Discovery and Follow-up Observations of the Young Type Ia Supernova 2016coj

Creators: Zheng, WeiKang; Fulton, Benjamin J.

Abstract

The Type Ia supernova (SN Ia) 2016coj in NGC 4125 (redshift z = 0.00452 ± 0.00006) was discovered by the Lick Observatory Supernova Search 4.9 days after the fitted first-light time (FFLT; 11.1 days before B-band maximum). Our first detection (prediscovery) is merely 0.6 ± 0.5 days after the FFLT, making SN 2016coj one of the earliest known detections of an SN Ia. A spectrum was taken only 3.7 hr after discovery (5.0 days after the FFLT) and classified as a normal SN Ia. We performed high-quality photometry, low- and high-resolution spectroscopy, and spectropolarimetry, finding that SN 2016coj is a spectroscopically normal SN Ia, but the velocity of Si II λ6355 around peak brightness (~12,600 km s^(-1)) is a bit higher than that of typical normal SNe. The Si II λ6355 velocity evolution can be well fit by a broken-power-law function for up to a month after the FFLT. SN 2016coj has a normal peak luminosity (M_B ≈ -18.9 ± 0.2 mag), and it reaches a B-band maximum ~16.0 days after the FFLT. We estimate there to be low host-galaxy extinction based on the absence of Na I D absorption lines in our low- and high-resolution spectra. The spectropolarimetric data exhibit weak polarization in the continuum, but the Si II line polarization is quite strong (~0.9% ± 0.1%) at peak brightness.

Additional Information

© 2017 The American Astronomical Society. Received 2016 November 28; revised 2017 April 17; accepted 2017 April 17; published 2017 May 24. A.V.F.'s group at U.C. Berkeley is grateful for financial assistance from National Science Foundation (NSF) grant AST-1211916, Gary and Cynthia Bengier, the Richard and Rhoda Goldman Fund, the Christopher R. Redlich Fund, and the TABASGO Foundation. J.M.S. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1302771. UC Irvine observing runs were supported in part by NSF grant AST-1412693. Some of the data presented herein were obtained using the UC Berkeley and UC Irvine Remote Observing Facilities, made possible by generous gifts from John and Astrid Preston (UCB) and John and Ruth Ann Evans (UCI). V.N.B. and M.C. gratefully acknowledge assistance from an NSF Research at Undergraduate Institutions (RUI) grant AST-1312296. The UCSC group is supported in part by NSF grant AST-1518052, and by fellowships from the Alfred P. Sloan Foundation and the David and Lucile Packard Foundation to R.J.F. Observations by the UCLA group are supported by NSF grant AST-1412315 to T.T. The National Science Foundation of China financially supports X.W. (NSFC grants 11178003, 11325313, and 11633002). This work was partially supported by the Open Project Program of the Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences. G.H., C.M., and D.A.H. are supported by NSF grant AST-1313484. Support for I.A. was provided by NASA through the Einstein Fellowship Program, grant PF6-170148. We thank the staffs of the various observatories at which data were obtained. Some of the data presented herein were obtained at the W. M. Keck Observatory, which was made possible by the generous financial support of the W. M. Keck Foundation. Based in part on observations obtained at Kitt Peak National Observatory, National Optical Astronomy Observatory (NOAO Prop. ID 2015B-0313; PI Foley), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under cooperative agreement with the NSF. The authors are honored to be permitted to conduct astronomical research on Iolkam Du'ag (Kitt Peak), a mountain with particular significance to the Tohono O'odham. This work makes use of observations from the LCOGT network. We thank Lauren Weiss and Bradford Holden for obtaining APF data at Lick Observatory. 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 and Jim Katzman Foundation, and the TABASGO Foundation. Research at the Lick Observatory is partially supported by a generous gift from Google.

Attached Files

Published - Zheng_2017_ApJ_841_64.pdf

Submitted - 1611.09438.pdf

Files

1611.09438.pdf

Files (3.1 MB)

Name	Size	Download all
1611.09438.pdf md5:cbeb56e74752443d69d48065e48b5570	1.2 MB	Preview Download
Zheng_2017_ApJ_841_64.pdf md5:66e72d8bf2d15817e063fadb168d0a10	2.0 MB	Preview Download

Additional details

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes