What is astral body?

The astral body is the subtle body which is within this physical body like the bladder of a football. It is an exact counterpart of the physical body. It is made up of the five organs of action, the five organs of knowledge, the five Pranas, mind, intellect, Chitta or the subconscious mind, and Ahankar or egoism. Some call it "the double". It is this astral body that comes out of the physical body after death and moves to heaven. Death of this astral body through the knowledge of the Eternal frees one from the cycle of births and deaths.

Swami Sivananda