SN 2022xxf photometry and spectra

However, narrow emission lines (corresponding to ~1000-2500km/s) are present in the spectra from the time of the second rise, suggesting slower-moving circumstellar material (CSM). These lines are subtle, in comparison to the typical strong narrow lines of CSM-interacting SNe, for example, Type IIn, Ibn, and Icn, but some are readily noticeable at late times such as in MgI {lambda}5170 and [OI] {lambda}5577. Unusually, the near-infrared spectra show narrow line peaks in a number of features formed by ions of O and Mg.

We infer the presence of CSM that is free of H and He. We propose that the radiative energy from the ejecta-CSM interaction is a plausible explanation for the second LC hump. This interaction scenario is supported by the color evolution, which progresses to the blue as the light curve evolves along the second hump, and the slow second rise and subsequent rapid LC drop.

SN 2022xxf may be related to an emerging number of CSM-interacting SNe Ic, which show slow, peculiar LCs, blue colors, and subtle CSM interaction lines. The progenitor stars of these SNe likely experienced an episode of mass loss shortly prior to explosion consisting of H/He-free material. Description: The first observations of SN 2022xxf/ZTF22abnvurz with the Zwicky Transient Facility, and the Palomar Schmidt 48-inch (P48) Samuel Oschin telescope under the twilight survey, were made on October 18, 2022 (MJD^ZTF^_FirstDerection_=59870.53) in r-band, one day after the discovery.

The first spectrum of SN 2022xxf was obtained using the Hiroshima One-shot Wide-field Polarimeter (HOWPol) on the 1.5-m Kanata telescope at the Higashi-Hiroshima Observatory, Hiroshima University. Spectra and photometry data of SN 2022xxf.