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The dusty aftermath of SN Hunt 248: merger-burst remnant?

Mauerhan, Jon C. and Van Dyk, Schuyler D. and Johansson, Joel and Fox, Ori D. and Filippenko, Alexei V. and Graham, Melissa L. (2018) The dusty aftermath of SN Hunt 248: merger-burst remnant? Monthly Notices of the Royal Astronomical Society, 473 (3). pp. 3765-3775. ISSN 0035-8711. https://resolver.caltech.edu/CaltechAUTHORS:20180216-082056376

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Abstract

SN Hunt 248 was classified as a non-terminal eruption (a supernova ‘impostor’) from a directly identified and highly variable cool hypergiant star. The 2014 outburst achieved peak luminosity equivalent to that of the historic eruption of luminous blue variable (LBV) η Car, and exhibited a multipeaked optical light curve which rapidly faded after ∼100  d. We report ultraviolet (UV) through optical observations of SN Hunt 248 with the Hubble Space Telescope (HST) about 1 yr after the outburst, and mid-infrared observations with the Spitzer Space Telescope before the burst and in decline. The HST data reveal a source which is a factor of ∼10 dimmer in apparent brightness than the faintest available measurement of the precursor star. The UV–optical spectral energy distribution (SED) requires a strong Balmer continuum, consistent with a hot B4–B5 photosphere attenuated by grey circumstellar extinction. Substantial mid-infrared excess of the source is consistent with thermal emission from hot dust with a mass of ∼10^(−6)–10^(−5) M_⊙ and a geometric extent which is comparable to the expansion radius of the ejecta from the 2014 event. SED modelling indicates that the dust consists of relatively large grains ( > 0.3 μm), which could be related to the grey circumstellar extinction which we infer for the UV–optical counterpart. Revised analysis of the precursor photometry is also consistent with grey extinction by circumstellar dust, and suggests that the initial mass of the star could be twice as large as previously estimated (nearly ∼ 60 M_⊙). Re-analysis of the earlier outburst data shows that the peak luminosity and outflow velocity of the eruption are consistent with a trend exhibited by stellar merger candidates, prompting speculation that SN Hunt 248 may also have stemmed from a massive stellar merger or common-envelope ejection.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/stx2500DOIArticle
https://academic.oup.com/mnras/article/473/3/3765/4265329PublisherArticle
https://arxiv.org/abs/1702.00430arXivDiscussion Paper
ORCID:
AuthorORCID
Van Dyk, Schuyler D.0000-0001-9038-9950
Fox, Ori D.0000-0003-2238-1572
Filippenko, Alexei V.0000-0003-3460-0103
Graham, Melissa L.0000-0002-9154-3136
Additional Information:© 2018 Published by Oxford University Press. Accepted 2017 September 25. Received 2017 August 4; in original form 2017 January 31. This work is based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555. This work is also based in part on observations and archival data obtained with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA; support was provided by NASA through an award issued by JPL/Caltech. AVF's supernova group is also supported by Gary & Cynthia Bengier, the Richard & Rhoda Goldman Fund, the Christopher R. Redlich Fund, the TABASGO Foundation and the Miller Institute for Basic Research in Science (U.C. Berkeley).
Group:Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
NASANAS5-26555
NASA/JPL/CaltechUNSPECIFIED
Gary and Cynthia BengierUNSPECIFIED
Richard and Rhoda Goldman FundUNSPECIFIED
Christopher R. Redlich FundUNSPECIFIED
TABASGO FoundationUNSPECIFIED
Miller Institute for Basic Research in ScienceUNSPECIFIED
Subject Keywords:stars: evolution, supernovae: general, supernovae: individual: SN Hunt 248, stars: winds, outflows
Issue or Number:3
Record Number:CaltechAUTHORS:20180216-082056376
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180216-082056376
Official Citation:Jon C. Mauerhan, Schuyler D. Van Dyk, Joel Johansson, Ori D. Fox, Alexei V. Filippenko, Melissa L. Graham; The dusty aftermath of SN Hunt 248: merger-burst remnant?, Monthly Notices of the Royal Astronomical Society, Volume 473, Issue 3, 21 January 2018, Pages 3765–3775, https://doi.org/10.1093/mnras/stx2500
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84860
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:20 Feb 2018 21:09
Last Modified:09 Mar 2020 13:18

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