A circle of stars often represents , and harmony in flags,seals and signs, and is also seen in iconographic motifs related to the Woman of the Apocalypse as well as in Baroque allegoric art that sometimes depicts the Crown of Immortality.
The New Testament's Book of Revelation (12:1, 2 & 5) describes the Woman of the Apocalypse: And there appeared a great wonder in heaven; a woman clothed with the sun, and the moon under her feet, and upon her head a crown of twelve stars. And she being with child cried, travailing in birth .... And she brought forth a man child, who was to rule all nations with a rod of iron:and her child was caught up unto God, and to his throne In Catholic tradition she has been identified with the Blessed Virgin Mary, especially in connection with the Immaculate Conception. Mary is often pictured with a crown or Circle of Stars.
The doctrine of the Immaculate Conception was somewhat controversial in the medieval church, and the liturgical Office for the feast was only established in 1615. In 1649, Francisco Pacheco (father-in-law of Velázquez) published his Art of Painting firmly establishing the detailed correct iconography for paintings of the Virgin of the Immaculate Conception, which included the circle of stars (he also advised the inquisition in Seville on artistic matters). This was followed by Murillo and his school in very many paintings, and influenced non-Spanish depictions.