Antlia B: a faint dwarf galaxy member of the NGC 3109 association

Journal Article · Sat Oct 10 04:00:00 EDT 2015 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/812/1/L13· OSTI ID:22868724

Sand, D. J.; Crnojević, D. ^[1]; Spekkens, K. ^[2]; Hargis, J. R.; Willman, B. ^[3]; Strader, J. ^[4]

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1. Physics Department, Texas Tech University, Box 41051, Lubbock, TX 79409-1051 (United States)
2. Department of Physics, Royal Military College of Canada, P.O. Box 17000, Station Forces, Kingston, Ontario, K7K 7B4 (Canada)
3. Department of Astronomy, Haverford College, 370 Lancaster Avenue, Haverford, PA 19041 (United States)
4. Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

We report the discovery of Antlia B, a faint dwarf galaxy at a projected distance of ∼72 kpc from NGC 3109 (M{sub V} ∼ −15 mag), the primary galaxy of the NGC 3109 dwarf association at the edge of the Local Group. The tip of the red giant branch distance to Antlia B is D = 1.29 ± 0.10 Mpc, which is consistent with the distance to NGC 3109. A qualitative analysis indicates the new dwarf's stellar population has both an old, metal-poor red giant branch (≳10 Gyr, [Fe/H] ∼ −2), and a younger blue population with an age of ∼200–400 Myr, analogous to the original Antlia dwarf, another likely satellite of NGC 3109. Antlia B has H i gas at a velocity of v{sub helio,H I} = 376 km s{sup −1}, confirming the association with NGC 3109 (v{sub helio} = 403 km s{sup −1}). The H i gas mass (M{sub H i} = 2.8 ± 0.2 × 10{sup 5} M{sub ⊙}), stellar luminosity (M{sub V} = −9.7 ± 0.6 mag) and half light radius (r{sub h} = 273 ± 29 pc) are all consistent with the properties of dwarf irregular and dwarf spheroidal galaxies in the Local Volume, and is most similar to the Leo P dwarf galaxy. The discovery of Antlia B is the initial result from a Dark Energy Camera survey for halo substructure and faint dwarf companions to NGC 3109 with the goal of comparing observed substructure with expectations from the Λ+Cold Dark Matter model in the sub-Milky Way regime.

• OSTI ID: 22868724
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 812; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CAMERAS
GALAXY CLUSTERS
LUMINOSITY
MASS
METALS
MILKY WAY
NONLUMINOUS MATTER
RED GIANT STARS
SATELLITES