Observations of Extremely Cool Stars.

As one part of a program of infrared astronomy carried on at the California Institute of Technology, a survey of the sky in two infrared spectral ranges, 0.68-0.92 μand 2.01- 2.41 μ, is being carried out. The motivation for such a survey is to obtain an unbiased census of objects that emit in the 2.0-2.5-μ atmospheric window; this will, of course, include many ordinary stars, but it might also reveal many potentially interesting objects that would not be included in an a priori selection of objects to be measured. In fact, a number of strikingly red stars have already been found. Since most of these "superred" stars occur in the Milky Way, interstellar reddening may be of some consequence; but in at least a few cases the stars seem to be intrinsically extremely red. These preliminary results seem of sufficient interest to merit brief description at this time.