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

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. In this study, 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 (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.more » Finally, 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.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ;  [1] ; ORCiD logo [3] ; ORCiD logo [4] ;  [5] ;  [6] ;  [7] ;  [8] ; ORCiD logo [9] ; ORCiD logo [3] ; ORCiD logo [8] ; ORCiD logo [10] ;  [8] ; ORCiD logo [8] ;  [10] ;  [8] ; ORCiD logo [11] more »;  [1] ; ORCiD logo [3] ;  [7] ; ORCiD logo [1] ;  [1] ;  [5] ;  [5] ; ORCiD logo [9] ;  [12] ; ORCiD logo [3] ; ORCiD logo [13] ;  [7] ;  [8] ;  [12] ;  [12] ; ORCiD logo [1] ;  [1] ; ORCiD logo [9] ;  [14] ;  [8] ; ORCiD logo [15] ; ORCiD logo [5] « less
  1. Univ. of California, Berkeley, CA (United States)
  2. Univ. of California, Berkeley, CA (United States) ; Univ. of Washington, Seattle, WA (United States)
  3. Las Cumbres Observatory Global Telescope Network, Goleta, CA (United States); Univ. of California, Santa Barbara, CA (United States)
  4. Univ. of Texas, Austin, TX (United States)
  5. Tsinghua University, Beijing (China)
  6. Pennel Observatory, South Wonston (United Kingdom)
  7. Univ. of California, Santa Cruz, CA (United States)
  8. Univ. of California, Irvine, CA (United States)
  9. Univ. of California, Los Angeles, CA (United States)
  10. California Polytechnic State University, San Luis Obispo, CA (United States)
  11. Univ. of Hawaii, Honolulu, HI (United States)
  12. Univ. of California, Riverside, CA (United States)
  13. Univ. of California, Berkeley, CA (United States) ; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  14. Univ. of California, Davis, CA (United States)
  15. Texas A & M Univ., College Station, TX (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 841; Journal Issue: 1; Related Information: © 2017. The American Astronomical Society. All rights reserved.; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; supernovae: general; supernovae - individual
OSTI Identifier:
1456972