Preliminary Results from the Caltech Core‐Collapse Project (CCCP)

摘要

We present preliminary results from the Caltech Core‐Collapse Project (CCCP), a large observational program focused on the study of core‐collapse SNe. Uniform, high‐quality NIR and optical photometry and multi‐epoch optical spectroscopy have been obtained using the 200″ Hale and robotic 60″ telescopes at Palomar, for a sample of 50 nearby core‐collapse SNe. The combination of both well‐sampled optical light curves and multi‐epoch spectroscopy will enable spectroscopically and photometrically based subtype definitions to be disentangled from each other. Multi‐epoch spectroscopy is crucial to identify transition events that evolve among subtypes with time. The CCCP SN sample includes every core‐collapse SN discovered between July 2004 and September 2005 that was visible from Palomar, found shortly (< 30 days) after explosion (based on available pre‐explosion photometry), and closer than ∼ 120 Mpc. This complete sample allows, for the first time, a study of core‐collapse SNe as a population, rather than as individual events. Here, we present the full CCCP SN sample and show exemplary data collected. We analyze available data for the first ∼ 1/3 of the sample and determine the subtypes of 13 SNe II based on both light curve shapes and spectroscopy. We discuss the relative SN II subtype fractions in the context of associating SN subtypes with specific progenitor stars.