The type IIb supernova 2011dh from a supergiant progenitor

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 MZAMS ≳ 25M⊙. This suggests that a single star evolutionary scenario for SN 2011dh is unlikely. © 2012. The American Astronomical Society. All rights reserved.