J/ApJ/888/31ivo://CDS.VizieR/J/ApJ/888/31doi:10.26093/cds/vizier.18880031CDSHargis J.R.Albers S.Crnojevic D.Sand D.J.Weisz D.R.Carlin J.L.,Spekkens K.Willman B.Peter A.H.G.Grillmair C.J.Dolphin A.E.2021-10-25T10:03:38Z2021-07-07T13:44:30ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frgalaxiesvisible-astronomyhst-photometryA census of the satellite population around dwarf galaxy primary hosts in environments outside the Local Group is essential to understanding {Lambda} 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=1.3Mpc)-- 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+/-0.06Mpc (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 <~1Gyr. 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 ~10-11Gyr and almost no growth in the last ~2-3Gyr. Despite being gas-rich, Antlia B shows no evidence of active star formation (i.e., no H{alpha} emission) and should therefore be classified as a dTrans dwarf. Both Antlia B and the Antlia dwarf (dTrans) are likely satellites of NGC3109, 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.2020ApJ...888...31Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/888/31CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/hst : HST Archived Exposures Catalog (STScI, 2007)J/A+A/566/A44 : gr photometry of Sextans A and Sextans B (Bellazzini+, 2014)J/ApJ/843/16 : Galaxy groups within 3500km/s (Kourkchi+, 2017)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/ApJ/812/158 : Leo P RR Lyrae candidates & cumulative SFH (McQuinn+, 2015)J/AJ/156/18 : APOGEE DR14: companions of evolved stars (Price-Whelan+, 2018)J/AJ/116/2341 : UBVRI photometry in Sextans A (Van Dyk+ 1998)J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)J/ApJS/215/9 : PHAT X. UV-IR photometry of M31 stars (Williams+, 2014)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/888/31https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/888/31http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/888/31https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/888/31https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/888/31http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/888/31GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/888/31/table2 (Photometry of resolved stars in the HST/ACS imaging of Antlia B)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/888/31/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/888/31/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/888/31/table2?GETtext/xml+votable180.050000true147.2284601-26.02029660.0055555555555555566/402052.3657755224268815e-19 3.5452907792336973e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/888/31?format=asciiOpticaldefaultJ/ApJ/888/31/table2Photometry of resolved stars in the HST/ACS imaging of Antlia BrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[79/58692] Object identification numbermeta.id;meta.mainintRAJ2000[147.2/147.3] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-26.1/-25.9] Declination (J2000)degpos.eq.dec;meta.mainXpixHST/ACS X pixel coordinatepixpos.cartesian.xfloatYpixHST/ACS Y pixel coordinatepixpos.cartesian.yfloatOType[1] DOLPHOT object typesrc.classfloatF606Wmag[19/28] HST/ACS F606W band magnitude (1)magphot.mag;em.opt.Rfloate_F606Wmag[0.001/0.3] Uncertainty in F606Wmagmagstat.errorfloatSNR-F606W[5/801] Signal-to-Noise in F606W observationstat.snrfloatSh-F606W[-0.31/0.31] Sharp parameter value in F606W observationobs.param;obsfloatRd-F606W[-0.45/3] Round parameter value in F606W observationobs.param;obsfloatC-F606W[0/0.7] Crowding parameter in F606W observationobs.param;obsfloatq_F606Wmag[0/3] Quality flag in F606Wmag (2)meta.code.qualfloatF814Wmag[17.6/27.2] HST/ACS F814W band magnitude (1)magphot.mag;em.opt.Ifloate_F814Wmag[0.001/0.3] Uncertainty in F814Wmagmagstat.errorfloatSNR-F814W[5/946] Signal-to-Noise in F814W observationstat.snrfloatSh-F814W[-0.31/0.31] Sharp parameter value in F814W observationobs.param;obsfloatRd-F814W[-0.5/3.5] Round parameter value in F814W observationobs.param;obsfloatC-F814W[0/0.71] Crowding parameter in F814W observationobs.param;obsfloatq_F814Wmag[0/3] Quality flag in F814Wmag (2)meta.code.qualfloatE(B-V)[0.08/0.082] Schlegel+ 1998ApJ...500..525S (B-V) color excessmagphot.color.excessfloatAF606W[0.19/0.21] Milky Way extinction in F606W bandmagphys.absorptionfloatAF814W[0.122/0.125] Milky Way extinction in F814W bandmagphys.absorptionfloatJ/ApJ/888/31/table3Cumulative star formation history of Antlia BrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlog(t)[6.6/10.2] log epochlog(yr)time.epochfloatf[0/1] Fraction of total stellar mass formed prior to the corresponding epochtime.epoch;phys.massfloatsigRan84[0/0.07] Upper 84% random uncertainty in fstat.errorfloatsigRan16[0/0.08] Lower 16% random uncertainty in fstat.errorfloatsigTot84[0/0.4] Upper 84% total uncertainty in fstat.errorfloatsigTot16[0/0.3] Lower 16% total uncertainty in fstat.errorfloat