Abstract Details

Name: Raya Dastidar
Affiliation: Aryabhatta Research Institute of observational sciencES, Nainital, India
Conference ID: ASI2020_409
Title : SN 2015an: a normal luminosity type II supernova with low expansion velocity at early phases
Authors and Co-Authors : Raya Dastidar, Kuntal Misra, Stefano Valenti, Jamison Burke, Griffin Hosseinzadeh, Anjasha Gangopadhyay, D Andrew Howell, Mridweeka Singh, Iair Arcavi, Brijesh Kumar, Curtis McCully, Pankaj Sanwal, S B Pandey
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : Type II supernovae (SNe) are the hydrogen-rich explosions in massive stars which exhibit diverse properties in the optical domain. To enrich our understanding of the inhomogeneous class of SNe II, detailed studies of these events particularly the deviant objects are important. In this poster, we present the photometry and spectroscopy of SN 2015an, a type II Supernova in IC 2367. The recombination phase of the SN lasts up to 120 d, with a decline rate of 1.24 mag/100d, higher than the typical SNe IIP. The SN exhibits bluer colours than most SNe II, indicating higher ejecta temperatures. The absolute V-band magnitude of SN 2015an at 50 d is −16.83 ± 0.04 mag, pretty typical for SNe II. However, the Ni-56 mass yield, estimated from the tail V-band light curve to be 0.021 ± 0.010 M⊙, is comparatively low. The spectral properties of SN 2015an are atypical, with low H α expansion velocity and presence of high-velocity component of H α at early phases. Moreover, the continuum exhibits excess blue flux up to 50 d, which is interpreted as a progenitor metallicity effect. The high-velocity feature indicates ejecta-circumstellar material interaction at early phases. The semi-analytical modelling of the bolometric light curve yields a total ejected mass of 12 M⊙, a pre-SN radius of 388 R⊙ and explosion energy of 1.8 foe.