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SN 2020acat: an energetic fast rising Type IIb supernova

Medler, K., Mazzali, P. A., Teffs, J., Ashall, C., Anderson, J. P., Arcavi, I., Benetti, S., Bostroem, K. A., Burke, J., Cai, Y.-Z., Charalampopoulos, P., Elias-Rosa, N., Ergon, M., Galbany, L., Gromadzki, M., Hiramatsu, D., Howell, D. A., Inserra, C. ORCID:, Lundqvist, P., McCully, C., Müller-Bravo, T., Newsome, M., Nicholl, M., Padilla Gonzalez, E., Paraskeva, E., Pastorello, A., Pellegrino, C., Pessi, P. J., Reguitti, A., Reynolds, T. M., Roy, R., Terreran, G., Tomasella, L. and Young, D. R. 2022. SN 2020acat: an energetic fast rising Type IIb supernova. Monthly Notices of the Royal Astronomical Society 513 (4) , 5540–5558. 10.1093/mnras/stac1192

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The ultraviolet (UV) and near-infrared (NIR) photometric and optical spectroscopic observations of SN 2020acat covering ∼250 d after explosion are presented here. Using the fast rising photometric observations, spanning from the UV to NIR wavelengths, a pseudo-bolometric light curve was constructed and compared to several other well-observed Type IIb supernovae (SNe IIb). SN 2020acat displayed a very short rise time reaching a peak luminosity of Log10(L)=42.49±0.17ergs−1 in only ∼14.6 ± 0.3 d. From modelling of the pseudo-bolometric light curve, we estimated a total mass of 56Ni synthesized by SN 2020acat of MNi = 0.13 ± 0.03 M⊙, with an ejecta mass of Mej = 2.3 ± 0.4 M⊙ and a kinetic energy of Ek = 1.2 ± 0.3 × 1051 erg. The optical spectra of SN 2020acat display hydrogen signatures well into the transitional period (≳ 100 d), between the photospheric and the nebular phases. The spectra also display a strong feature around 4900  Å that cannot be solely accounted for by the presence of the Fe II 5018 line. We suggest that the Fe II feature was augmented by He I 5016 and possibly by the presence of N II 5005. From both photometric and spectroscopic analysis, we inferred that the progenitor of SN 2020acat was an intermediate-mass compact star with an MZAMS of 15–20 M⊙.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Additional Information: This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommonsorg/licenses/by/4.0/)
Publisher: Royal Astronomical Society
ISSN: 0035-8711
Date of First Compliant Deposit: 26 August 2022
Date of Acceptance: 25 April 2022
Last Modified: 10 May 2023 17:49

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