SN 2016B a.k.a. ASASSN-16ab: a transitional Type II supernova
Pandey, S. B.; Benetti, S.; Kumar, Brajesh; Tomasella, L.; Anupama, G. C.; Singh, Avinash; Terreran, G.; Kumar, Brijesh; Singh, Mridweeka; Dastidar, Raya; Sahu, D. K.; Pastorello, A.; Misra, Kuntal; Gangopadhyay, Anjasha; Sanwal, Pankaj
India, United States, Italy
Abstract
We present photometry, polarimetry, and spectroscopy of the Type II supernova ASASSN-16ab/SN 2016B in PGC 037392. The photometric and spectroscopic follow-up commenced about 2 weeks after shock breakout and continued until nearly 6 months. The light curve of SN 2016B exhibits intermediate properties between those of Type IIP and IIL. The early decline is steep (1.68 ± 0.10 mag 100 d-1), followed by a shallower plateau phase (0.47 ± 0.24 mag 100 d-1). The optically thick phase lasts for 118 d, similar to Type IIP. The 56Ni mass estimated from the radioactive tail of the bolometric light curve is 0.082 ± 0.019 M⊙. High-velocity component contributing to the absorption trough of H α and H β in the photospheric spectra are identified from the spectral modelling from about 57-97 d after the outburst, suggesting a possible SN ejecta and circumstellar material interaction. Such high-velocity features are common in the spectra of Type IIL supernovae. By modelling the true bolometric light curve of SN 2016B, we estimated a total ejected mass of ∼15 M⊙, kinetic energy of ∼1.4 foe, and an initial radius of ∼400 R⊙.