The Young and Bright Type IA Supernova ASASSN-141p: Discovery, Early-Time Observations, First-Light Time, Distance to NGC 4666, and Progenitor Constraints
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 (Dm B 15 ( ) = 0.80 0.05), a B-band maximum at 2457015.82 ± 0.03, a rise time of - + 16.94 0.10 0.11 days, and moderate host-galaxy extinction (E ( ) B V - = host 0.33 0.06). Using ASASSN-14lp, we derive a distance modulus for NGC 4666 of m = 30.8 0.2, 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 R.
The Astrophysical Journal, 826:144 (12pp), 2016 August 1