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Massive star mergers and the recent transient in NGC 4490: a more massive cousin of V838 Mon and V1309 Sco

Smith, Nathan and Andrews, Jennifer E. and Van Dyk, Schuyler D. and Mauerhan, Jon C. and Kasliwal, Mansi M. and Bond, Howard E. and Filippenko, Alexei V. and Clubb, Kelsey I. and Graham, Melissa L. and Perley, Daniel A. and Jencson, Jacob and Bally, John and Ubeda, Leonardo and Sabbi, Elena (2016) Massive star mergers and the recent transient in NGC 4490: a more massive cousin of V838 Mon and V1309 Sco. Monthly Notices of the Royal Astronomical Society, 458 (1). pp. 950-962. ISSN 0035-8711.

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The Galactic transient V1309 Sco was the result of a merger in a low-mass star system, while V838 Mon was thought to be a similar merger event from a more massive B-type progenitor. In this paper, we study a recent optical and infrared (IR) transient discovered in the nearby galaxy NGC 4490 named NGC 4490-OT2011 (NGC 4490-OT hereafter), which appeared similar to these merger events (unobscured progenitor, irregular multi-peaked light curve, increasingly red colour, similar optical spectrum, IR excess at late times), but which had a higher peak luminosity and longer duration in outburst. NGC 4490-OT has less in common with the class of SN 2008S-like transients. A progenitor detected in pre-eruption Hubble Space Telescope (HST) images, combined with upper limits in the IR, requires a luminous and blue progenitor that has faded in late-time HST images. The same source was detected by Spitzer and ground-based data as a luminous IR (2–5 μm) transient, indicating a transition to a self-obscured state qualitatively similar to the evolution seen in other stellar mergers and in luminous blue variables. The post-outburst dust-obscured source is too luminous and too warm at late times to be explained with an IR echo, suggesting that the object survived the event. The luminosity of the enshrouded IR source is similar to that of the progenitor. Compared to proposed merger events, the more massive progenitor of NGC 4490-OT seems to extend a correlation between stellar mass and peak luminosity, and may suggest that both of these correlate with duration. We show that spectra of NGC 4490-OT and V838 Mon also resemble light-echo spectra of η Car, prompting us to speculate that η Car may be an extreme extension of this phenomenon.

Item Type:Article
Related URLs:
URLURL TypeDescription
Andrews, Jennifer E.0000-0003-0123-0062
Van Dyk, Schuyler D.0000-0001-9038-9950
Kasliwal, Mansi M.0000-0002-5619-4938
Bond, Howard E.0000-0003-1377-7145
Filippenko, Alexei V.0000-0003-3460-0103
Graham, Melissa L.0000-0002-9154-3136
Perley, Daniel A.0000-0001-8472-1996
Jencson, Jacob0000-0001-5754-4007
Bally, John0000-0001-8135-6612
Sabbi, Elena0000-0003-2954-7643
Additional Information:© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 January 25. Received 2016 January 7; in original form 2015 September 16. Some of the data reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. We thank the staffs at Lick and MMT Observatories for their assistance with the observations. We also appreciate the help of Jeff Silverman for some of the Lick observations. Data from Steward Observatory facilities were obtained as part of the observing programme AZTEC: Arizona Transient Exploration and Characterization. Lindsey Kabot assisted with early stages of the MMT spectral data reduction. The work presented here is based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These are based in part on observations associated with programme #13364 (Legacy ExtraGalactic UV Survey, LEGUS). This paper has made use of the higher level data products provided by the LEGUS team. NS and JEA received partial support from National Science Foundation (NSF) grants AST-1210599 and AST-1312221. MMK acknowledges support from the Carnegie-Princeton fellowship. Funding for this effort was provided in part by the Spitzer SPIRITS Cycles 10–12 exploration science programme. The supernova research of AVF's group at U.C. Berkeley presented here is supported by Gary & Cynthia Bengier, the Christopher R. Redlich Fund, the TABASGO Foundation, and NSF grant AST-1211916. KAIT and its ongoing operation were made possible by donations from Sun Microsystems, Inc., the Hewlett-Packard Company, AutoScope Corporation, Lick Observatory, the NSF, the University of California, the Sylvia & Jim Katzman Foundation, and the TABASGO Foundation. Research at Lick Observatory is partially supported by a generous gift from Google. JJ is supported by an NSF Graduate Research Fellowship under Grant No. DGE-1144469.
Group:Infrared Processing and Analysis Center (IPAC), Palomar Transient Factory
Funding AgencyGrant Number
Carnegie-Princeton FellowshipUNSPECIFIED
Gary and Cynthia BengierUNSPECIFIED
Christopher R. Redlich FundUNSPECIFIED
Sun Microsystems, Inc.UNSPECIFIED
Hewlett-Packard CompanyUNSPECIFIED
AutoScope CorporationUNSPECIFIED
Lick ObservatoryUNSPECIFIED
University of CaliforniaUNSPECIFIED
Sylvia and Jim Katzman FoundationUNSPECIFIED
NSF Graduate Research FellowshipDGE-1144469
Subject Keywords:binaries: general circumstellar matter stars: evolution stars: massive stars: winds, outflows
Issue or Number:1
Record Number:CaltechAUTHORS:20160603-083351085
Persistent URL:
Official Citation:Nathan Smith, Jennifer E. Andrews, Schuyler D. Van Dyk, Jon C. Mauerhan, Mansi M. Kasliwal, Howard E. Bond, Alexei V. Filippenko, Kelsey I. Clubb, Melissa L. Graham, Daniel A. Perley, Jacob Jencson, John Bally, Leonardo Ubeda, and Elena Sabbi Massive star mergers and the recent transient in NGC 4490: a more massive cousin of V838 Mon and V1309 Sco MNRAS (May 01, 2016) Vol. 458 950-962 doi:10.1093/mnras/stw219 first published online February 9, 2016
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67638
Deposited By: Ruth Sustaita
Deposited On:03 Jun 2016 16:25
Last Modified:09 Mar 2020 13:19

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