Nova defeats Heimdall
Heimdall, a standard Asgardian warrior only possesses limited super strength, about 30 tons, his skin is only about 3 times as dense as a human, and other superhuman physical attributes.
Nova, possesses the Nova force, flight, enhanced strenght, speed and durability. His suit allows protection from harsh weather conditions and the ability to breathe in space.
This match comes down to heimdall's super senses, vision and hearing and Nova's use of the Nova force. Quite simply put, Nova wins quite easily as he outclasses heimdall in Speed and agility thanks to the Nova force and he eloquently put, hits real hard. Heimdall being an Asgardian warrior will put up a real good fight, and its commeneded but Nova outclasses him in every way possible. It should also be noted that nova's helmet is able to pick up radio and heat transmissions so Heimdall isnt able to outclass him in the sense department. The asgardian is able to move fast and take a lot of hits, but Nova hits harder and is faster. Simply put, while we'll get a good match up and Nova will take a couple of good hits, Nova will come out on top.