J/A+A/703/A177ivo://CDS.VizieR/J/A+A/703/A177CDSTartaglia L.Valerin G.Pastorello A.Reguitti A.Benetti S.,Tomasella L.Ochner P.Brocato E.Condo L.De Luise F.Onori F.,Salmaso I.2026-03-02T06:25:50Z2025-11-24T09:22:39ZCDS support team

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

cds-question@unistra.frsupernovaephotometryvisible-astronomyultraviolet-astronomyspectroscopyinfrared-astronomyIn this paper we analyse the spectro-photometric properties of the Type II supernova SN 2024bch, exploded in NGC 3206 at a distance of 19.9Mpc. Its early spectra are characterised by narrow high-ionisation emission lines, often interpreted as signatures of ongoing interaction between rapidly expanding ejecta and a confined dense circumstellar medium. However, we provide a model for the bolometric light curve of the transient that does not require sources of energy different than radioactive decays and H recombination. Our model can reproduce the bolometric light curve of SN 2024bch adopting an ejected mass of M_bulk_~+5M_{sun}_ surrounded by an extended envelope of only 0.2M_{sun}_ with an outer radius R_env_=7.0x10^13^cm. An accurate modelling focused on the radioactive part of the light curve, which accounts for incomplete gamma-ray trapping, gives a ^56^Ni mass of 0.048M_{sun}_. We propose narrow lines to be powered by Bowen fluorescence induced by scattering of HeII Ly-alpha photons, resulting in the emission of high-ionisation resonance lines. Simple light travel time calculations based on the maximum phase of the narrow emission lines place the inner radius of the H-rich, un-shocked shell at a radius ~=4.4x10^15^cm$, compatible with an absence of ejecta-CSM interaction during the first weeks of evolution. Possible signatures of interaction appear only ~69-days after explosion, although the resulting conversion of kinetic energy into radiation does not seem to contribute significantly to the total luminosity of the transient.2025A&A...703A.177Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/703/A177CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/703/A177https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/703/A177http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/703/A177https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/703/A177https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/703/A177http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/703/A177GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/703/A177/list (List of fits spectra)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/703/A177/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/703/A177/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/703/A177/list?GETtext/xml+votable180.050000true155.4572556.92791670.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/703/A1776/6063https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/703/A177?format=asciiUVOpticalInfrareddefaultJ/A+A/703/A177/lcUV+optical light curves of SN 2024bch (Figures 2, 7, 8 and 11)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateUT date of observation (YYYY/MM/DD)'Y:M:D'time.epoch;obsnullableMJDModified Julian Date of the observationdtime.epochdoubleFilterFilter (BV UsBsVs ugriz UVM2 UVW1 UVW2)meta.id;instr.filtercharSystem[ab vega] Photometric system of the calibrationmeta.notecharl_magLimit flag on magmeta.code.errorcharmagMagnitude in Filtermagphot.magfloate_magError on mag in Filtermagstat.error;phot.magcharInstTelescope and instrument usedinstr.setupcharJ/A+A/703/A177/bolParameters of the blackbody fit to the SED (table 3)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPhaseDays from explosion (JD-2460338.0)dtime.phasefloatTempTemperature of the blackbodyKphys.temperatureinte_TempError on tempKstat.errorintRadRadius of the blackbody1e+14cmphys.size.radiusfloate_RadError on rad1e+14cmstat.errorfloatLumBolometric luminosity (in 10^+42^erg/s)1e+35Wphys.luminosityfloate_LumError on lum (in 10^+42^erg/s)1e+35Wstat.errorfloatJ/A+A/703/A177/listList of fits spectrarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNy? Number of pixels along Y-axismeta.numberintnullableObs.dateObservation datestime.epoch;obsnullableblambdaLower value of wavelength interval0.1nmem.wlfloatBlambdaUpper value of wavelength interval0.1nmem.wldoubledlambdaWavelength resolution0.1nmspect.resolutiondoublesizeSize of FITS fileKibytephys.size;meta.fitsintspShow the spectrummeta.ref.urlcharFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitschar