Although not a carrier vessel, Columbia is equipped with a squadron of fighters and bombers, which are docked in special docking ports on both sides of the ship. Fighters and Bombers are usually used in ship to ship battles.
When Columbia attacks an enemy vessel, she does not only rely on her fighters, but on her torpedo launchers and her massive particle canons mounted on the front of the ship.
To defend herself, Columbia uses a standard defense-grid-system of, which is mounted in pairs around the ships main hull.
Aries-class ships are preffered used to attack planets or / and build a blockade around them. Therefor the class features a huge railgun for planetary bombardement.
Aries-class frigates do also support ground attacks by providing battleforces to a planets surface. The ships can launch two command-pods. The Pods there serve as support and command facilities.
Beside troops and ground vehicles the pods carry a Janeway-Class transport.
Another shinning example of your spectacular style. Your work is so clean, well thought out, and perfectly proportioned. Top notch! BTW check out El Barto's suggestion. I know these would be even more perfect if you had the right background to make them really pop.
Killer ship, Dude! Ever think about getting into photoediting? You know, getting your ship into 'space'. There's a group if you're interested, it's not really that complicated and would add a lot to this build. http://www.mocpages.com/group.php/13655