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 of SN 2011dh. This is consistent with the suggestion that the yellow super-giant star detected at the location of the SN in deep pre-explosion images is the progenitor star. From the main peak of the bolometric light curve and expansion velocities we constrain the mass of the ejecta to be ≈ 2 M ⊙ , the explosion energy to be E = 6 − 10 × 10 50 erg, and the 56 Ni mass to be approximately 0.06 M ⊙ . The progenitor star was composed of a helium core of 3 to 4 M ⊙ and a thin hydrogen-rich envelope of ≈ 0.1 M ⊙ 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 25 M ⊙ . This suggests that a single star evolutionary scenario for SN 2011dh is unlikely.

Stripped-envelope (SE) supernovae (SNe) include H-poor (Type IIb), H-free (Type Ib) and He-free (Type Ic) events thought to be associated with the deaths of massive stars. The exact nature of their progenitors is a matter of debate with several lines of evidence pointing towards intermediate mass (Minit < 20 M⊙) stars in binary systems, while in other cases they may be linked to single massive Wolf-Rayet stars. Here we present the analysis of the light curves of 34 SE SNe published by the Carnegie Supernova Project (CSP-I), which are unparalleled in terms of photometric accuracy and wavelength range. Light-curve parameters are estimated through the fits of an analytical function and trends are searched for among the resulting fit parameters. Detailed inspection of the dataset suggests a tentative correlation between the peak absolute B-band magnitude and ∆m15(B), while the post maximum light curves reveals a correlation between the late-time linear slope and ∆m15. Making use of the full set of optical and near-IR photometry, combined with robust host-galaxy extinction corrections, comprehensive bolometric light curves are constructed and compared to both analytic and hydrodynamical models. This analysis finds consistent results among the two different modeling techniques and from the hydrodynamical models we obtained ejecta masses of 1.1 − 6.2 M⊙, 56 Ni masses of 0.03 − 0.35 M⊙, and explosion energies (excluding two SNe Ic-BL) of 0.25 − 3.0 × 10 51 erg. Our analysis indicates that adopting κ = 0.07 cm 2 g −1 as the mean opacity serves to be a suitable assumption when comparing Arnett-model results to those obtained from hydrodynamical calculations. We also find that adopting He I and O I line velocities to infer the expansion velocity in He-rich and He-poor SNe, respectively, provides ejecta masses relatively similar to those obtained by using the Fe II line velocities, although the use of Fe II as a diagnostic does imply higher explosion energies. The inferred range of ejecta masses are compatible with intermediate mass (MZAMS ≤ 20 M ⊙ ) progenitor stars in binary systems for the majority of SE SNe. Furthermore, our hydrodynamical modeling of the bolometric light curves suggest a significant fraction of the sample may have experienced significant mixing of 56 Ni, particularly in the case of SNe Ic.