J/ApJ/806/95ivo://CDS.VizieR/J/ApJ/806/95doi:10.26093/cds/vizier.18060095CDSSand D.J.Crnojevic D.Bennet P.Willman B.Hargis J.Strader J.,Olszewski E.Tollerud E.J.Simon J.D.Caldwell N.Guhathakurta P.,James B.L.Koposov S.McLeod B.Morrell N.Peacock M.Salinas R.,Seth A.C.Stark D.P.Toloba E.2017-09-29T09:03:15Z2015-11-16T09:39:42ZCDS support team

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

cds-question@unistra.frh-i-line-emissiongalaxiesvisible-astronomyultraviolet-astronomyWe report five Local Volume dwarf galaxies (two of which are presented here for the first time) uncovered during a comprehensive archival search for optical counterparts to ultra-compact high-velocity clouds (UCHVCs). The UCHVC population of HI clouds are thought to be candidate gas-rich, low-mass halos at the edge of the Local Group and beyond, but no comprehensive search for stellar counterparts to these systems has been presented. Careful visual inspection of all publicly available optical and ultraviolet imaging at the position of the UCHVCs revealed six blue, diffuse counterparts with a morphology consistent with a faint dwarf galaxy beyond the Local Group. Optical spectroscopy of all six candidate dwarf counterparts show that five have an H{alpha}-derived velocity consistent with the coincident HI cloud, confirming their association; the sixth diffuse counterpart is likely a background object. The size and luminosity of the UCHVC dwarfs is consistent with other known Local Volume dwarf irregular galaxies. The gas fraction (M_HI_/M_star_) of the five dwarfs are generally consistent with that of dwarf irregular galaxies in the Local Volume, although ALFALFA-Dw1 (associated with ALFALFA UCHVC HVC274.68+74.70-123) has a very high M_HI_/M_star_~40. Despite the heterogeneous nature of our search, we demonstrate that the current dwarf companions to UCHVCs are at the edge of detectability due to their low surface brightness, and that deeper searches are likely to find more stellar systems. If more sensitive searches do not reveal further stellar counterparts to UCHVCs, then the dearth of such systems around the Local Group may be in conflict with {Lambda}CDM simulations.2015ApJ...806...95Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/806/95CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/cfht : Log of CFHT Exposures (CADC, 1979-)J/AJ/146/145 : ALFALFA discovery of Leo P. IV. VI photometry (Mcquinn+, 2013)J/AJ/145/149 : ALFALFA discovery of Leo P. II. BVR photometry (Rhode+, 2013)J/ApJ/768/77 : Ultra-compact high velocity clouds from ALFALFA (Adams+, 2013)J/AJ/145/101 : Updated nearby galaxy catalog (Karachentsev+, 2013)J/ApJ/758/44 : The GALFA-HI compact cloud catalog (Saul+, 2012)J/ApJ/756/79 : Opt. photometry in 3 Local Group dwarf galaxies (Sand+, 2012)J/AJ/144/4 : Dwarf galaxies data in the Local Group (McConnachie+, 2012)J/AJ/142/170 : ALFALFA survey: the {alpha}.40 HI sources (Haynes+, 2011)J/AJ/139/315 : HI-selected galaxies in SDSS. Optical data (West+, 2010)J/AJ/133/2569 : Arecibo legacy fast ALFA survey III. (Giovanelli+, 2007)J/ApJ/655/144 : ACS Virgo Cluster Survey. XIII. (Mei+, 2007)J/AJ/130/873 : Properties of BQS objects in the SDSS DR3 area (Jester+, 2005)J/MNRAS/361/34 : HIPASS catalogue. III. (Doyle+, 2005)J/ApJ/623/181 : Compact high-velocity cloud photometry catalog (Siegel+, 2005)J/AJ/129/1311 : J-band photometry of ADBS Galaxies (Rosenberg+, 2005)J/AJ/123/873 : HIPASS high-velocity clouds (Putman+, 2002)J/ApJS/119/159 : Deep survey of HI-selected galaxies (Spitzak+, 1998)http://www.sdss3.org/ : SDSS-III home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/806/95https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/806/95http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/806/95https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/806/95https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/806/95http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/806/95GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/806/95/table1 (Summary of ultra-compact high-velocity cloud (UCHVC) archival search)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/806/95/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/806/95/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/806/95/table1?GETtext/xml+votable180.050000true3.687510.8166670.0055555555555555566/207 824 1207 2126 2149 2211 2216 4384 4585 4828 4842 4843 6695 8244 8302 8303 8328 8388 8473 8512 8514 8932 12659 12758 13350 13354 13422 13466 13473 13486 18335 18414 19269 19275 19304 19565 19784 20014 20146 20334 20373 22227 22271 22487 23657 23710 24191 24427 24478 26073 26076 26102 26352 26363 26383 26499 26505 26523 26570 26600 27101 27111 27124 27382 27454 27515 27667 27673 27714 27719 27729 27733 27775 27808 27942 28224 31526 31691 31715 31720https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/806/95?format=asciiRadioOpticalUVdefaultJ/ApJ/806/95/table1Summary of ultra-compact high-velocity cloud (UCHVC) archival searchrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSurveySurvey (ALFALFA or GALFA-HI)meta.notecharIDUltra-compact high-velocity clouds (UCHVC) ID (see the "Nomenclature" section below)meta.id;meta.maincharprimarydGDisplay the spectroscopy logmeta.ref.urlcharRAJ2000[0/23] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[4/36] Degree of Declination (J2000)pos.eq.dec;meta.mainVLSR[-454/615] HI Local Standard of Rest velocitykm/sstat.errorfloatOptOptical Datameta.code;instr.filtercharn_OptNotes on Opt (1)meta.notecharGALEXGALEX Datainstr.bandpasscharn_GALEXNotes on GALEX (2)meta.notecharCommComments (3)meta.notecharSloanDisplay the online SDSS data for the nearest sourcemeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/ApJ/806/95/table3Spectroscopy log of dwarf galaxy candidatesTargetTarget designationmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSurvey("HVC" for ALFALFA or "GALFA" for GALFA-HI)meta.idcharIDUCHVC IDmeta.id;meta.maincharTelTelescope/Instrumentmeta.notecharDateObservation datetime.epoch;obsnullableExp1Exposure time 1time.duration;obs.exposureintExp2Exposure time 2time.duration;obs.exposureintVlsr[-114/5730] H{alpha} LSR velocitykm/sphys.veloc;pos.lsrinte_Vlsr[8/200] Vlsr uncertaintykm/sstat.error;phys.veloc;pos.lsrintNotesNotesmeta.notecharSimbadSimbad column added by the CDSmeta.ref.urlchar