High-Cadence Optical Observations of a Normal Type Ia SN 2018kp from Its Early Phase

초록

We present optical observations of a nearby Type Ia supernova (SN Ia) 2018kp on January 24 2018, +1.4 days after the estimated first light time. Its host galaxy, NGC 3367, has been under high-cadence monitoring (less than or similar to 1 day) with the purpose of providing valuable early light curves of supernovae as a primary target of the Intensive Monitoring Survey of Nearby Galaxies (IMSNG; Im et al. 2019). SN 2018kp exhibits the characteristics of a normal SN Ia, with a peak luminosity of M-B = -19.0 +/- 0.4 mag and Delta m(15)(B) = 1.19 +/- 0.03 mag, derived from our long-term light curve analysis. We estimate the host extinction to be high [E(B - V )(host) = 0.697 +/- 0.028 mag], contrasting with its sibling, SN 1986A. We estimate the mass of Ni-56 synthesized in the explosion to beM(Ni) = 0.55 +/- 0.14M(circle dot). A single power-law model (t(alpha)) describes the rising behavior of the early light curve well, with little evidence of the shock-heated cooling emission. We place upper limits on the radii of the progenitor (R-p <= 1.8 R-circle dot) and the companion star (R-c <= 1.9 R-circle dot at the optimal or R-c <= 19.2 R-circle dot at the common viewing angle, respectively) ruling out a large companion such as a red giant. Based on our data, we derive a distance to the host galaxy of 41.38 +/- 2.20 Mpc assuming that SN 2018kp follows the Phillips relation.

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