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Published April 1, 2022 | Accepted Version + Published
Journal Article Open

Unveiling the Nature of SN 2011fh: A Young and Massive Star Gives Rise to a Luminous SN 2009ip−like Event

Abstract

In recent years, many Type IIn supernovae have been found to share striking similarities with the peculiar SN 2009ip, whose true nature is still under debate. Here, we present 10 yr of observations of SN 2011fh, an interacting transient with spectroscopic and photometric similarities to SN 2009ip. SN 2011fh had an M_r ∼ −16 mag brightening event, followed by a brighter M_r ∼ −18 mag luminous outburst in 2011 August. The spectra of SN 2011fh are dominated by narrow to intermediate Balmer emission lines throughout its evolution, with P Cygni profiles indicating fast-moving material at ∼6400 km s⁻¹. HST/WFC3 observations from 2016 October revealed a bright source with M_(F814W) ≈ −13.3 mag, indicating that we are seeing the ongoing interaction of the ejecta with the circumstellar material or that the star might be going through an eruptive phase five years after the luminous outburst of 2011. Using HST photometry of the stellar cluster around SN 2011fh, we estimated an age of ∼4.5 Myr for the progenitor, which implies a stellar mass of ∼60 M⊙, using single-star evolution models, or a mass range of 35–80 M⊙, considering a binary system. We also show that the progenitor of SN 2011fh exceeded the classical Eddington limit by a large factor in the months preceding the luminous outburst of 2011, suggesting strong super-Eddington winds as a possible mechanism for the observed mass loss. These findings favor an energetic outburst in a young and massive star, possibly a luminous blue variable.

Additional Information

© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 October 14; revised 2022 January 3; accepted 2022 January 16; published 2022 April 4. We would like to thank Andrea Pastorello and Melissa Graham for kindly sharing their data on SN 2016bdu, SN 2018cnf, and SN 2009ip. We thank the Carnegie Supernova Project-II for obtaining several photometric observations presented in the paper, and in particular Carlos Contreras, Mark Phillips, Nidia Morrell, and Eric Hsiao. T.P. is supported by CONICYT's Programa de Astronomía through the ALMA-CONICYT 2019 grant 31190017. Support for J.L.P. is provided in part by ANID through the Fondecyt regular grant 1191038 and through the Millennium Science Initiative grant ICN120 09, awarded to The Millennium Institute of Astrophysics, MAS. C.S.K. is supported by NSF grants AST-1814440 and AST-1907570. HFS acknowledges the support of the Marsden Fund Council managed through Royal Society Te Aparangi. This paper includes optical and NIR photometry obtained by the Carnegie Supernova Project, which was generously supported by NSF grants AST-1008343, AST-1613426, AST-1613455, and AST-1613472. Software: HOKI (Stevance et al. 2020a, 2020b), BPASS (Eldridge et al. 2017; Stanway & Eldridge 2018), FIREHOSE (Simcoe et al. 2013), IRAF (Tody 1986, 1993), Astropy (Astropy Collaboration et al. 2013, 2018), Photutils (Bradley et al. 2019), PYPHOT (https://mfouesneau.github.io/docs/pyphot/), DUSTY (Ivezic & Elitzur 1997), DOLPHOT (Dolphin 2016), SUPERBOL (Version 1.7; Nicholl 2018), ifuanalysis (https://ifuanal.readthedocs.io/en/latest/index.html), STARLIGHT (Cid Fernandes et al. 2005; Mateus et al. 2006; Asari et al. 2007).

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Published - Pessi_2022_ApJ_928_138.pdf

Accepted Version - 2110.09546.pdf

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Additional details

Created:
August 22, 2023
Modified:
October 24, 2023