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SN 2019ehk: A Double-peaked Ca-rich Transient with Luminous X-Ray Emission and Shock-ionized Spectral Features

Jacobson-Galán, Wynn V. and Margutti, Raffaella and Kilpatrick, Charles D. and Hiramatsu, Daichi and Perets, Hagai and Khatami, David and Foley, Ryan J. and Raymond, John and Yoon, Sung-Chul and Bobrick, Alexey and Zenati, Yossef and Galbany, Lluís and Andrews, Jennifer and Brown, Peter J. and Cartier, Régis and Coppejans, Deanne L. and Dimitriadis, Georgios and Dobson, Matthew and Hajela, Aprajita and Howell, D. Andrew and Kuncarayakti, Hanindyo and Milisavljevic, Danny and Rahman, Mohammed and Rojas-Bravo, César and Sand, David J. and Shepherd, Joel and Smartt, Stephen J. and Stacey, Holland and Stroh, Michael and Swift, Jonathan J. and Terreran, Giacomo and Vinko, Jozsef and Wang, Xiaofeng and Anderson, Joseph P. and Baron, Edward A. and Berger, Edo and Blanchard, Peter K. and Burke, Jamison and Coulter, David A. and DeMarchi, Lindsay and DerKacy, James M. and Fremling, Christoffer and Gomez, Sebastian and Gromadzki, Mariusz and Hosseinzadeh, Griffin and Kasen, Daniel and Kriskovics, Levente and McCully, Curtis and Müller-Bravo, Tomás E. and Nicholl, Matt and Ordasi, András and Pellegrino, Craig and Piro, Anthony L. and Pál, András and Ren, Juanjuan and Rest, Armin and Rich, R. Michael and Sai, Hanna and Sárneczky, Krisztián and Shen, Ken J. and Short, Philip and Siebert, Matthew R. and Stauffer, Candice and Szakáts, Róbert and Zhang, Xinhan and Zhang, Jujia and Zhang, Kaicheng (2020) SN 2019ehk: A Double-peaked Ca-rich Transient with Luminous X-Ray Emission and Shock-ionized Spectral Features. Astrophysical Journal, 898 (2). Art. No. 166. ISSN 1538-4357.

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We present panchromatic observations and modeling of the Calcium-rich supernova (SN) 2019ehk in the star-forming galaxy M100 (d ≈ 16.2 Mpc) starting 10 hr after explosion and continuing for ~300 days. SN 2019ehk shows a double-peaked optical light curve peaking at t = 3 and 15 days. The first peak is coincident with luminous, rapidly decaying Swift-XRT–discovered X-ray emission (L_x ≈ 10⁴¹ erg s⁻¹ at 3 days; L_x ∝ t⁻³), and a Shane/Kast spectral detection of narrow Hα and He II emission lines (v ≈ 500 km s⁻¹) originating from pre-existent circumstellar material (CSM). We attribute this phenomenology to radiation from shock interaction with extended, dense material surrounding the progenitor star at r < 10¹⁵ cm and the resulting cooling emission. We calculate a total CSM mass of ~7 × 10⁻³ M_⊙ (M_(He)/M_H ≈6) with particle density n ≈ 10⁹ cm⁻³. Radio observations indicate a significantly lower density n < 10⁴ cm⁻³ at larger radii r > (0.1–1) × 10¹⁷ cm. The photometric and spectroscopic properties during the second light-curve peak are consistent with those of Ca-rich transients (rise-time of t_r = 13.4 ± 0.210 days and a peak B-band magnitude of M_B = −15.1 ± 0.200 mag). We find that SN 2019ehk synthesized (3.1 ± 0.11) × 10⁻² M_⊙ of ⁵⁶Ni and ejected M_(ej) = (0.72 ± 0.040) M⊙ total with a kinetic energy E_k = (1.8 ± 0.10) × 10⁵⁰ erg. Finally, deep HST pre-explosion imaging at the SN site constrains the parameter space of viable stellar progenitors to massive stars in the lowest mass bin (~10 M_⊙) in binaries that lost most of their He envelope or white dwarfs (WDs). The explosion and environment properties of SN 2019ehk further restrict the potential WD progenitor systems to low-mass hybrid HeCO WD+CO WD binaries.

