So, you have the big bad race, whose extermination method is basically to force stars to go supercritical via the power of handwavium. You can assume 1 solar mass for each, but you can change it if you like.
The first scenario would be:
- Star A of the binary swells to red giant status, and then is either touching or consumes star B: what would happen?
- Star A goes supernova, with maybe 1 AU of distance between it and Star B.
What info Id like to know:
- Can it destroy the other star via supernova?
- What is the effective range of the supernova, and can it destroy stars a light year or more away?