The universal stellar mass-stellar metallicity relation for dwarf galaxies

Journal Article · Fri Dec 20 04:00:00 EST 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/779/2/102· OSTI ID:22348465

Kirby, Evan N.; Bullock, James S. ^[1]; Cohen, Judith G. ^[2]; Guhathakurta, Puragra ^[3]; Cheng, Lucy ^[4]; Gallazzi, Anna ^[5]

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1. University of California, Department of Physics and Astronomy, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States)
2. California Institute of Technology, Department of Astronomy and Astrophysics, 1200 E. California Blvd., MC 249-17, Pasadena, CA 91125 (United States)
3. UCO/Lick Observatory and Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
4. The Harker School, 500 Saratoga Ave., San Jose, CA 95117 (United States)
5. INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)

We present spectroscopic metallicities of individual stars in seven gas-rich dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same mass-metallicity relation as the dwarf spheroidal (dSph) satellites of both the Milky Way and M31: Z{sub ∗}∝M{sub ∗}{sup 0.30±0.02}. The uniformity of the relation is in contradiction to previous estimates of metallicity based on photometry. This relationship is roughly continuous with the stellar mass-stellar metallicity relation for galaxies as massive as M {sub *} = 10{sup 12} M {sub ☉}. Although the average metallicities of dwarf galaxies depend only on stellar mass, the shapes of their metallicity distributions depend on galaxy type. The metallicity distributions of dIrrs resemble simple, leaky box chemical evolution models, whereas dSphs require an additional parameter, such as gas accretion, to explain the shapes of their metallicity distributions. Furthermore, the metallicity distributions of the more luminous dSphs have sharp, metal-rich cut-offs that are consistent with the sudden truncation of star formation due to ram pressure stripping.

• OSTI ID: 22348465
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 779; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
DISTRIBUTION
DWARF STARS
GALAXIES
MASS
METALLICITY
METALS
MILKY WAY
PHOTOMETRY
SATELLITES
STARS
STRIPPING