J/AJ/170/76ivo://CDS.VizieR/J/AJ/170/76CDSHunter D.A.Zhang H.-X.Elmegreen B.G.Castelloe E.R.Ledford H.M.,Nisley I.Hatano R.2026-05-27T15:17:14Z2026-05-27T15:33:37ZCDS support team

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

cds-question@unistra.frdwarf-galaxiesgalaxiesinfrared-photometryvisible-astronomybroad-band-photometryh-i-line-emissionUltradeep UBVI imaging of 10 nearby (<=7.8Mpc) noninteracting dwarf irregular galaxies are used to examine their far outer stellar disks. The annulus between 26mag/arcsec^2^ and 29mag/arcsec^2^ in the V band is what we define as the far outer disk and is our focus here. Photometry of distinct objects in the far outer disks, including far-UV images, is used to determine ages of the objects in order to look for those that are young. In three of the galaxies we find objects with high-confidence ages <=30Myr. These objects are too young to have scattered into the far outer disk from the central regions. Therefore, they likely formed in situ. How star-forming gas clouds formed in the extreme environment of the outer stellar disks of dwarfs is a primary unanswered question.2025AJ....170...76Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/170/76CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/183A : UBVRI Photometric Standards (Landolt 1992)J/AJ/112/1335 : Hubble Deep Field observations (Williams+ 1996)J/AJ/123/3154 : RV light curves of variable stars in Leo A (Dolphin+, 2002)J/A+A/398/479 : Local galaxy flows within 5 Mpc (Karachentsev+, 2003)J/AJ/127/2031 : Catalog of neighboring galaxies (Karachentsev+, 2004)J/ApJS/162/49 : UBV imaging of irregular galaxies (Hunter+, 2006)J/AJ/144/134 : LITTLE THINGS survey of nearby dwarf galaxies (Hunter+, 2012)J/AJ/146/104 : Dwarf galaxies surface brightn. profiles. I. (Herrmann+, 2013)J/AJ/151/145 : Dwarf galaxies surface brightn. profiles. II. (Herrmann+, 2016)J/AJ/157/241 : HI clouds in LITTLE THINGS dwarf irreg. galaxies (Hunter+, 2019)J/A+A/667/A87 : Edges of galaxies. Limits of star formation (Chamba+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/170/76https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/170/76http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/170/76https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/170/76https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/170/76http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/170/76GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/170/76/table1 (Galaxy sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/170/76/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/170/76/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/170/76/table1?GETtext/xml+votable180.050000true112.07416740.7702780.005555555555555556Cone search capability for table J/AJ/170/76/table7 (Objects in far outer stellar disk)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/170/76/table7?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/170/76/table7?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/170/76/table7?GETtext/xml+votable180.050000true112.08916740.7678330.005555555555555556Cone search capability for table J/AJ/170/76/table12 (Objects in background)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/170/76/table12?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/170/76/table12?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/170/76/table12?GETtext/xml+votable180.050000true111.94666740.7398610.0055555555555555566/4522-4523 4746 4864-4865 5286-5287 5292-5293 5978 6398-6399 6560-6562 8908-8909 19833 19990 22495 48942-489433.322582951404819e-19 4.920466254354166e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/170/76?format=asciiOpticalInfraredRadiodefaultJ/AJ/170/76/table1Galaxy sampleSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameGalaxy namemeta.id;meta.maincharprimaryRAJ2000Hour of right ascension of the stellar disk center (J2000) (1)pos.eq.ra;meta.mainDEJ2000Degree of declination of the stellar disk center (J2000) (1)pos.eq.dec;meta.mainDist[0.7/8.7] Distance (2)Mpcpos.distancefloatVMag[-17.1/-9.7] Absolute V magnitude (1)magphys.magAbs;em.opt.VfloatRdisk[0.14/1.34] Stellar disk scale length (3)kpcsrc.morph.scLengthfloate_Rdisk[0.01/0.1] Rdisk uncertainty (3)kpcstat.errorfloatPA[-85/84] Position angle (1)degpos.posAngfloatb/a[0.45/1] Minor-to-major disk axes ratio (1)phys.angSize;arith.ratiofloatE(B-V)f[0/0.05] Foreground reddening from the Milky Way (4)magphot.color.excessfloatlog(MHI)[5.19/8.59] Log of HI mass (1)log(solMass)phys.massfloatnOutNumber of objects in the far outer stellar disk (link to Table 7)meta.numberintnullablenBkgNumber of objects in the background (link to Table 12)meta.numberintnullableImV-band image (Figure 2)meta.ref.urlcharDiagOptical CMDs and CCDs for far outer disk objects (Figure 19)meta.ref.urlcharJ/AJ/170/76/table7Objects in far outer stellar diskNameGalaxy namemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[1/6131] Running ID numbermeta.idintRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainindexedDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainRphot[0.3/18.4] Radius of aperture used for photometryarcsecphys.angSize;srcfloatBmag[18.32/99.99]? Apparent Johnson B magnitude (1)magphot.mag;em.opt.Bfloatnullablee_Bmag[0.0/9.99]? Uncertainty in Bmagmagstat.error;phot.mag;em.opt.BfloatnullableVmag[16.45/99.99]? Apparent Johnson V magnitude (1)magphot.mag;em.opt.Vfloatnullablee_Vmag[0.0/9.99]? Uncertainty in Vmagmagstat.error;phot.mag;em.opt.VfloatnullableU-B[-2.86/99.99]? U-B color (1)magphot.color;em.opt.U;em.opt.Bfloatnullablee_U-B[0.0/9.99]? Uncertainty in U-Bmagstat.error;phot.color;em.opt.UfloatnullableB-V[-3.92/99.99]? B-V color (1)magphot.color;em.opt.B;em.opt.Vfloatnullablee_B-V[0.0/9.99]? Uncertainty in B-Vmagstat.error;phot.color;em.opt.BfloatnullableV-I[-3.93/99.99]? V-I color (1)magphot.color;em.opt.V;em.opt.Ifloatnullablee_V-I[0.0/9.99]? Uncertainty in V-Imagstat.error;phot.color;em.opt.VfloatnullableJ/AJ/170/76/table12Objects in backgroundNameGalaxy namemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[1/13640] Running ID numbermeta.idintRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainindexedDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainRphot[0.1/17.9] Radius of aperture used for photometryarcsecphys.angSize;srcfloatBmag[17.5/99.99]? Apparent Johnson B magnitude (1)magphot.mag;em.opt.Bfloatnullablee_Bmag[0.0/9.99]? Uncertainty in Bmagmagstat.error;phot.mag;em.opt.BfloatnullableVmag[16.47/99.99]? Apparent Johnson V magnitude (1)magphot.mag;em.opt.Vfloatnullablee_Vmag[0.0/9.99]? Uncertainty in Vmagmagstat.error;phot.mag;em.opt.VfloatnullableU-B[-3.21/99.99]? U-B color (1)magphot.color;em.opt.U;em.opt.Bfloatnullablee_U-B[0.0/9.99]? Uncertainty in U-Bmagstat.error;phot.color;em.opt.UfloatnullableB-V[-4.74/99.99]? B-V color (1)magphot.color;em.opt.B;em.opt.Vfloatnullablee_B-V[0.0/9.99]? Uncertainty in B-Vmagstat.error;phot.color;em.opt.BfloatnullableV-I[-8.51/99.99]? V-I color (1)magphot.color;em.opt.V;em.opt.Ifloatnullablee_V-I[0.0/9.99]? Uncertainty in V-Imagstat.error;phot.color;em.opt.Vfloatnullable