I'm trying to find a movie where a crew of students "cadets" on a "corvette" class ship are attacked by an enemy force and after the ships supervisors die in the battle, the cadets chose to keep fighting, they are outnumbered, and use different methods to thin down enemy numbers until reinforcements can arrive. Their last trick is to hide on a comets trail to avoid detection...

Any ideas?

It sounds like wing commander.
Ref:
Wing Commander (1999)

Were they fighting the Kilrathi ?

No it's not wing commander, it may have come out around the same time, it was a made for TV movie from what I remember.

thanks for the suggestion but I already checked wing commander =( should have probably mentioned that.

I'm guessing Star Command from 1996. It's pretty obscure.

That;s the one :) Purukivel rules :)

Thanks from me too, Quinn realized I was looking for the same movie.