This will be a rather short entry but if you've been following the Supernova in M51 called SN2011dh, or observing it, then this paper by some rather famous astro-physicists/astronomers is rather interesting. It is published by Cornell University and can be found in this link. Simply go to the upper right and click on the PDF to download a copy to read. The paper identifies the
progenitor star, that it is a Type IIb or transitional TypeII/Ib, and is very similar to SN 1993J which happened in M81. It is probably a 18 to 21 solar masses and likely to have been bluer than a red supergiant that would explode as a Type II Plateau SNe. The article also explores if this could be an explosion from a binary system.
Want more, go read the article. It is rather fascinating and one I'll try to follow the updates over time as the supernova lessens in terms of brightness and the pros do more work on it. Fascinating stuff and something I need to see if I can get my students involved with, even if it is simply going through images to try and identify former SN's. I guess Zoo would have something like that, I just need to head over and get to work there again (I took the last 3 months off from Galaxy Zoo).
Note that SN2011dh is now listed as mag. 12.3, and with the moon getting out of the way that is sufficient for many amateurs with medium size scopes to get a peek at this. My goal is to sketch is this week each night that the sky is clear and keep that up until it fades. It won't do anyone but me any good since everyone uses imaging, but visual observations are what I do so I'll keep a journal of the observations.