VY Canis Majoris. IV. The emission bands of ScO

The emission features in VY CMa near 6036, 6079 A were discovered by Wallerstein in 1962 and later identified with ScO, independently, by Herbig and by Wallerstein. The recent laboratory analyses of the blue-green system of ScO by Adams, Klemperer, and Dunn, and of the orange system by Stringat, Athenour, and Fe me nias, have been used to compute theoretical profiles for the unresolved ScO 00 band of the A 2ll-x 2 (orange) system, under assumptions of LTE and optical thinness. The sharply peaked, almost linelike structure in VY CMa is shown to be due to the crowding of rotational structure near the band heads, on account of a very low rotational temperature; values of about 380 K in 1962 and 820 in 1966 were obtained by comparing the relative intensities of the 6036, 6079 A peaks with theoretical prediction. Subject headings: infrared sources - molecules - stars, individual