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Abstract We report the results of a rapid follow-up campaign on the Type IIb supernova (SN) 2022hnt. We present a daily, multiband, photometric follow-up using the Las Cumbres Observatory, the Zwicky Transient Facility, the orbiting Swift observatory, and the Asteroid Terrestrial-impact Last Alert System. A distinctive feature in the light curve of SN 2022hnt and other IIb SNe is an early narrow peak prior to the56Ni peak caused by rapid shock cooling of the hydrogen envelope, which can serve as an important probe of the properties of the massive progenitor star in the moments before explosion. Using SN 2022hnt as a case study, we demonstrate a framework of considerations for the application of shock cooling models to type IIb SNe, outlining a consistent procedure for future surveys of Type IIb SNe progenitor and explosion properties. We fit several recent models of shock-cooling emission and obtain progenitor radii between ∼50 and ∼100R⊙, as well as hydrogen-enriched envelope masses between ∼0.01 and ∼0.1M⊙, both consistent with values for other IIb SNe. One of these models is the model of J. Morag et al., marking the first time this model has been applied to a Type IIb SN. Finally, we evaluate contrasting predictions between shock-cooling models to construct a fiducial parameter set that can be used for comparison to other SNe.
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This content will become publicly available on June 1, 2027
SN 2024iss: A double-peaked Type IIb supernova with evidence of circumstellar interaction
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 theV-band light curve reachedMV = −17.33 ± 0.26 mag, while the56Ni-powered second peak attainedMV = −17.43 ± 0.26 mag. Early spectra show a photospheric velocity of approximately 19 400 km s−1at 3.82 days from the HαP 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 typical56Ni 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 × 10−5M⊙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.
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- Award ID(s):
- 2407566
- PAR ID:
- 10706396
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Astronomy & Astrophysics
- Date Published:
- Journal Name:
- Astronomy & Astrophysics
- Volume:
- 710
- ISSN:
- 0004-6361
- Page Range / eLocation ID:
- A33
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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