Investigating the observational properties of Type Ib supernova SN 2017iro

Abstract

We report results of optical imaging and low-resolution spectroscopic monitoring of supernova (SN) 2017iro that occurred in the nearby (∼ 31 Mpc) galaxy NGC 5480. The He I 5876 Å feature present in the earliest spectrum (-7 d) classified it as a Type Ib SN. The follow-up observations span from -7 to + 266 d with respect to the B-band maximum. With a peak absolute magnitude in V -band, (M V ) = −17.76 ± 0.15 mag and bolometric luminosity (log 10 L) = 42.39 ± 0.09 erg s −1 , SN 2017iro is a moderately luminous Type Ib SN. The overall light curve evolution of SN 2017iro is similar to SN 2012au and SN 2009jf during the early (up to ∼100 d) and late phases (>150 d), respectively. The line velocities of both Fe II 5169 Å and He I 5876 Å are ∼ 9000 km s −1 near the peak. The analysis of the nebular phase spectrum (∼ +209 d) indicates an oxygen mass of ∼ 0.35 M . The smaller [O I]/[Ca II] flux ratio of ∼ 1 favours a progenitor with a zero-age main-sequence mass in the range ∼ 13-15 M , most likely in a binary system, similar to the case of iPTF13bvn. The explosion parameters are estimated by applying different analytical models to the quasi-bolometric light curve of SN 2017iro. 56 Ni mass synthesized in the explosion has a range of ∼ 0.05 -0.10 M , the ejecta mass ∼1.4 -4.3 M and the kinetic energy ∼ 0.8 -1.9 × 10 51 erg.