The astral body is, in the seven-layer aura model, the fourth layer, often placed at the midpoint of the seven as a bridge between the lower, more physical layers and the higher, more spiritual ones, and associated with love, relationship and the connection between people. The term "astral" is old in Western occultism, denoting a subtle "star" body, and it was given prominence by the Theosophists, from whom the modern aura literature, including Barbara Brennan's influential synthesis, took it.
In some schemes the astral layer is where out-of-body experience and the "astral travel" of occult tradition are located. As the transitional layer it is read as the level at which the personal and the spiritual meet. The seven-layer aura is a modern esoteric model, developed through Theosophy and the later New Age movement from older Indian and Western subtle-body ideas; it is described here as part of a belief tradition, with no scientific standing, no anatomical reality demonstrated, and no medical or diagnostic claim made for it.
Sources Hands of Light: A Guide to Healing Through the Human Energy FieldBarbara Ann Brennan with Rainbow Body: A History of the Western Chakra System from Blavatsky to BrennanKurt Leland