J/A+A/704/A135ivo://CDS.VizieR/J/A+A/704/A135CDSTsalapatas K.Sollerman J.Chiba R.Kool E.Johansson J.Rosswog S.,Schulze S.Moriya T.J.Andreoni I.Brink T.G.Chen T.X.Covarrubias S.,De K.Dimitriadis G.Filippenko A.V.Fremling C.Gangopadhyay A.,Maguire K.Mo G.Sharma Y.Sravan N.Terwel J.H.Yang Y.2026-03-02T06:25:50Z2025-12-05T09:20:59ZCDS support team

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

cds-question@unistra.frsupernovaeinfrared-photometryvisible-astronomybroad-band-photometryIdentifying the progenitors of thermonuclear supernovae (Type Ia supernovae; SNe Ia) remains a key objective in contemporary astronomy. The rare subclass of SNe Ia-CSM that interacts with circumstellar material (CSM) allows for studies of the progenitor's environment before explosion, and generally favours single-degenerate progenitor channels. The case of SN Ia-CSM PTF11kx clearly connected thermonuclear explosions with hydrogen-rich CSM-interacting events, and the more recent SN 2020eyj connected SNe Ia with helium-rich companion progenitors. Both of these objects displayed delayed CSM interaction which established their thermonuclear nature. Here we present a study of SN2020aeuh, a Type Ia-CSM with delayed interaction. We analyse photometric and spectroscopic data that monitor the evolution of SN2020aeuh and compare its properties with those of peculiar SNe Ia and core-collapse SNe. At early times, the evolution of SN2020aeuh resembles a slightly overluminous SN~Ia. Later, the interaction-dominated spectra develop the same pseudocontinuum seen in Type Ia-CSM PTF11kx and SN 2020eyj. However, the later-time spectra of SN2020aeuh lack hydrogen and helium narrow lines. Instead, a few narrow lines could be attributed to carbon and oxygen. We fit the pseudobolometric light curve with a CSM-interaction model, yielding a CSM mass of 1-2M_{sun}_. We propose that SN2020aeuh was a Type Ia supernova that eventually interacted with a dense medium which was deficient in both hydrogen and helium. Whereas previous SNe Ia-CSM constitute our best evidence for nondegenerate companion progenitors, the CSM around SN2020aeuh is more difficult to understand. We include a hydrodynamical simulation for a double-degenerate dynamical collision to showcase that such a progenitor scenario could produce significant amounts of hydrogen-poor CSM, although likely not as much as the inferred CSM mass around SN2020aeuh. It is clear that SN2020aeuh challenges current models for stellar evolution leading up to a SN Ia explosion.2025A&A...704A.135Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/704/A135CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/704/A135https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/704/A135http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/704/A135https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/704/A135https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/704/A135http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/704/A135GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/A+A/704/A135/tablea1Optical photometry of SN 2020aeuhrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDTime in MJDdtime.epochdoublePhasePhase relative to first detectiondtime.phasefloatFilter[gri co] Optical Filtersinstr.bandpasscharmag? Magnitude in Filter in the AB systemmagphot.magfloatnullablee_mag? Magnitude in Filter errormagstat.error;phot.magfloatnullablemaglim? Limiting magnitudemagphot.magfloatnullableTelTelescope + instrumentinstrchar