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 12 M _ { \odot } star from the main sequence until core collapse , when it has a total mass of 9.88 M _ { \odot } , a He-core mass of 3.22 M _ { \odot } , and a radius of 502 R _ { \odot } .
We then artificially trigger an explosion that produces 8.29 M _ { \odot } of ejecta with a total energy of 2.5 \times 10 ^ { 50 } erg and \sim 0.009 M _ { \odot } of ^ { 56 } N i .
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 H \alpha profile at the end of the plateau phase is probably caused by Ba ii 6496.9 Å 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 0.2 mag V -band brightening of the plateau but leaves its length unaffected .
An increase in ejecta mass by 10 % lengthens the plateau by \sim 10 d. 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 .