(1). It was rapidly shown to be a type II-Plateau (II-P) supernova which was discovered about 87 days after explosion (2-5). The progenitors of type II-P supernovae have long been thought to be red supergiant stars with initial masses greater than 8-10M ! that have retained their hydrogen envelopes before core-collapse. This model accounts for the 2 to 3 month long plateau phases seen in the lightcurves of SNe II-P, the existence of hydrogen P-Cygni profiles in the early time spectra and the estimated
We present photometric and spectroscopic data of the Type II‐P supernova (SN II‐P) 2003gd, which was discovered in M74 close to the end of its plateau phase. SN 2003gd is the first Type II supernova (SN) to have a directly confirmed red supergiant (RSG) progenitor. We compare SN 2003gd to SN 1999em, a similar SN II‐P, and estimate an explosion date of 2003 March 18. We determine a reddening towards the SN of E(B−V) = 0.14 ± 0.06, using three different methods. We also calculate three new distances to M74 of 9.6 ± 2.8, 7.7 ± 1.7 and 9.6 ± 2.2 Mpc. The former was estimated using the standard candle method (SCM), for Type II supernovae (SNe II), and the latter two using the brightest supergiants method (BSM). When combined with existing kinematic and BSM distance estimates, we derive a mean value of 9.3 ± 1.8 Mpc. SN 2003gd was found to have a lower tail luminosity compared with other normal Type II‐P supernovae (SNe II‐P) bringing into question the nature of this SN. We present a discussion concluding that this is a normal SN II‐P, which is consistent with the observed progenitor mass of 8+4−2 M⊙.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.