J/ApJ/827/89ivo://CDS.VizieR/J/ApJ/827/89doi:10.26093/cds/vizier.18270089CDSTollerud E.J.Geha M.C.Grcevich J.Putman M.E.Weisz D.R.,Dolphin A.E.2017-10-11T05:13:03Z2017-01-03T14:16:59ZCDS support team

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

cds-question@unistra.frgalaxieshst-photometryradial-velocityWe present observations of the Pisces A and B galaxies with the Advanced Camera for Surveys on the Hubble Space Telescope. Photometry from these images clearly resolves a red giant branch (RGB) for both objects, demonstrating that they are nearby dwarf galaxies. We describe a Bayesian inferential approach to determining the distance to these galaxies using the magnitude of the tip of the RGB (TRGB), and then apply this approach to these galaxies. This reveals the distance to these galaxies as 5.64_-0.15_^+0.13^Mpc and 8.89_-0.85_^+0.75^Mpc for Pisces A and B, respectively, placing both within the Local Volume but not the Local Group (LG). We estimate the star formation histories of these galaxies, which suggests that they have recently undergone an increase in their star formation rates. Together these yield luminosities for Pisces A and B of M_V_=-11.57_-0.05_^+0.06^ and -12.9+/-0.2, respectively, and estimated stellar masses of log(M*/M_{sun})=7.0_-1.7_^+0.4^ and 7.5_-1.8_^+0.3^. We further show that these galaxies are likely at the boundary between nearby voids and higher-density filamentary structure. This suggests that they are entering a higher-density region from voids, where they would have experienced delayed evolution, consistent with their recent increased star formation rates. If this is indeed the case, they are useful for study as proxies of the galaxies that later evolved into typical LG satellite galaxies.2016ApJ...827...89Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/827/89CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)J/A+A/587/L3 : HI datacubes if Pisces A and B (Carignan+, 2016)J/ApJ/806/95 : A search for ultra-compact HVC counterparts (Sand+, 2015)J/AJ/144/16 : Optical and HI properties of galaxies in voids (Kreckel+, 2012)J/AJ/144/4 : Dwarf galaxies data in the Local Group (McConnachie+, 2012)J/ApJ/653/240 : Low-mass SDSS dwarf galaxy properties (Geha+, 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/827/89https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/827/89http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/827/89https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/827/89https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/827/89http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/827/89GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/827/89/table1 (Key properties of pisces A and B)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/827/89/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/827/89/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/827/89/table1?GETtext/xml+votable180.050000true3.69166710.8130580.0055555555555555566/18335 195652.0401237512456292e-19 3.9057996558789745e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/827/89?format=asciiOpticaldefaultJ/ApJ/827/89/table1Key properties of pisces A and BE_F814W0Positive uncertainty on F814W0magstat.error;stat.maxfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameObject namemeta.id;meta.maincharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainGLATGalactic latitudedegpos.galactic.latfloatGLONGalactic longitudedegpos.galactic.lonDistDistance (section 3)Mpcpos.distance;pos.heliocentricfloate_DistNegative uncertainty on DistMpcstat.errorfloatE_DistPositive uncertainty on DistMpcstat.error;stat.maxfloatf_Dist[a] Flag on Dist (1)meta.codecharM-mDistance modulus from Tip of the RGB (TRGB)magphot.mag.distModfloate_M-mNegative uncertainty on M-mmagstat.errorfloatE_M-mPositive uncertainty on M-mmagstat.error;stat.maxfloatf_M-m[a] Flag on M-m (1)meta.codecharF814WF814W magnitude of the TRGB ({mu}_F814W_)magphot.mag;em.opt.Ifloate_F814WNegative uncertainty on F814Wmagstat.errorfloatE_F814WPositive uncertainty on F814Wmagstat.error;stat.maxfloatf_F814W[a] Flag on F814W (1)meta.codecharF606W0Absolute F606W magnitude (section 4)magphot.mag;em.opt.Rfloate_F606W0Negative uncertainty on F606W0magstat.errorfloatE_F606W0Positive