THE YOUNG AND BRIGHT TYPE IA SUPERNOVA ASASSN-14lp: DISCOVERY, EARLY-TIME OBSERVATIONS, FIRST-LIGHT TIME, DISTANCE TO NGC 4666, AND PROGENITOR CONSTRAINTS

Abstract

On 2014 December 9.61, the All-sky Automated Survey for SuperNovae (ASAS-SN or “Assassin”) discovered ASASSN-14lp just ∼2 days after first light using a global array of 14 cm diameter telescopes. ASASSN-14lp went on to become a bright supernova ( V = 11.94 mag), second only to SN 2014J for the year. We present prediscovery photometry (with a detection less than a day after first light) and ultraviolet through near-infrared photometric and spectroscopic data covering the rise and fall of ASASSN-14lp for more than 100 days. We find that ASASSN-14lp had a broad light curve ( ), a B -band maximum at 2457015.82 ± 0.03, a rise time of days, and moderate host-galaxy extinction ( ). Using ASASSN-14lp, we derive a distance modulus for NGC 4666 of , corresponding to a distance of 14.7 ± 1.5 Mpc. However, adding ASASSN-14lp to the calibrating sample of Type Ia supernovae still requires an independent distance to the host galaxy. Finally, using our early-time photometric and spectroscopic observations, we rule out red giant secondaries and, assuming a favorable viewing angle and explosion time, any nondegenerate companion larger than 0.34 .