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

Weikang Zheng, Alexei V. Filippenko, Jon Mauerhan, Melissa L. Graham, Heechan Yuk, Griffin Hosseinzadeh, Jeffrey M. Silverman, Liming Rui, Ron Arbour, Ryan J. Foley, Bela Abolfathi, Louis E. Abramson, Iair Arcavi, Aaron J. Barth, Vardha N. Bennert, Andrew P. Brandel, Michael C. Cooper, Maren Cosens, Sean P. Fillingham, Benjamin J. FultonGoni Halevi, D. Andrew Howell, Tiffany Hsyu, Patrick L. Kelly, Sahana Kumar, Linyi Li, Wenxiong Li, Matthew A. Malkan, Christina Manzano-King, Curtis McCully, Peter E. Nugent, Yen Chen Pan, Liuyi Pei, Bryan Scott, Remington Oliver Sexton, Isaac Shivvers, Benjamin Stahl, Tommaso Treu, Stefano Valenti, H. Alexander Vogler, Jonelle L. Walsh, Xiaofeng Wang

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10 Scopus citations

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 kms-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 (MB ≈ -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.

Original languageEnglish (US)
Article number64
JournalAstrophysical Journal
Volume841
Issue number1
DOIs
StatePublished - May 20 2017
Externally publishedYes

Bibliographical note

Funding Information:
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.

Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.

Keywords

  • supernovae: general
  • supernovae: individual (SN 2016coj)

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