Item Type:Article
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URLURL TypeDescription Paper
Jacobson-Galán, Wynn V.0000-0003-1103-3409
Margutti, Raffaella0000-0003-4768-7586
Kilpatrick, Charles D.0000-0002-5740-7747
Hiramatsu, Daichi0000-0002-1125-9187
Perets, Hagai0000-0002-5004-199X
Khatami, David0000-0003-4307-0589
Raymond, John0000-0002-7868-1622
Yoon, Sung-Chul0000-0002-5847-8096
Bobrick, Alexey0000-0002-4674-0704
Galbany, Lluís0000-0002-1296-6887
Andrews, Jennifer0000-0003-0123-0062
Brown, Peter J.0000-0001-6272-5507
Coppejans, Deanne L.0000-0001-5126-6237
Dimitriadis, Georgios0000-0001-9494-179X
Hajela, Aprajita0000-0003-2349-101X
Howell, D. Andrew0000-0003-4253-656X
Kuncarayakti, Hanindyo0000-0002-1132-1366
Milisavljevic, Danny0000-0002-0763-3885
Rojas-Bravo, César0000-0002-7559-315X
Sand, David J.0000-0003-4102-380X
Smartt, Stephen J.0000-0002-8229-1731
Stroh, Michael0000-0002-3019-4577
Swift, Jonathan J.0000-0002-9486-818X
Terreran, Giacomo0000-0003-0794-5982
Vinko, Jozsef0000-0001-8764-7832
Wang, Xiaofeng0000-0002-7334-2357
Anderson, Joseph P.0000-0003-0227-3451
Baron, Edward A.0000-0001-5393-1608
Berger, Edo0000-0002-9392-9681
Blanchard, Peter K.0000-0003-0526-2248
Coulter, David A.0000-0003-4263-2228
DeMarchi, Lindsay0000-0003-4587-2366
Fremling, Christoffer0000-0002-4223-103X
Gomez, Sebastian0000-0001-6395-6702
Gromadzki, Mariusz0000-0002-1650-1518
Hosseinzadeh, Griffin0000-0002-0832-2974
McCully, Curtis0000-0001-5807-7893
Nicholl, Matt0000-0002-2555-3192
Pellegrino, Craig0000-0002-7472-1279
Piro, Anthony L.0000-0001-6806-0673
Pál, András0000-0001-5449-2467
Rich, R. Michael0000-0003-0427-8387
Shen, Ken J.0000-0002-9632-6106
Zhang, Jujia0000-0002-8296-2590
Additional Information:© 2020 The American Astronomical Society. Received 2020 May 4; revised 2020 June 16; accepted 2020 June 17; published 2020 August 5. We thank David Matthews, Enrico Ramirez-Ruiz, Brian Metzger, and Nathan Smith for stimulating conversations and constructive comments in regard to this work. W.J.-G. is supported by the National Science Foundation Graduate Research Fellowship Program under grant No. DGE-1842165 and the Data Science Initiative Fellowship from Northwestern University. R.M. is grateful to KITP for hospitality during the completion of this paper. This research was supported in part by the National Science Foundation under grant No. NSF PHY-1748958. R.M. acknowledges support by the National Science Foundation under Award No. AST-1909796. Raffaella Margutti is a CIFAR Azrieli Global Scholar in the Gravity & the Extreme Universe Program, 2019. The Margutti's team at Northwestern is partially funded by the Heising-Simons Foundation under grant # 2018-0911 (PI: Margutti). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. The scientific results reported in this article are based in part on observations made by the Chandra. This research has made use of software provided by the Chandra X-ray Center (CXC) in the application packages CIAO. Partial support for this work was provided by the National Aeronautics and Space Administration through Chandra Award Number DD0-21114X issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060. W. M. Keck Observatory [and/or MMT Observatory] access was supported by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). The UCSC transient team is supported in part by NSF grant AST-1518052, NASA/Swift grant 80NSSC19K1386, the Gordon & Betty Moore Foundation, the Heising-Simons Foundation, and by a fellowship from the David and Lucile Packard Foundation to R.J.F. Research at Lick Observatory is partially supported by a generous gift from Google. A.H. is partially supported by the Future Investigators in NASA Earth and Space Science and Technology (FINESST) Award No. 80NSSC19K1422. H.B.P. acknowledges support from the Kingsely distinguished-visitor program at Caltech, as well as the KITP visitor program. K.J.S. is supported by NASA through the Astrophysics Theory Program (NNX17AG28G). P.J.B. is supported by a NASA Swift Guest Investigator grant 80NSSC19K0316. TMB was funded by the CONICYT PFCHA/DOCTORADOBECAS CHILE/2017-72180113. S.C.Y. is supported by the National Research Foundation of Korea (NRF) grant (NRF-2019R1A2C2010885). M.G. is supported by the Polish NCN MAESTRO grant 2014/14/A/ST9/00121. D.A.H., J.B., D.H., and C.P. are supported by NSF AST-1911225 and NASA grant 80NSSC19K1639. J.D. and E.B. are supported in part by NASA Grant 80NSSC20K0456. S.J.S. acknowledges funding from STFC Grant ST/P000312/1. M.R.S. is supported by the National Science Foundation Graduate Research Fellowship Program under grant No. 1842400. Research by D.J.S. is supported by NSF grants AST-1821967, 1821987, 1813708, 1813466, and 1908972. This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 15645. X. Wang is supported by the National Natural Science Foundation of China (NSFC grants 11325313, 11633002, and 11761141001), and the National Program on Key Research and Development Project (grant No. 2016YFA0400803). We acknowledge the support of the staff of the Xinglong 2.16 m telescope. This work was partially supported by the Open Project Program of the Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences. Funding for the LJT has been provided by Chinese Academy of Sciences and the People's Government of Yunnan Province. The LJT is jointly operated and administrated by Yunnan Observatories and Center for Astronomical Mega-Science, CAS. Based 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). Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. 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 the National Aeronautics and Space Administration. 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. We wish to recognize the destructive history of colonialism endured by native Hawaiians as we strive to hear the voice of those whose sacred land we continue to utilize for scientific gain. This work includes data obtained with the Swope Telescope at Las Campanas Observatory, Chile, as part of the Swope Time Domain Key Project (PI: Piro, Co-Is: Drout, Phillips, Holoien, French, Cowperthwaite, Burns, Madore, Foley, Kilpatrick, Rojas-Bravo, Dimitriadis, Hsiao). We wish to thank Swope Telescope observers Jorge Anais Vilchez, Abdo Campillay, Nahir Munoz Elgueta, and Natalie Ulloa for collecting data presented in this paper. This research has made use of the XRT Data Analysis Software (XRTDAS) developed under the responsibility of the ASI Science Data Center (ASDC), Italy. The SN group at Konkoly Observatory is supported by the project "Transient Astrophysical Objects" GINOP 2.3.2-15-2016-00033 of the National Research, Development and Innovation Office (NKFIH), Hungary, funded by the European Union. Based on observations collected at the European Southern Observatory under ESO program 1103.D-0328. This work has made use of data from the Asteroid Terrestrial-impact Last Alert System (ATLAS) project. ATLAS is primarily funded to search for near earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen's University Belfast, and the Space Telescope Science Institute. Facilities: Hubble Space Telescope - , Spitzer Space Telescope - , Chandra X-ray Observatory - , Neil Gehrels Swift Observatory - , VLA - , Las Campanas Observatory - , Zwicky Transient Facility - , Konkoly Observatory - , ATLAS - , Thacher Observatory - , Swope:1 m - , Multi Unit Spectroscopic Explorer (MUSE) - , Shane (Kast) - , Xinglong Observatory (BFOSC) - , MMT (Binospec) - , Bok (B&C) - , Faulkes North (FLOYDS) - , NTT (EFOSC2) - , LJT (YFOSC) - , SOAR (Goodman - , Triple-Spec) - , Keck I (LRIS). - Software: emcee (Foreman-Mackey et al. 2013), SNID (Blondin & Tonry 2007), Superfit (Howell et al. 2005), IRAF, AstroDrizzle (Gonzaga 2012), photpipe (Rest et al. 2005), DoPhot (Schechter et al. 1993), HOTPANTS (Becker 2015), Sedona (Kasen et al. 2006), SYN++/SYNAPPS (Thomas et al. 2011), Castro (Almgren et al. 2010), BPASS (Eldridge et al. 2017), MESA (Choi et al. 2016), sextractor (Bertin & Arnouts 1996), HEAsoft (v6.22; HEASARC 2014).
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1842165
Northwestern UniversityUNSPECIFIED
Canadian Institute for Advanced Research (CIFAR)UNSPECIFIED
Heising-Simons Foundation2018-0911
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)UNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
NASA Earth and Space Science Fellowship80NSSC19K1422
Kavli Institute for Theoretical PhysicsUNSPECIFIED
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)2017-72180113
National Research Foundation of KoreaNRF-2019R1A2C2010885
National Science Centre (Poland)2014/14/A/ST9/00121
Science and Technology Facilities Council (STFC)ST/P000312/1
NSF Graduate Research FellowshipDGE-1842400
NASANAS 5-26555
National Natural Science Foundation of China11325313
National Natural Science Foundation of China11633002
National Natural Science Foundation of China11761141001
National Program on Key Research and Development Project2016YFA0400803
National Astronomical Observatories, Chinese Academy of Sciences (NAOC)UNSPECIFIED
People's Government of Yunnan ProvinceUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
National Research, Development and Innovation FundGINOP 2.3.2-15-2016-00033
Subject Keywords:Supernovae ; White dwarf stars ; Core-collapse supernovae ; X-ray telescopes ; Stellar mass loss ; Stellar phenomena ; Transient sources
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Supernovae (1668); White dwarf stars (1799); Core-collapse supernovae (304); X-ray telescopes (1825); Stellar mass loss (1613); Stellar phenomena (1619); Transient sources (1851)
Record Number:CaltechAUTHORS:20200805-115722041
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Official Citation:Wynn V. Jacobson-Galán et al 2020 ApJ 898 166
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104757
Deposited By: Tony Diaz
Deposited On:05 Aug 2020 19:26
Last Modified:05 Aug 2020 19:26

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