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The Blue Supergiant Progenitor of the Supernova Imposter AT 2019krl

Andrews, Jennifer E. and Jencson, Jacob E. and Van Dyk, Schuyler D. and Smith, Nathan and Neustadt, Jack M. M. and Sand, David J. and Kreckel, K. and Kochanek, C. S. and Valenti, S. and Strader, Jay and Bersten, M. C. and Blanc, Guillermo A. and Bostroem, K. Azalee and Brink, Thomas G. and Emsellem, Eric and Filippenko, Alexei V. and Folatelli, Gastón and Kasliwal, Mansi M. and Masci, Frank J. and McElroy, Rebecca and Milisavljevic, Dan and Santoro, Francesco and Szalai, Tamás (2021) The Blue Supergiant Progenitor of the Supernova Imposter AT 2019krl. Astrophysical Journal, 917 (2). Art. No. 63. ISSN 0004-637X. doi:10.3847/1538-4357/ac09e1. https://resolver.caltech.edu/CaltechAUTHORS:20210205-093220958

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Abstract

Extensive archival Hubble Space Telescope, Spitzer Space Telescope, and Large Binocular Telescope imaging of the recent intermediate-luminosity transient, AT 2019krl in M74, reveal a bright optical and mid-infrared progenitor star. While the optical peak of the event was missed, a peak was detected in the infrared with an absolute magnitude of M_(4.5 μm) = −18.4 mag, leading us to infer a visual-wavelength peak absolute magnitude of −13.5 to −14.5. The pre-discovery light curve indicated no outbursts over the previous 16 yr. The colors, magnitudes, and inferred temperatures of the progenitor best match a 13–14 M_⊙ yellow or blue supergiant (BSG) if only foreground extinction is taken into account, or a hotter and more massive star if any additional local extinction is included. A pre-eruption spectrum of the star reveals strong Hα and [N ii] emission with wings extending to ±2000 km s⁻¹. The post-eruption spectrum is fairly flat and featureless with only Hα, Na i D, [Ca ii], and the Ca ii triplet in emission. As in many previous intermediate-luminosity transients, AT 2019krl shows remarkable observational similarities to luminous blue variable (LBV) giant eruptions, SN 2008S-like events, and massive-star mergers. However, the information about the pre-eruption star favors either a relatively unobscured BSG or a more extinguished LBV with M > 20 M_⊙ likely viewed pole-on.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/ac09e1DOIArticle
https://arxiv.org/abs/2009.13541arXivDiscussion Paper
ORCID:
AuthorORCID
Andrews, Jennifer E.0000-0003-0123-0062
Jencson, Jacob E.0000-0001-5754-4007
Van Dyk, Schuyler D.0000-0001-9038-9950
Smith, Nathan0000-0001-5510-2424
Neustadt, Jack M. M.0000-0001-7351-2531
Sand, David J.0000-0003-4102-380X
Kreckel, K.0000-0001-6551-3091
Kochanek, C. S.0000-0001-6017-2961
Valenti, S.0000-0001-8818-0795
Strader, Jay0000-0002-1468-9668
Bersten, M. C.0000-0002-6991-0550
Blanc, Guillermo A.0000-0003-4218-3944
Bostroem, K. Azalee0000-0002-4924-444X
Brink, Thomas G.0000-0001-5955-2502
Emsellem, Eric0000-0002-6155-7166
Filippenko, Alexei V.0000-0003-3460-0103
Folatelli, Gastón0000-0001-5247-1486
Kasliwal, Mansi M.0000-0002-5619-4938
Masci, Frank J.0000-0002-8532-9395
McElroy, Rebecca0000-0003-2290-7060
Milisavljevic, Dan0000-0002-0763-3885
Santoro, Francesco0000-0002-6363-9851
Szalai, Tamás0000-0003-4610-1117
Alternate Title:The progenitor of the supernova imposter AT 2019krl: a SN 2008S-like transient from a blue supergiant
Additional Information:© 2021. The American Astronomical Society. Received 2020 September 26; revised 2021 May 25; accepted 2021 June 8; published 2021 August 17. We thank the referees for comments that helped us improve this paper, as well as the staffs of the observatories where data were obtained. J.E.A. and N.S. receive support from National Science Foundation (NSF) grant AST-1515559. Research by D.J.S. is supported by NSF grants AST-1821967, 182197, 1813708, 1813466, and 1908972, as well as by the Heising-Simons Foundation under grant #2020-1864. Research by S.V. is supported by NSF grant AST-1813176. K.K. gratefully acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) in the form of an Emmy Noether Research Group (grant number KR4598/2-1). TS is supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences, by the New National Excellence Program (UNKP-20-5) of the Ministry of Technology and Innovation of Hungary, by the GINOP-2-3-2-15-2016-00033 project of the National Research, Development and Innovation Office of Hungary (NKFIH) funded by the European Union, and by NKFIH/OTKA FK-134432 grant. A.V.F.'s group received funding from NASA/HST grants GO-14668, GO-15166, and AR-14295 from the Space Telescope Science Institute (STScI), as well as from the TABASGO Foundation, the Christopher J. Redlich Fund, and the Miller Institute for Basic Research in Science (U.C. Berkeley; A.V.F. is a Miller Senior Fellow). Support for HST program GO-15151 was provided by NASA through a grant from STScI. Some of the data reported herein were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. Research at Lick Observatory is partially supported by a generous gift from Google. