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Published October 10, 2015 | Published + Submitted
Journal Article Open

Antlia B: A Faint Dwarf Galaxy Member of the NGC 3109 Association


We report the discovery of Antlia B, a faint dwarf galaxy at a projected distance of ~72 kpc from NGC 3109 (M_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_(helio,HI) = 376 km s^(−1), confirming the association with NGC 3109 (v_(helio) = 403 km s^(−1)). The H i gas mass (M_(H i) = 2.8 ± 0.2 × 10^5 M_☉), stellar luminosity (M_V = −9.7 ± 0.6 mag) and half light radius (r_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.

Additional Information

© 2015. The American Astronomical Society. Received 2015 August 6; accepted 2015 September 14; published 2015 October 9. D.J.S. acknowledges support from NSF grant AST-1412504. K.S. acknowledges support from the Natural Sciences and Engineering Research Council of Canada. B.W. and J.H. were supported by an NSF Faculty Early Career Development (CAREER) award (AST-1151462). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This work was supported in part by National Science Foundation grant No. PHYS-1066293 and the Aspen Center for Physics. This project used data obtained with the Dark Energy Camera, which was constructed by the Dark Energy Survey collaboration. Funding for the DES Projects has been provided by the DOE and NSF(USA), MISE(Spain), STFC(UK), HEFCE(UK). NCSA(UIUC), KICP(U. Chicago), CCAPP(Ohio State), MIFPA(Texas A&M), CNPQ, FAPERJ, FINEP (Brazil), MINECO(Spain), DFG(Germany) and the collaborating institutions in the DES, which are Argonne Lab, UC Santa Cruz, University of Cambridge, CIEMAT-Madrid, University of Chicago, University College London, DES-Brazil Consortium, University of Edinburgh, ETH Zurich, Fermilab, University of Illinois, ICE (IEEC-CSIC), IFAE Barcelona, Lawrence Berkeley Lab, LMU Munchen and the associated Excellence Cluster Universe, University of Michigan, NOAO, University of Nottingham, Ohio State University, University of Pennsylvania, University of Portsmouth, SLAC National Lab, Stanford University, University of Sussex, and Texas A&M University.

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Submitted - 1508.01800v1.pdf

Published - Sand_2015pL13.pdf


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August 22, 2023
August 22, 2023