Abstract:
Supernova (SN) 2008bk is a well observed low-luminosity Type II event visually associated with a low-mass red-supergiant progenitor. To model SN 2008bk, we evolve a 12Msun star from the main sequence until core collapse, when it has a total mass of 9.88Msun, a He-core mass of 3.22Msun, and a radius of 502Rsun. We then artificially trigger an explosion that produces 8.29Msun of ejecta with a total energy of 2.5x10^50erg and ~0.009Msun of 56Ni. We model the subsequent evolution of the ejecta with non-Local-Thermodynamic-Equilibrium time-dependent radiative transfer. Although somewhat too luminous and energetic, this model reproduces satisfactorily the multi-band light curves and multi-epoch spectra of SN 2008bk, confirming the suitability of a low-mass massive star progenitor. As in other low-luminosity SNe II, the structured Halpha profile at the end of the plateau phase is probably caused by BaII 6496.9A rather than asphericity. We discuss the sensitivity of our results to changes in progenitor radius and mass, as well as chemical mixing. A 15% increase in progenitor radius causes a 15% increase in luminosity and a 0.2mag V-band brightening of the plateau but leaves its length unaffected. An increase in ejecta mass by 10% lengthens the plateau by ~10d. Chemical mixing introduces slight changes to the bolometric light curve, limited to the end of the plateau, but has a large impact on colours and spectra at nebular times.

The full paper is available here

To access the spectra, bolometric light curves, and multi-band light curves of the models discussed in the paper, click on the following links (each zipped tar file contains the multi-epoch spectra and a list relating model index to the time since explosion and a light curve file):

x.tgz
xr1.tgz
xr2.tgz
xm.tgz
yn1.tgz
yn2.tgz
yn3.tgz