What are the signs of a star about to go super nova?
Good question, few answers, but good read:
http://www.huffingtonpost.com/2013/02/12/supernova-warning-explosion-star-death_n_2668510.html
I believe they have to ‘burn’ through all of their ‘fuel’, and then they light up, or something like that. Many believe that it has, or is about to happen to Betelgeuse {one of the shoulders of Orion} Of course, if it happened tomorrow, we wouldn’t know for a few hundred or so years, given the distance.
See:
Supernova: Five Stages in the Death of a Star
http://www-astro.physics.ox.ac.uk/~podsi/SN_sketch5.pdf
Initial Stages of Supernova Explosion Finally Observed
http://news.softpedia.com/news/Initial-Stages-of-Supernova-Explosion-Finally-Observed-240817.shtml