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Hubble Space Telescope Imaging of Antlia B: Star Formation History and a New Tip of the Red Giant Branch Distance

Hargis, J. R. and Albers, S. and Crnojević, D. and Sand, D. J. and Weisz, D. R. and Carlin, J. L. and Spekkens, K. and Willman, B. and Peter, A. H. G. and Grillmair, C. J. and Dolphin, A. E. (2020) Hubble Space Telescope Imaging of Antlia B: Star Formation History and a New Tip of the Red Giant Branch Distance. Astrophysical Journal, 888 (1). Art. No. 31. ISSN 1538-4357.

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A census of the satellite population around dwarf galaxy primary hosts in environments outside the Local Group is essential to understanding Λ cold dark matter galaxy formation and evolution on the smallest scales. We present deep optical Hubble Space Telescope imaging of the gas-rich, faint dwarf galaxy Antlia B (M_V = −9.4)—a likely satellite of NGC 3109 (D = 1.3 Mpc)—discovered as part of our ongoing survey of primary host galaxies similar to the Magellanic Clouds. We derive a new tip of the red giant branch distance of D = 1.35 ± 0.06 Mpc (m − M = 25.65 ± 0.10), consistent with membership in the nearby NGC 3109 dwarf association. The color–magnitude diagram (CMD) shows both a prominent old, metal-poor stellar component and confirms a small population of young, blue stars with ages ≾1 Gyr. We use the CMD fitting algorithm MATCH to derive the star formation history (SFH) and find that it is consistent with the typical dwarf irregular or transitional dwarf galaxy (dTrans) in the Local Group. Antlia B shows relatively constant stellar mass growth for the first ~10–11 Gyr and almost no growth in the last ~2–3 Gyr. Despite being gas-rich, Antlia B shows no evidence of active star formation (i.e., no Hα emission) and should therefore be classified as a dTrans dwarf. Both Antlia B and the Antlia dwarf (dTrans) are likely satellites of NGC 3109, suggesting that the cessation of ongoing star formation in these galaxies may be environmentally driven. Future work studying the gas kinematics and distribution in Antlia B will explore this scenario in greater detail. Our work highlights the fact that detailed studies of nearby dwarf galaxies in a variety of environments may continue to shed light on the processes that drive the SFH and evolution of dwarf galaxies more generally.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hargis, J. R.0000-0002-8722-9806
Albers, S.0000-0001-5496-2668
Crnojević, D.0000-0002-1763-4128
Sand, D. J.0000-0003-4102-380X
Weisz, D. R.0000-0002-6442-6030
Carlin, J. L.0000-0002-3936-9628
Spekkens, K.0000-0002-0956-7949
Willman, B.0000-0003-2892-9906
Peter, A. H. G.0000-0002-8040-6785
Grillmair, C. J.0000-0003-4072-169X
Dolphin, A. E.0000-0001-8416-4093
Additional Information:© 2020 The American Astronomical Society. Received 2019 August 2; revised 2019 October 25; accepted 2019 November 5; published 2020 January 3. We would like to thank the referee for the excellent feedback that significantly improved this paper. J.R.H. acknowledges support from HST award GO-14078 and the hospitality of the Texas Tech University Department of Physics and Astronomy and the University of Arizona Department of Astronomy/Steward Observatory. S.M.A. is supported by the National Science Foundation Graduate Research Fellowship under Grant DGE 1752814. Research by D.J.S. is supported by NSF grants AST-1821967, 1821987, 1813708, and 1813466. Research by D.C. is supported by NSF grant AST-1814208, and by NASA through grants No. HST-GO-15426.007-A and HST-GO-HST-GO-15332.004-A from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. K.S. acknowledges support from the Natural Sciences and Engineering Research Council of Canada. B.W. and J.C. were supported by an NSF Faculty Early Career Development (CAREER) award (AST-1151462). D.R.W. acknowledges fellowships from the Alfred P. Sloan Foundation and the Alexander von Humboldt Foundation. A.H.G.P. is supported by NSF grant AST-1813628. This work was partially performed at the Aspen Center for Physics, which is supported by National Science Foundation grant PHY-1607611. Facility: HST. - Software: astropy (Astropy Collaboration et al. 2013, 2018), MATCH (Dolphin 2002).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASA Hubble FellowshipGO-14078
NSF Graduate Research FellowshipDGE-1752814
NASA Hubble FellowshipHST-GO-15426.007-A
NASA Hubble FellowshipHST-GO-15332.004-A
NASANAS 5-26555
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
Subject Keywords:Dwarf galaxies; Dwarf irregular galaxies; Star formation; Hubble Space Telescope
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Dwarf galaxies (416); Dwarf irregular galaxies (417); Star formation (1569); Hubble Space Telescope (761)
Record Number:CaltechAUTHORS:20190730-072857235
Persistent URL:
Official Citation:J. R. Hargis et al 2020 ApJ 888 31
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97500
Deposited By: Tony Diaz
Deposited On:30 Jul 2019 15:36
Last Modified:08 Jan 2020 23:00

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