Progenitor and close-in circumstellar medium of type II supernova 2020fqv from high-cadence photometry and ultra-rapid UV spectroscopy

Tinyanont, Samaporn and Ridden-Harper, R and Foley, R J and Morozova, V and Kilpatrick, C D and Dimitriadis, G and DeMarchi, L and Gagliano, A and Jacobson-Galán, W V and Messick, A and Pierel, J D R and Piro, A L and Ramirez-Ruiz, E and Siebert, M R and Chambers, K C and Clever, K E and Coulter, D A and De, K and Hankins, M and Hung, T and Jha, S W and Jimenez Angel, C E and Jones, D O and Kasliwal, M M and Lin, C-C and Marques-Chaves, R and Margutti, R and Moore, A and Pérez-Fournon, I and Poidevin, F and Rest, A and Shirley, R and Smith, C S and Strasburger, E and Swift, J J and Wainscoat, R J and Wang, Q and Zenati, Y (2022) Progenitor and close-in circumstellar medium of type II supernova 2020fqv from high-cadence photometry and ultra-rapid UV spectroscopy. Monthly Notices of the Royal Astronomical Society, 512 (2). pp. 2777-2797. ISSN 0035-8711

Abstract

We present observations of SN 2020fqv, a Virgo-cluster type II core-collapse supernova (CCSN) with a high temporal resolution light curve from the Transiting Exoplanet Survey Satellite (TESS) covering the time of explosion; ultraviolet (UV) spectroscopy from the Hubble Space Telescope (HST) starting 3.3 d post-explosion; ground-based spectroscopic observations starting 1.1 d post-explosion; along with extensive photometric observations. Massive stars have complicated mass-loss histories leading up to their death as CCSNe, creating circumstellar medium (CSM) with which the SNe interact. Observations during the first few days post-explosion can provide important information about the mass-loss rate during the late stages of stellar evolution. Model fits to the quasi-bolometric light curve of SN 2020fqv reveal 0.23 M⊙ of CSM confined within 1450 R⊙ (1014 cm) from its progenitor star. Early spectra (<4 d post-explosion), both from HST and ground-based observatories, show emission features from high-ionization metal species from the outer, optically thin part of this CSM. We find that the CSM is consistent with an eruption caused by the injection of ∼5 × 1046 erg into the stellar envelope ∼300 d pre-explosion, potentially from a nuclear burning instability at the onset of oxygen burning. Light-curve fitting, nebular spectroscopy, and pre-explosion HST imaging consistently point to a red supergiant (RSG) progenitor with MZAMS ≈ 13.5-15 M⊙, typical for SN II progenitor stars. This finding demonstrates that a typical RSG, like the progenitor of SN 2020fqv, has a complicated mass-loss history immediately before core collapse.