In "Myths Transformed", Âs is the original name of the Sun, which should be interpreted as meaning “warmth”.

In it Varda set the most beautiful and ardent of all spirits - Āzië, later Ārië. Attracted by the warmth and splendor of Âs, Melkor went to her and claimed Ārië as his spouse. Yet she refused him and warned him that he had no part in the light in Âs, and though his potency might destroy it, it will burn him and turn his light to darkness. In wrath, Melkor ravished her, desiring both to abase her and take her powers unto himself. But her spirit went up in a flame of anguish and wrath, and left Arda.

Thus the Sun was bereft of the light of Varda, and, stained by Melkor’s assault, it burned and cooled a while without rule, thus doing grievous harm to Arda. Yet just as Ārië had foretold, Melkor was burned, his light darkened and he could give no more light, but he was in turn pained by it ever after.

**Note : This information comes from the HoMe series of books, which means that it is considered to be from J.R.R. Tolkien's earlier, unrevised writings. Therefore, this information cannot necessarily be considered canonical.**