1. SN 2021foa: Deriving a continuity between SN IIn and SN Ibn
- Author
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Gangopadhyay, Anjasha, Dukiya, Naveen, Moriya, Takashi J, Tanaka, Masaomi, Maeda, Keiichi, Howell, D. Andrew, Singh, Mridweeka, Singh, Avinash, Sollerman, Jesper, Kawabata, Koji S, Brennan, Sean J, Pellegrino, Craig, Dastidar, Raya, Misra, Kuntal, Kawabata, Tatsuya Nakaoka Miho, Schulze, Steve, Chandra, Poonam, Taguchi, Kenta, Sahu, Devendra K, McCully, Curtis, Bostroem, K. Azalee, Gonzalez, Estefania Padilla, Newsome, Megan, Hiramatsu, Daichi, Takei, Yuki, and Yamanaka, Masayuki
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present the long-term photometric and spectroscopic monitoring campaign of a transitioning SN~IIn/Ibn from $-$10.8 d to 150.7 d post $V$-band maximum. SN~2021foa shows prominent He i lines comparable in strength to the H$\alpha$ line around peak luminosity, placing SN~2021foa between the SN~IIn and SN~Ibn populations. The spectral comparison with SNe~IIn and SNe~Ibn shows that it resembles the SN~IIn population at pre-maximum, becomes intermediate between SNe~IIn/Ibn around maximum light, and similar to SN~1996al at late times. The photometric evolution shows a precursor at $-$50 d and a light curve shoulder around 17 d, which matches well with the light curve of the interacting IIns like SN~2016jbu. The peak luminosity and color evolution of SN 2021foa are consistent with most SNe~IIn and SNe~Ibn. SN~2021foa shows the unique case of a SN~IIn where the P-Cygni features in H$\alpha$ appear at later stages, either due to complex geometry of the CSM or an interaction of the ejecta with a CSM shell/disk (similar to SNe~2009ip and 2015bh). Temporal evolution of the H$\alpha$ profile favours a disk-like CSM geometry (CSM having both H and He) with a narrow (500 -- 1200 km s$^{-1}$) component, intermediate width (3000 -- 8000 km s$^{-1}$) and broad component in absorption. Hydrodynamical lightcurve modelling can well-reproduce the lightcurve by a two-component CSM structure with different densities ($\rho$ $\propto$ r$^{-2}$ -- $\rho$ $\propto$ r$^{-5}$), mass-loss rates (10$^{-3}$ -- 10$^{-1}$ M$_{\odot}$ yr$^{-1}$) assuming a wind velocity of 1000 km s$^{-1}$ and having a CSM mass of 0.18 M$_{\odot}$. The overall evolution supports the fact that indicates that SN~2021foa most likely originated from a LBV star transitioning to a WR star with the mass-loss rate increasing in the period from 5 to 0.5 years before the explosion or it could be due to a binary interaction., Comment: To be submitted to MNRAS in few days; 20 pages, 16 figures, 4 tables
- Published
- 2024