Massive stars exploding in a He-rich circumstellar medium. V. Observations of the slow-evolving SN Ibn OGLE-2012-SN-006
Abstract
We present optical observations of the peculiar Type Ibn supernova (SN Ibn) OGLE-2012-SN-006, discovered and monitored by the OGLE-IV survey, and spectroscopically followed by PESSTO at late phases. Stringent pre-discovery limits constrain the explosion epoch with fair precision to JD = 2456203.8 +- 4.0. The rise time to the I-band light curve maximum is about two weeks. The object reaches the peak absolute magnitude M(I) = -19.65 +- 0.19 on JD = 2456218.1 +- 1.8. After maximum, the light curve declines for about 25 days with a rate of 4 mag per 100d. The symmetric I-band peak resembles that of canonical Type Ib/c supernovae (SNe), whereas SNe Ibn usually exhibit asymmetric and narrower early-time light curves. Since 25 days past maximum, the light curve flattens with a decline rate slower than that of the 56Co to 56Fe decay, although at very late phases it steepens to approach that rate. An early-time spectrum is dominated by a blue continuum, with only a marginal evidence for the presence of He I lines marking this SN Type. This spectrum shows broad absorptions bluewards than 5000A, likely O II lines, which are similar to spectral features observed in super-luminous SNe at early epochs. The object has been spectroscopically monitored by PESSTO from 90 to 180 days after peak, and these spectra show the typical features observed in a number of SN 2006jc-like events, including a blue spectral energy distribution and prominent and narrow (v(FWHM) ~ 1900 km/s) He I emission lines. This suggests that the ejecta are interacting with He-rich circumstellar material. The detection of broad (10000 km/s) O I and Ca II features likely produced in the SN ejecta (including the [O I] 6300A,6364A doublet in the latest spectra) lends support to the interpretation of OGLE-2012-SN-006 as a core-collapse event.
Keywords
Cite
@article{arxiv.1502.04945,
title = {Massive stars exploding in a He-rich circumstellar medium. V. Observations of the slow-evolving SN Ibn OGLE-2012-SN-006},
author = {A. Pastorello and L. Wyrzykowski and S. Valenti and J. L. Prieto and S. Kozlowski and A. Udalski and N. Elias-Rosa and A. Morales-Garoffolo and J. P. Anderson and S. Benetti and M. Bersten and M. T. Botticella and E. Cappellaro and G. Fasano and M. Fraser and A. Gal-Yam and M. Gillone and M. L. Graham and J. Greiner and S. Hachinger and D. A. Howell and C. Inserra and J. Parrent and A. Rau and S. Schulze and S. J. Smartt and K. W. Smith and M. Turatto and O. Yaron and D. R. Young and M. Kubiak and M. K. Szymanski and G. Pietrzynski and I. Soszynski and K. Ulaczyk and R. Poleski and P. Pietrukowicz and J. Skowron and P. Mroz},
journal= {arXiv preprint arXiv:1502.04945},
year = {2015}
}
Comments
16 pages, 9 figures, 4 tables. Accepted by MNRAS