Named in memory of Walter S. Adams (1876–1956), whose spectroscopic studies of sunspots and stars led to the discovery, with A. Kohlschütter, of a spectroscopic method for determining stellar distances, the relative intensities of spectral lines being used to determine absolute magnitudes of both giant and main-sequence stars. Adams identified Sirius B as the first white-dwarf star known, and his measurement of its gravitational redshift was taken as confirming evidence for the general theory of relativity. He served as director of the Mount Wilson Observatory from 1923 to 1946. (M 15089) _ _.