SN 2024iss: A double-peaked Type IIb supernova with evidence of circumstellar interaction

Le résumé fourni par la source

Aims. We present optical, ultraviolet, and X-ray observations of supernova (SN) 2024iss, a Type IIb SN that shows a prominent double-peaked light curve. Methods. We modeled the first peak with a semianalytical shock-cooling model and the X-ray emission with a free-free model. We also compared the envelope radius and mass-loss rate with those of other Type IIb SNe to explore the relationships between the progenitor envelope and the circumstellar material. Results. The shock-cooling peak in the V-band light curve reached MV = −17.33 ± 0.26 mag, while the 56Ni-powered second peak attained MV = −17.43 ± 0.26 mag. Early spectra show a photospheric velocity of approximately 19 400 km s−1 at 3.82 days from the Hα P Cygni profile. The Balmer lines persist for at least more than 87 days after the explosion, which is characteristic of hydrogen-rich ejecta. Modeling the first light-curve peak with the shock-cooling model suggests an extended hydrogen envelope with a mass of 0.11 ± 0.04 M⊙ and a radius of 244 ± 43 R⊙. Fitting the second light-curve peak with an Arnett-like model indicates a typical 56Ni mass of 0.117 ± 0.013 M⊙ and a relatively low ejecta mass of 1.27 ± 0.34 M⊙. X-ray observations revealed bright thermal bremsstrahlung emission and indicate a mass-loss rate of 1.6 × 10−5 M⊙ yr−1, which is similar to that of SN 1993J. Conclusions. Supernova 2024iss occupies a transitional position between the two subclasses of extended and compact Type IIb SNe. Its envelope radius and preexplosion mass-loss rate appear to be consistent with the correlation observed in the broader sample. The observational properties of SN 2024iss are compatible with a binary-interaction scenario being the dominant mechanism for envelope stripping.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.