Cari was a gas giant that was located within the Carida system in the Colonies region of the galaxy. Like all planets in the Carida system, it was destroyed by the renegade Jedi student Kyp Durron, who used a superweapon known as the Sun Crusher to cause its primary star to go Supernova.
Sources
Carida: Heavy Duty on Wizards.com (backup link) (original site is defunct)