system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] What would have happened if they firedfired the Death Star's main cannon at the gas giant at the end of the original movie?

Would the planet tank it? Would it give the presumably metallic hydrogen core enough energy to temporarily light up?

I'm guessing the former since making a planet go boom isn't nearly the kind of power needed to JumpStart a gas giant into a freaking Star.
gpt
The energy given to Alderaan was about 10^38 joules. If the gas giant is the size of Jupiter, its gravitational binding energy will be about 2X10^36 joules, 500 times less. So, it won't tank the explosion. However, the gas giant will explode slower, at an average speed of about 300km/s.