Water Vapour in Sunspots

Abstract

FEATURES attributable to the water vapour molecule have been detected in the spectra of several late type stars during the previous decade, particularly by Woolf et al.¹, who observed in the 1.13 µm, 1.4 µm, 1.9 µm and 2.7 µm absorption bands using a balloon-borne spectrometer. Spinrad and Newburn², Wing et al.³ and Spinrad et al.⁴ have obtained coudé and Cassegrain spectra in the neighbourhood of 0.9 µm and demonstrated the great strengthening of the water vapour absorption in this region in the spectra of many stars, more especially Mira. Sinton⁵ has worked in the region 1.9 µm to 2.5 µm using a ground-based interferometer and has shown that there is water vapour absorption in the stars R Leo and χ Cyg, and McCammon et al.⁶ have also obtained spectra in this region at Mt Wilson and Palomar. Although at the low temperatures of these stars a detectable concentration of water vapour would be expected, such measurements are of interest because they provide evidence for particular atmospheric models. The purpose of this note is to present evidence for the existence of water vapour in sunspots.