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PTF14jg: The Remarkable Outburst and Post-burst Evolution of a Previously Anonymous Galactic Star

Hillenbrand, Lynne A. and Miller, Adam A. and Carpenter, John M. and Kasliwal, Mansi M. and Isaacson, Howard and Tang, Sumin and Joshi, Vishal and Banerjee, D. P. K. and Cutri, Roc M. (2019) PTF14jg: The Remarkable Outburst and Post-burst Evolution of a Previously Anonymous Galactic Star. Astrophysical Journal, 874 (1). Art. No. 82. ISSN 1538-4357. http://resolver.caltech.edu/CaltechAUTHORS:20190326-084628949

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Abstract

We report the outbursting source PTF 14jg, which, prior to the onset of its late 2013 eruption, was a faint, unstudied, and virtually uncataloged star. The salient features of the PTF 14jg outburst are (i) projected location near the W4 H II region and radial velocity consistent with physical association; (ii) a light curve that underwent an ~6–7 mag optical (R-band) through mid-infrared (L-band) brightening on a timescale of a few months, peaked and then faded by ~3 mag, but plateaued still >3.5 mag above quiescence by ~8 months post-peak, lasting to at least 4 yr after eruption; (iii) strong outflow signatures with velocities reaching −530 km s^(-1); (iv) a low-gravity and broad (~100–150 km s^(-1) FWHM) optical absorption-line spectrum that systematically changes its spectral type with wavelength; (v) lithium; and (vi) ultraviolet and infrared excess. We tentatively identify the outburst as exhibiting characteristics of a young star FU Ori event. However, the burst would be unusually hot, with an absorption spectrum exhibiting high-excitation (~11,000–15,000 K) lines in the optical and no evidence of CO in the near-infrared, in addition to exhibiting an unusual light curve. We thus also consider alternative scenarios—including various forms of novae, nuclear-burning instabilities, massive star events, and mergers—finding them all inferior to the atypically hot FU Ori star classification. The source eventually may be interpreted as a new category of young star outburst with a larger amplitude and shorter rise time than most FU Ori–like events.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/ab06c8DOIArticle
https://arxiv.org/abs/1901.10693arXivDiscussion Paper
ORCID:
AuthorORCID
Carpenter, John M.0000-0003-2251-0602
Kasliwal, Mansi M.0000-0002-5619-4938
Isaacson, Howard0000-0002-0531-1073
Tang, Sumin0000-0002-6225-8918
Cutri, Roc M.0000-0002-0077-2305
Additional Information:© 2019 The American Astronomical Society. Received 2018 July 27; revised 2019 January 27; accepted 2019 January 28; published 2019 March 26. We have made extensive use of SIMBAD and ADS online resources in sleuthing for possible analogs of PTF 14jg. We also spent a considerable amount of quality time with the NIST atomic database in attemping line identification in the HIRES data, and we consulted the MILES population synthesis spectral database when searching for spectral templates. We are grateful to Cathie Clarke and Giuseppe Lodato for locating electronic copies of photometric data on the "classical" FU Ori outbursts that were published in their 2005 paper and to Ariel Langer, who contributed to our analysis of these light curves. We thank Mark Heyer for locating CO channel maps from his 1998 paper. We benefited from allocations by Tom Soifer as director of the Spitzer Space Telescope and Lee Mundy as director of CARMA of small amounts of DDT to obtain the observations reported here. We thank the spectroscopic observers listed in Table 6 who are not otherwise acknowledged with authorship, especially Yi Cao, Sumin Tang, Jacob Jencson, and Anna Ho. D.P.K.B. thanks N. M. Ashok and V. Venkataraman for help with some of the Mount Abu observations. The research at PRL is supported by the Department of Space, Government of India. We thank the staff members at the various observational facilities used and the numerous instrument builders. The Intermediate Palomar Transient Factory project is a scientific collaboration among the California Institute of Technology, Los Alamos National Laboratory, the University of Wisconsin–Milwaukee, the Oskar Klein Center, the Weizmann Institute of Science, the TANGO Program of the University System of Taiwan, and the Kavli Institute for the Physics and Mathematics of the Universe. Finally, L.A.H. is grateful for the tolerance of the many young star and nova pundits on whom various versions of this story have been tried out over the past several years. And we thank the referee for comments that provided a valuable opportunity for us to reexamine our presentation. Facilities: PO:1.2m:PTF - , PO:1.5m:GRBcam - , MIRO:1.2m - , Hale:DBSP - , Hale:TSPEC - , Keck:I:HIRES - , Keck:I:LRIS - , Keck:I:DEIMOS - , Keck:I:MOSFIRE - , APO:DIS - , APO:TSPEC - , 2MASS - , Spitzer, WISE(NEOWISE) - , Swift:UVOT - , Swift:XRT - , CARMA - Combined Array for Research in Millimeter-Wave Astronomy, IRSA. -
Group:Infrared Processing and Analysis Center (IPAC), Palomar Transient Factory
Funders:
Funding AgencyGrant Number
Department of Space (India)UNSPECIFIED
Subject Keywords:circumstellar matter – infrared: stars – stars: activity – stars: pre-main sequence – stars: variables: general – stars: winds, outflows
Record Number:CaltechAUTHORS:20190326-084628949
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20190326-084628949
Official Citation:Lynne A. Hillenbrand et al 2019 ApJ 874 82
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94138
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:26 Mar 2019 16:22
Last Modified:21 May 2019 19:34

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