I am considering a scenario where people are anticipating the star of their system going supernova, which would be somehow triggered by an advanced, hostile alien race. However, the people cannot predict when it will happen. Their best option is to prepare some temporary shelter they can stay in until people from other systems can come extract them after the brunt of the explosion has passed.
I considered them building bunkers deep underground that could shield them from radiation for a few days or weeks until help arrives.
Is this a realistic way at all to temporarily protect yourself from your own star’s explosion? Or, would the planet heat up all the way through, making the underground unsafe? Or, would the planet just be completely destroyed? Taking into account planet size, distance from the star, size of the star, and radiation shielding technologies.
In addition, as the supernova would be triggered by a hostile alien force, there is the possibility that its power may not be equal to that of a natural supernova.
If not, any ideas for more realistic options of escape/defense in this situation? (Or some other stellar phenomenon that an underground bunker might be reasonable for?)