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SN 2011hs: a fast and faint Type IIb supernova from a supergiant progenitor

Bufano, F, Pignata, G, Bersten, M, Mazzali, PA, Ryder, SD, Margutti, R, Milisavljevic, D, Morelli, L, Benetti, S, Cappellaro, E, Gonzalez-Gaitan, S, Romero-Canizales, C, Stritzinger, M, Walker, ES, Anderson, JP, Contreras, C, de Jaeger, T, Foerster, F, Gutierrez, C, Hamuy, M , Hsiao, E, Morrell, N, Olivares E, F, Paillas, E, Parker, S, Pian, E, Pickering, TE, Sanders, N, Stockdale, C, Turatto, M, Valenti, S, Fesen, RA, Maza, J, Nomoto, K, Phillips, MM and Soderberg, A (2014) SN 2011hs: a fast and faint Type IIb supernova from a supergiant progenitor. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 439 (2). pp. 1807-1828. ISSN 0035-8711

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Observations spanning a large wavelength range, from X-ray to radio, of the Type IIb supernova (SN) 2011hs are presented, covering its evolution during the first year after explosion. The optical light curve presents a narrower shape and a fainter luminosity at peak than previously observed for Type IIb SNe. High expansion velocities are measured from the broad absorption H I and He I lines. From the comparison of the bolometric light curve and the time evolution of the photospheric velocities with hydrodynamical models, we found that SN 2011hs is consistent with the explosion of a 3–4 M⊙ He-core progenitor star, corresponding to a main-sequence mass of 12–15 M⊙, that ejected a mass of 56Ni of about 0.04 M⊙, with an energy of E = 8.5 × 1050 ERG. Such a low-mass progenitor scenario is in full agreement with the modelling of the nebular spectrum taken at ∼215 d from maximum. From the modelling of the adiabatic cooling phase, we infer a progenitor radius of ≈500–600 R⊙, clearly pointing to an extended progenitor star. The radio light curve of SN 2011hs yields a peak luminosity similar to that of SN 1993J, but with a higher mass-loss rate and a wind density possibly more similar to that of SN 2001ig. Although no significant deviations from a smooth decline have been found in the radio light curves, we cannot rule out the presence of a binary companion star.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record MNRAS (April 01, 2014) 439 (2): 1807-1828 is available online at: http://dx.doi.org/10.1093/mnras/stu065
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
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Date Deposited: 08 Feb 2016 11:03
Last Modified: 17 May 2022 09:48
DOI or ID number: 10.1093/mnras/stu065
URI: https://researchonline.ljmu.ac.uk/id/eprint/2858
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