J/ApJ/899/14ivo://CDS.VizieR/J/ApJ/899/14doi:10.26093/cds/vizier.18990014CDSLong K.S.Blair W.P.Winkler P.F.Lacey C.K.2022-06-13T13:27:50Z2021-10-27T07:32:37ZCDS support team

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

cds-question@unistra.frsupernova-remnantsinterstellar-mediumhst-photometryvisible-astronomyinfrared-astronomyNGC6946 is a high-star-formation-rate, face-on, spiral galaxy that has hosted 10 supernovae since 1917. Not surprisingly, a large number of supernova remnants and candidates have been identified either as optical nebulae with high [SII]:H{alpha} line ratios (147) or as compact non-thermal radio sources (35). However, there are only seven overlaps between these two samples. Here, we apply [FeII] 1.644{mu}m emission as a new diagnostic to search for supernova remnants in an attempt to resolve this discrepancy. [FeII] is expected to be relatively strong in the radiative shocks of supernova remnants and almost absent in HII regions. It is less susceptible to the effects of absorption along the line of sight than the optical lines normally used to identify remnants. Using data from the WFC3 camera on Hubble Space Telescope (HST), we identify 132 [FeII] emission nebulae in NGC6946 as likely supernova remnants. Of these, 54 align with previously known optical supernova remnants. The remaining 78 objects are new; of these 44 are visible in new HST imagery in H{alpha} and [SII]. This brings the total number of supernova remnant candidates (from optical and/or IR data) in NGC6946 to 225. A total of 14 coincidences with radio supernova remnant candidates (out of 30 in our search area) are found in this expanded list. The identification of so many new remnant candidates validates the use of [FeII] imagery for finding remnants, and suggests that previous remnant searches in other galaxies may be far from complete.2020ApJ...899...14Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/899/14CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)J/ApJS/177/465 : X-ray variability in NGC 6946, NGC 4485/90 (Fridriksson+,2008)J/ApJ/788/55 : HST/WFC3 SNR discoveries in M83 (NGC5236) (Blair+, 2014)J/ApJ/855/140 : MMT spectra of SNRs and SNR candidates in M33 (Long+, 2018)J/ApJ/875/85 : Optical search SNRs in NGC6946 with WIYN & GMOS (Long+, 2019)J/ApJ/875/136 : BVRI, spectra & IR obs. of type II-P SN2017eaw (Van Dyk+,2019)J/ApJ/881/54 : Masses of SNR progenitors in M83 (Williams+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/899/14https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/899/14http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/899/14https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/899/14https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/899/14http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/899/14GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/899/14/table1 ([FeII] sources)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/899/14/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/899/14/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/899/14/table1?GETtext/xml+votable180.050000true308.597416760.13844440.005555555555555556Cone search capability for table J/ApJ/899/14/table2 (Optical SNRs)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/899/14/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/899/14/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/899/14/table2?GETtext/xml+votable180.050000true308.562560.17897220.0055555555555555566/15592-15593https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/899/14?format=asciiOpticalInfrareddefaultJ/ApJ/899/14/table1[FeII] sourcesSimbadNameSimbad column added by the CDSmeta.idcharnullableDist[6/49] Distancepcpos.distanceintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameIdentifiermeta.id;meta.maincharRAJ2000[20] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[60] Degree of Declination (J2000)pos.eq.dec;meta.mainR[0.1/8.2] Galactic distancekpcpos.distancefloatFFe[3.1/415] [FeII] flux; 1e-17erg/s/cm^2^1e-17mW.m**-2phot.flux.density;em.IRfloate_FFe[0.2/49] Uncertainty in FFe1e-17mW.m**-2stat.errorfloatFPaB[-19/352]? Pa{Beta} flux; 1e-17erg/s/cm^2^ (1)1e-17mW.m**-2phot.flux.density;em.IRfloatnullableEnvEnvironment code (2)meta.codechare_FPaB[0.2/32.7]? Uncertainty in FPaB1e-17mW.m**-2stat.errorfloatnullableOptOptical detection identifier (3)meta.idcharRadRadio detection identifier (5)meta.id.crosscharBruBruursema+, 2014AJ....148...41B survey identifier <L19 => [LWB2019] NNN> (3)meta.id.crosscharX-rayX-ray detection identifier (4)meta.id.crosscharJ/ApJ/899/14/table2Optical SNRsSimbadNameSimbad column added by the CDSmeta.idcharnullableNameIdentifiermeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000[20] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[60] Degree of Declination (J2000)pos.eq.dec;meta.mainDist[12/337] Distancepcpos.distanceintR[0.2/13.3] Galactic distancekpcpos.distancefloatConfConfirmed (1)meta.codecharFeIIcatThe [FeII] catalog (2)meta.id;meta.tablecharFFe[-5.3/415]? [FeII] flux; 1e-17erg/s/cm^2^ (3)1e-17mW.m**-2phot.flux.density;em.optfloatnullablee_FFe[0.4/49]? Uncertainty in FFe1e-17mW.m**-2stat.errorfloatnullableFPaB[-11.1/59.1]? Pa{beta} flux; 1e-17erg/s/cm^2^ (3)1e-17mW.m**-2phot.flux.density;em.optfloatnullablee_FPaB[0.3/14.0]? Uncertainty in FPaB1e-17mW.m**-2stat.errorfloatnullable