A trend is emerging regarding the progenitor stars that give rise to the most common core-collapse supernovae ( SNe ) , those of Type II-Plateau ( II-P ) : they generally appear to be red supergiants with a limited range of initial masses , \sim 8–16 M _ { \sun } .
Here we consider another example , SN 2008cn , in the nearly face-on spiral galaxy NGCÂ 4603 .
Even with limited photometric data , it appears that SN 2008cn is not a normal SN II-P , but is of the high-luminosity subclass .
Through comparison of pre- and post-explosion images obtained with the Wide Field and Planetary Camera 2 ( WFPC2 ) onboard the Hubble Space Telescope ( HST ) , we have isolated a supergiant star prior to explosion at nearly the same position as the SN .
We provide evidence that this supergiant may well be the progenitor of the SN , although this identification is not entirely unambiguous .
This is exacerbated by the distance to the host galaxy , 33.3 Mpc , making SN 2008cn the most distant SN II-P yet for which an attempt has been made to identify a progenitor star in pre-SN images .
The progenitor candidate has a more yellow color ( [ V - I ] _ { 0 } = 0.98 mag and T _ { eff } = 5200 \pm 300 K ) than generally would be expected and , if a single star , would require that it exploded during a “ blue loop ” evolutionary phase , which is theoretically not expected to occur .
Nonetheless , we estimate an initial mass of M _ { ini } = 15 \pm 2 { M } _ { \sun } for this star , which is within the expected mass range for SNÂ II-P progenitors .
The yellower color could also arise from the blend of two or more stars , such as a red supergiant and a brighter , blue supergiant .
Such a red supergiant hidden in this blend could instead be the progenitor and would also have an initial mass within the expected progenitor mass range .
Furthermore , the yellow supergiant could be in a massive , interacting binary system , analogous to the possible yellow supergiant progenitor of the high-luminosity SN II-P 2004et .
Finally , if the yellow supergiant is not the progenitor , or is not a stellar blend or binary containing the progenitor , then we constrain any undetected progenitor star to be a red supergiant with M _ { ini } \mathrel { \hbox { \hbox to 0.0 pt { \hbox { \lower 4.0 pt \hbox { $ \sim$ } } } % \hbox { $ < $ } } } 11 { M } _ { \sun } , considering a physically more realistic scenario of explosion at the model endpoint luminosity for a rotating star .