVOLUTION
STAR MODELS
SUPERNOVAE
UNIVERSE