Optical studies of SN 2009jf: A type Ib supernova with an extremely slow decline and aspherical signature

Optical \(UBVRI\) photometry and medium resolution spectroscopy of the type Ib supernova SN 2009jf, during the period \(\sim -15\) to +250days with respect to the \(B\) maximum are reported. The light curves are broad, with an extremely slow decline. The early post-maximum decline rate in the \(V\) band is similar to SN 2008D, however, the late phase decline rate is slower than other studied type Ib supernovae. With an absolute magnitude of \(M_{V} = -17.96\pm0.19\) magnitude at peak, SN 2009jf is a normally bright supernova. The peak bolometric luminosity and the energy deposition rate via \(^{56}\)Ni \(\rightarrow\) \(^{56}\)Co chain indicate that \(\sim {0.17}^{+0.03}_{-0.03}\) M\(_{\odot}\) of \(^{56}\)Ni was ejected during the explosion. He\,I 5876 \AA\ line is clearly identified in the first spectrum of day \(\sim -15\), at a velocity of \(\sim 16000\) km sec\(^{-1}\). The [O\,I] 6300-6364 \AA\ line seen in the nebular spectrum has a multi-peaked and asymmetric emission profile, with the blue peak being stronger. The estimated flux in this line implies \(\ga 1.34\) M\(_\odot\) oxygen was ejected. The slow evolution of the light curves of SN 2009jf indicates the presence of a massive ejecta. The high expansion velocity in the early phase and broader emission lines during the nebular phase suggest it to be an explosion with a large kinetic energy. A simple qualitative estimate leads to the ejecta mass of M\(_{\rm ej} = 4-9\) M\(_\odot\), and kinetic energy E\(_{\rm K} = 3-8 \times 10^{51}\) erg. The ejected mass estimate is indicative of an initial main-sequence mass of \(\ga 20- 25\) M\(_\odot\).