uncertainty on F606W0magstat.error;stat.maxfloatf_F606W0[a] Flag on F606W0 (1)meta.codecharF814W0Absolute F814W magnitude (section 4)magphot.mag;em.opt.Ifloate_F814W0Negative uncertainty on F814W0magstat.errorfloatf_F814W0[a] Flag on F814W0 (1)meta.codecharVMagAbsolute V-band magnitude (2)magphot.mag;em.opt.Vfloate_VMagNegative uncertainty on VMagmagstat.error;phot.mag;em.opt.VfloatE_VMagPositive uncertainty on VMagmagstat.error;stat.maxfloatf_VMag[a] Flag on VMag (1)meta.codecharV-IV-I color index (2)magphot.color;em.opt.V;em.opt.Ifloate_V-IV-I uncertaintymagstat.error;phot.color;em.opt.VfloatReffOn-sky major axis half-light radius from F606W imaging (section 4) in arcsecarcsecphys.angSizefloate_ReffReff uncertaintyarcsecstat.errorfloatreffPhysical half-light radius in F606W in pcpcphys.size.radiusinte_reffNegative uncertainty on reffpcstat.errorintE_reffPositive uncertainty on reffpcstat.error;stat.maxintf_reff[a] Flag on reff (1)meta.codecharnSersic Index from F606W imaging (section 4)stat.fit.paramfloate_nNegative uncertainty on nstat.errorfloatE_nPositive uncertainty on nstat.error;stat.maxfloatellEllipticity in F606W (1-b/a)src.ellipticityfloate_ellell uncertaintystat.errorfloatPAPosition angle of major axis in F606W {theta} (East of North)degpos.posAnginte_PAPA uncertaintydegstat.errorfloatlogM*Total stellar mass as inferred from the CMD (3)log(solMass)phys.massfloate_logM*Negative uncertainty on logM*log(solMass)stat.errorfloatE_logM*Positive uncertainty on logM*log(solMass)stat.error;stat.maxfloatMHIHI gas mass from GALFA-HI (4)1e+06solMassphys.massfloate_MHINegative uncertainty on MHI1e+06solMassstat.errorfloatE_MHIPositive uncertainty on MHI1e+06solMassstat.error;stat.maxfloatf_MHI[a] Flag on MHI (1)meta.codecharVelISystemic heliocentric velocity of HI gaskm/sspect.dopplerVeloc;em.line.HIinte_VelIVelI uncertaintykm/sstat.errorfloatW50HIW50 of HI gaskm/sspect.line.widthfloate_W50HIW50HI uncertaintykm/sstat.errorfloatVelOptival heliocentric velocity (5)km/sspect.dopplerVeloc;pos.heliocentricinte_VelVel uncertaintykm/sstat.errorintSimbadSimbad column added by the CDSmeta.ref.urlcharJ/ApJ/827/89/table2Distributions of quantitiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDistA[4.8/7.5] Distance, Pisces AMpcpos.distance;pos.heliocentricfloatmu814A[24/25.3] F814W magnitude of the TRGB, Pisces Amagphot.mag;em.opt.IfloatColTRGBA[0.7/0.9] (F606W-F814W)0 color of the TRGB, Pisces Amagphot.color;em.opt.V;em.opt.IfloatalphaA[0.0008/0.9] TRGB model, power law slope for the RGB component, Pisces A (1)stat.paramfloatbetaA[0.3/2] TRGB model, power-law slope for the non-RGB population, Pisces A (1)stat.paramfloatfATRGB model, fraction of stars in the non-RGB relative to those in the RGB, Pisces A (1)stat.paramfloatF606WA[17.3/17.4] HST ACS/WFC F606W, Pisces Amagphot.mag;em.opt.RfloatF814WA[16.5/16.7] HST ACS/WFC F814W, Pisces Amagphot.mag;em.opt.IfloatnA[0.42/0.54] Sersic Index, Pisces Astat.fit.paramfloatellA[0.29/0.4] Ellipticity in F606W, Pisces Asrc.ellipticityfloatPAA[131/142] Position angle, Pisces Adegpos.posAngdoubleReffA[8.7/9.5] on-sky half-light radius in F606W, Pisces Aarcsecphys.angSize;srcfloatreffA[118/194] Physical half-light radius in F606W, Pisces Apcphys.size.radiusdoubleDistB[6.7/12.3] Distance, Pisces BMpcpos.distance;pos.heliocentricfloatmu814B[25/26.4] F814W magnitude of the TRGB, Pisces Bmagphot.mag;em.opt.IfloatColTRGBB[0.8/0.91] (F606W-F814W)0 color of the TRGB, Pisces Bmagphot.color;em.opt.V;em.opt.IfloatalphaB[0/1.3] TRGB model, power law slope for the RGB component, Pisces B (1)stat.paramfloatbetaB[1/5] TRGB model, power-law slope for the non-RGB population, Pisces B (1)stat.paramfloatfBTRGB model, fraction of stars in the non-RGB relative to those in the RGB, Pisces B (1)stat.paramfloatF606WB[16.9/17] HST ACS/WFC F606W, Pisces Bmagphot.mag;em.opt.RfloatF814WB[16.4/16.5] HST ACS/WFC F814W, Pisces Bmagphot.mag;em.opt.IfloatnB[0.63/0.66] Sersic Index, Pisces Bstat.fit.paramfloatellB[0.51/0.53] Ellipticity in F606W, Pisces Bsrc.ellipticityfloatPAB[138/140] Position angle, Pisces Bdegpos.posAngdoubleReffB[10.2/10.6] on-sky half-light radius in F606W, Pisces Barcsecphys.angSize;srcfloatreffB[242/446] Physical half-light radius in F606, Pisces Bpcphys.size.radiusdouble