The highly luminous Type Ibn supernova ASASSN-14ms. Issue 2 (22nd December 2017) - Vallely, P J
Abstract: We present photometric and spectroscopic follow-up observations of the highly luminous Type Ibn supernova ASASSN-14ms, which was discovered on UT 2014-12-26.61 at m V ∼ 16.5. With a peak absolute V -band magnitude brighter than −20.5, a peak bolometric luminosity of 1.7 × 10 44 erg s −1, and a total radiated energy of 2.1 × 10 50 erg, ASASSN-14ms is one of the most luminous Type Ibn supernovae yet discovered. In simple models, the most likely power source for this event is a combination of the radioactive decay of 56 Ni and 56 Co at late times and the interaction of supernova ejecta with the progenitor's circumstellar medium at early times, although we cannot rule out the possibility of a magnetar-powered light curve. The presence of a dense circumstellar medium is indicated by the intermediate-width He i features in the spectra. The faint ( m g ∼ 21.6) host galaxy SDSS J130408.52+521846.4 has an oxygen abundance below 12 + log (O/H) ≲ 8.3, a stellar mass of M * ∼ 2.6 × 10 8 M⊙, and a star formation rate of SFR ∼ 0.02 M⊙ yr −1 .