We present photometry and spectroscopy of SN 2013fs and SN 2013fr in the first ∼ 100 days post-explosion. Both objects showed transient, relatively narrow Hα emission lines characteristic of SNe IIn, but later resembled normal SNe II-P or SNe II-L, indicative of fleeting interaction with circumstellar material (CSM). SN 2013fs was discovered within 8 hr of explosion; one of the earliest SNe discovered thus far. Its light curve exhibits a plateau, with spectra revealing strong CSM interaction at early times. It is a less luminous version of the transitional SN IIn PTF11iqb, further demonstrating a continuum of CSM interaction intensity between SNe II-P and SNe IIn. It requires dense CSM within 6.5 × 1014 cm of the progenitor, from a phase of advanced pre-SN mass loss beginning shortly before explosion. Spectropolarimetry of SN 2013fs shows little continuum polarization (∼ 0.5%, consistent with zero), but noticeable line polarization during the plateau phase. SN 2013fr morphed from a SN IIn at early times to a SN II-L. After the first epoch its narrow lines probably arose from host-galaxy emission, but the bright, narrow Hα emission at early times may be intrinsic to the SN. As for SN 2013fs, this would point to a short-lived phase of strong CSM interaction if proven to be intrinsic, suggesting a continuum between SNe IIn and SNe II-L. It is a low-velocity SN II-L like SN 2009kr, but more luminous. SN 2013fr also developed an infrared excess at later times, due to warm CSM dust that require a more sustained phase of strong pre-SN mass loss.
|Original language||English (US)|
|State||Published - Jan 4 2018|
- Stars: circumstellar matter
- Stars: mass-loss
- Supernovae: general
- Supernovae: individual (SN 2013fs, SN 2013fr)
ASJC Scopus subject areas