J/ApJ/910/151ivo://CDS.VizieR/J/ApJ/910/151doi:10.26093/cds/vizier.19100151CDSMoon D.-S.Ni Y.QiDrout M.R.Gonzalez-Gaitan S.Afsariardchi N.,Park H.S.Lee Y.Kim S.C.Antoniadis J.Kim D.-J.Lee Y.2022-11-25T13:34:09Z2022-10-25T12:25:05ZCDS support team

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

cds-question@unistra.frsupernovaeinfrared-photometryvisible-astronomybroad-band-photometryWe report the early discovery and multicolor (BVI) high-cadence light-curve analyses of the rapidly declining sub-Chandrasekhar Type Ia supernova KSP-OT-201509b (= AT 2015cx) from the KMTNet Supernova Program. The Phillips and color stretch parameters of KSP-OT-201509b are {Delta}M_B,15_~1.62mag and s_BV_~0.54, respectively, at an inferred redshift of 0.072. These, together with other measured parameters (such as the strength of the secondary I-band peak, colors, and luminosity), identify the source to be a rapidly declining Type Ia of a transitional nature that is closer to Branch-normal than 91bg-like. Its early light-curve evolution and bolometric luminosity are consistent with those of homologously expanding ejecta powered by radioactive decay and a Type Ia SN explosion with 0.32+/-0.01M_{sun}_ of synthesized ^56^Ni mass, 0.84+/-0.12M_{sun}_ of ejecta mass, and (0.61+/-0.14)x10^51^erg of ejecta kinetic energy. While its B-V and V-I colors evolve largely synchronously with the changes in the I-band light curve, as found in other supernovae, we also find the presence of an early redward evolution in V-I prior to -10 days since peak. The bolometric light curve of the source is compatible with a stratified ^56^Ni distribution extended to shallow layers of the exploding progenitor. Comparisons between the observed light curves and those predicted from ejecta-companion interactions clearly disfavor Roche lobe-filling companion stars at large separation distances, thus supporting a double-degenerate scenario for its origin. The lack of any apparent host galaxy in our deep stack images reaching a sensitivity limit of ~28mag/arcsec^2^ makes KSP-OT-201509b a hostless Type Ia supernova and offers new insights into supernova host galaxy environments.2021ApJ...910..151Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/910/151CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/MNRAS/383/1485 : BVRI light curves of SN 2003jd (Valenti+, 2008)J/AJ/139/519 : Carnegie supernova project. SNe Ia (Contreras+, 2010)J/MNRAS/412/1441 : SNe luminosity functions (Li+, 2011)J/MNRAS/448/1345 : YJK for Type Ia supernovae (Dhawan+, 2015)J/A+A/578/A9 : Optical and NIR spectra of SN iPTF13ebh (Hsiao+, 2015)J/ApJ/826/56 : HST/WFC3 obs. of Cepheids in SN Ia host gal. (Riess+, 2016)J/ApJ/826/144 : Follow-up observations of SNIa ASASSN-14lp (Shappee+, 2016)J/ApJ/836/60 : Bgri light curves of PTF11kmb and PTF12bho (Lunnan+, 2017)J/ApJ/869/56 : Updated calibration of CSP-I SNe Ia sample (Burns+, 2018)J/ApJ/881/22 : BVI phot. of TypeII SN KSP-SN-2016kf (Afsariardchi+, 2019)J/ApJ/870/L1 : K2 obs. of type Ia supernova SN 2018oh (Dimitriadis+, 2019)J/A+A/627/A174 : Early light curve of SN 2013gy (Holmbo+, 2019)J/MNRAS/483/628 : SN Ia properties using bolometric LCs (Scalzo+, 2019)J/ApJ/870/13 : K2 LC alternative analysis of ASASSN-18bt (Shappee+, 2019)J/A+A/634/A37 : TURTLS Light curves of ^56^Ni distributions (Magee+, 2020)J/ApJ/898/56 : UVOT, ZTF gri LCs & sp. of the SN Ia 2019yvq (Miller+, 2020)J/ApJ/908/51 : TESS early LCs of type Ia Supernovae (Fausnaugh+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/910/151https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/910/151http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/910/151https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/910/151https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/910/151http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/910/151GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/910/151/table1Observed KMTNet BVi magnitudes of KSP-OT-201509brecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[57289.89/57359.48] Time, Modified Julian Date (JD-2400000.5)dtime.epochdoubleomag[18.37/22.18] Observed magnitude in Filt (1)magphot.magfloate_omag[0.016/0.5] Uncertainty in omagmagstat.error;phot.magfloatFilt[BVi] Bandmeta.code;instr.filterchar