Persistent Cii Absorption In the Normal TYPE Ia Supernova 2002fk∗

Abstract

We present well-sampled UBVRIJHK photometry of SN 2002fk starting 12 days before maximum light through 122 days after peak brightness, along with a series of 15 optical spectra from −4 to +95 days since maximum. Our observations show the presence of C ii lines in the early-time spectra of SN 2002fk, expanding at 11,000 km s−1 and persisting until 8 days past maximum light with a velocity of ∼9000 km s−1. SN 2002fk is characterized by a small velocity gradient of v˙Si ii = 26 km s−1 day−1, possibly caused by an off-center explosion with the ignition region oriented toward the observer. The connection between the viewing angle of an off-center explosion and the presence of C ii in the early-time spectrum suggests that the observation of Cii could be also due to a viewing angle effect. Adopting the Cepheid distance to NGC 1309 we provide the first H0 value based on near infrared (near-IR) measurements of a Type Ia supernova (SN) between 63.0 ± 0.8 (±3.4 systematic) and 66.7 ± 1.0 (±3.5 systematic) km s−1 Mpc−1, depending on the absolute magnitude/decline rate relationship adopted. It appears that the near-IR yields somewhat lower (6%–9%) H0 values than the optical. It is essential to further examine this issue by (1) expanding the sample of high-quality near-IR light curves of SNe in the Hubble flow, and (2) increasing the number of nearby SNe with near-IR SN light curves and precise Cepheid distances, which affords the promise to deliver a more precise determination of H0.