SN2017jgh: a high-cadence complete shock cooling light curve of a SN IIb with the Kepler telescope

SN 2017jgh is a type IIb supernova discovered by Pan-STARRS during the C16/C17 campaigns of the Kepler/K2 mission. Here, we present the Kepler/K2 and ground based observations of SN 2017jgh, which captured the shock cooling of the progenitor shock breakout with an unprecedented cadence. This event presents a unique opportunity to investigate the progenitors of stripped envelope supernovae. By fitting analytical models to the SN 2017jgh light curve, we find that the progenitor of SN 2017jgh was likely a yellow supergiant with an envelope radius of similar to 50-290 R-circle dot, and an envelope mass of similar to 0-1.7 M-circle dot. SN 2017jgh likely had a shock velocity of similar to 7500-10 300 km s(-1). Additionally, we use the light curve of SN 2017jgh to investigate how early observations of the rise contribute to constraints on progenitor models. Fitting just the ground based observations, we find an envelope radius of similar to 50-330 R-circle dot, an envelope mass of similar to 0.3-1.7 M-circle dot and a shock velocity of similar to 9000-15 000 km s(-1). Without the rise, the explosion time cannot be well constrained that leads to a systematic offset in the velocity parameter and larger uncertainties in the mass and radius. Therefore, it is likely that progenitor property estimates through these models may have larger systematic uncertainties than previously calculated.

Automated summary

SN 2017jgh, discovered by Pan-STARRS during the Kepler/K2 mission, likely had a progenitor yellow supergiant with an envelope radius between 50-290 solar radii and an envelope mass between 0-1.7 solar masses. The shock velocity of SN 2017jgh was estimated to be between 7500-10,300 km/s. The study also showed that estimates of progenitor properties through analytical models may have larger systematic uncertainties than previously calculated.