The Type IIb Supernova 2011dh from a Supergiant Progenitor
Nomoto, Ken'ichi; Fraser, Morgan; Sollerman, Jesper; Benetti, Stefano; Kotak, Rubina; Ergon, Mattias; Folatelli, Gastón; Maeda, Keiichi; Bersten, Melina C.; Botticella, Maria Teresa; Tomasella, Lina; Ochner, Paolo; Benvenuto, Omar G.
Japan, Argentina, Sweden, Italy, United Kingdom
Abstract
A set of hydrodynamical models based on stellar evolutionary progenitors is used to study the nature of SN 2011dh. Our modeling suggests that a large progenitor star—with R ~ 200 R ⊙—is needed to reproduce the early light curve (LC) of SN 2011dh. This is consistent with the suggestion that the yellow super-giant star detected at the location of the supernova (SN) in deep pre-explosion images is the progenitor star. From the main peak of the bolometric LC and expansion velocities, we constrain the mass of the ejecta to be ≈2 M ⊙, the explosion energy to be E = (6-10) × 1050 erg, and the 56Ni mass to be approximately 0.06 M ⊙. The progenitor star was composed of a helium core of 3-4 M ⊙ and a thin hydrogen-rich envelope of ≈0.1M ⊙ with a main-sequence mass estimated to be in the range of 12-15 M ⊙. Our models rule out progenitors with helium-core masses larger than 8 M ⊙, which correspond to M ZAMS >~ 25M ⊙. This suggests that a single star evolutionary scenario for SN 2011dh is unlikely.