The Early Light Curve of the Type Ia Supernova 2021hpr in NGC 3147: Progenitor Constraints with the Companion Interaction Model
Wheeler, J. Craig; Im, Myungshin; Kim, Dohyeong; Sung, Hyun-Il; Lim, Gu; Paek, Gregory S. H.; Yoon, Sung-Chul; Choi, Changsu; Kim, Sophia; Thomas, Benjamin P.; Vinkó, Jozsef; Seo, Jinguk; Kang, Wonseok; Kim, Taewoo; Kim, Yonggi; Yoon, Joh-Na; Kim, Haeun; Kim, Jeongmook; Bae, Hana; Ehgamberdiev, Shuhrat; Burhonov, Otabek; Mirzaqulov, Davron
South Korea, Republic of Korea, United States, Hungary, Uzbekistan
Abstract
The progenitor system of Type Ia supernovae (SNe Ia) is expected to be a close binary system consisting of a carbon/oxygen white dwarf (WD) and a nondegenerate star or another WD. Here, we present results from high-cadence monitoring observations of SN 2021hpr in a spiral galaxy, NGC 3147, and constraints on the progenitor system based on its early multicolor light-curve data. First, we classify SN 2021hpr as a normal SN Ia from its long-term photometric and spectroscopic data. More interestingly, we found a significant "early excess" in the light curve over a simple power-law ~t 2 evolution. The early light curve evolves from blue to red to blue during the first week. To explain this, we fitted the early part of the BVRI-band light curves with a two-component model consisting of ejecta-companion interaction and a simple power-law model. The early excess and its color can be explained by shock-cooling emission due to a companion star having a radius of 8.84 ± 0.58 R ⊙. We also examined Hubble Space Telescope preexplosion images, finding no detection of a progenitor candidate, consistent with the above result. However, we could not detect signs of a significant amount of stripped mass from a nondegenerate companion star (≲0.003 M ⊙ for Hα emission). The early excess light in the multiband light curve supports a nondegenerate companion in the progenitor system of SN 2021hpr. At the same time, the nondetection of emission lines opens the door for other methods to explain this event.