1. Discovery and Follow-up Observations of the Young Type Ia Supernova 2016coj
- Author
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Zheng, WeiKang, Filippenko, Alexei V, Mauerhan, Jon, Graham, Melissa L, Yuk, Heechan, Hosseinzadeh, Griffin, Silverman, Jeffrey M, Rui, Liming, Arbour, Ron, Foley, Ryan J, Abolfathi, Bela, Abramson, Louis E, Arcavi, Iair, Barth, Aaron J, Bennert, Vardha N, Brandel, Andrew P, Cooper, Michael C, Cosens, Maren, Fillingham, Sean P, Fulton, Benjamin J, Halevi, Goni, Howell, D Andrew, Hsyu, Tiffany, Kelly, Patrick L, Kumar, Sahana, Li, Linyi, Li, Wenxiong, Malkan, Matthew A, Manzano-King, Christina, McCully, Curtis, Nugent, Peter E, Pan, Yen-Chen, Pei, Liuyi, Scott, Bryan, Sexton, Remington Oliver, Shivvers, Isaac, Stahl, Benjamin, Treu, Tommaso, Valenti, Stefano, Vogler, H Alexander, Walsh, Jonelle L, and Wang, Xiaofeng
- Subjects
Astronomical Sciences ,Physical Sciences ,supernovae: general ,supernovae: individual ,astro-ph.SR ,astro-ph.GA ,astro-ph.HE ,Astronomical and Space Sciences ,Atomic ,Molecular ,Nuclear ,Particle and Plasma Physics ,Physical Chemistry (incl. Structural) ,Astronomy & Astrophysics ,Astronomical sciences ,Particle and high energy physics ,Space sciences - 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.
- Published
- 2017