We present observations of SN 2021csp, a unique supernova (SN) which displays evidence for interaction with H- and He- poor circumstellar material (CSM) at early times. Using high-cadence spectroscopy taken over the first week after explosion, we show that the spectra of SN 2021csp are dominated by C III lines with a velocity of 1800 km s−1. We associate this emission with CSM lost by the progenitor prior to explosion. Subsequently, the SN displays narrow He lines before metamorphosing into a broad-lined Type Ic SN. We model the bolometric light curve of SN 2021csp, and show that it is consistent with the energetic (4×1051 erg) explosion of a stripped star, producing 0.4 M⊙ of 56Ni within a ∼1 M⊙ shell of CSM extending out to 400 R⊙.
@article{arxiv.2108.07278,
title = {SN 2021csp -- the explosion of a stripped envelope star within a H and He-poor circumstellar medium},
author = {Morgan Fraser and Maximilian D. Stritzinger and Sean J. Brennan and Andrea Pastorello and Yongzhi Cai and Anthony L. Piro and Chris Ashall and Peter Brown and Christopher R. Burns and Nancy Elias-Rosa and Rubina Kotak and Alexei V. Filippenko and L. Galbany and E. Y. Hsiao and Saurabh W. Jha and Andrea Reguitti and Ju-jia Zhang and Shane Moran and Nidia Morrell and B. J. Shappee and Lina Tomasella and J. P. Anderson and Tyler Barna and Paolo Ochner and M. M. Phillips and Michael Tucker and Xiaofeng Wang and E. Baron and Stefano Benetti and Melina C. Bersten and Thomas G. Brink and Yssavo Camacho-Neves and Scott Davis and Kyle G. Dettman and Gaston Folatelli and Claudia P. Gutierrez and Peter Hoflich and Thomas W. -S. Holoien and Erkki Kankare and Sahana Kumar and Jing Lu and Paolo Mazzali and Stefan Taubenberger and Samaporn Tinyanont and Hanindyo Kuncarayakti and Lindsey Kwok and Melissa Shahbandeh and Nicholas B. Suntzeff and Shengyu Yan and Yi Yang and WeiKang Zheng},
journal= {arXiv preprint arXiv:2108.07278},
year = {2021}
}