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from MAST at STScI. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under © 2021. The American Astronomical Society. Received 2020 September 26; revised 2021 May 25; accepted 2021 June 8; published 2021 August 17. We thank the referees for comments that helped us improve this paper, as well as the staffs of the observatories where data were obtained. J.E.A. and N.S. receive support from National Science Foundation (NSF) grant AST-1515559. Research by D.J.S. is supported by NSF grants AST-1821967, 182197, 1813708, 1813466, and 1908972, as well as by the Heising-Simons Foundation under grant #2020-1864. Research by S.V. is supported by NSF grant AST-1813176. K.K. gratefully acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) in the form of an Emmy Noether Research Group (grant number KR4598/2-1). TS is supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences, by the New National Excellence Program (UNKP-20-5) of the Ministry of Technology and Innovation of Hungary, by the GINOP-2-3-2-15-2016-00033 project of the National Research, Development and Innovation Office of Hungary (NKFIH) funded by the European Union, and by NKFIH/OTKA FK-134432 grant. A.V.F.'s group received funding from NASA/HST grants GO-14668, GO-15166, and AR-14295 from the Space Telescope Science Institute (STScI), as well as from the TABASGO Foundation, the Christopher J. Redlich Fund, and the Miller Institute for Basic Research in Science (U.C. Berkeley; A.V.F. is a Miller Senior Fellow). Support for HST program GO-15151 was provided by NASA through a grant from STScI. Some of the data reported herein were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. Research at Lick Observatory is partially supported by a generous gift from Google. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from MAST at STScI. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX13AC07G and by other grants and contracts. This work is based in part on 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. Based in part on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, Inovações e Comunicações (MCTIC) do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU). Based in part on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program ID 098.C-0484(A). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA; the Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facilities: HST (ACS - , WFC3 - , WFPC2) - , SST (IRAC) - , MMT (Binospec - , BCH) - , Lick (Kast) - , LBT (MODS - , LBC) - , Keck (Deimos) - , SOAR (Goodman). - Software: astropy (Astropy Collaboration et al. 2013).
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
NSFAST-1515559
NSFAST-1821967
NSFAST-182197
NSFAST-1813708
NSFAST-1813466
NSFAST-1908972
Heising-Simons Foundation2020-1864
NSFAST-1813176
Deutsche Forschungsgemeinschaft (DFG)KR4598/2-1
Hungarian Academy of SciencesUNSPECIFIED
Ministry of Technology and Innovation (Hungary)UNKP-20-5
National Research, Development and Innovation Office (Hungary)GINOP-2-3-2-15-2016-00033
Hungarian Scientific Research Fund (OTKA)FK-134432
NASAGO-14668
NASAGO-15166
NASAAR-14295
TABASGO FoundationUNSPECIFIED
Christopher R. Redlich FundUNSPECIFIED
Miller Institute for Basic Research in ScienceUNSPECIFIED
NASAGO-15151
GoogleUNSPECIFIED
NASANAS 5-26555
NASANNX13AC07G
NASA/JPL/CaltechUNSPECIFIED
LBT Corporation PartnersUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:Massive stars; Supergiant stars; Evolved stars; Eruptive variable stars; Luminous blue variable stars
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Massive stars (732); Supergiant stars (1661); Evolved stars (481); Eruptive variable stars (476); Luminous blue variable stars (944)
DOI:10.3847/1538-4357/ac09e1
Record Number:CaltechAUTHORS:20210205-093220958
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210205-093220958
Official Citation:Jennifer E. Andrews et al 2021 ApJ 917 63
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107929
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:05 Feb 2021 23:03
Last Modified:17 Sep 2021 22:18

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