SPECTROSCOPIC BINARY ORBITS FROM PHOTOELECTRIC RADIAL-VELOCITIES .123. 17-HYDRAE-A

17 Hydrae A, the southern member of a nearly equal double star with an angular separation of about 4'', has been variously classified as hav ing a composite or an Am-type spectrum. It is now shown to be a spectr oscopic binary with a period of Ig days and an eccentricity of 0 . 5. Those characteristics are not likely to be found in a composite-spectr um system but are acceptable for a binary with an Am primary. An appea l to other astronomers for a spectroscopic decision on the matter has brought from Toulouse a definite confirmation that both visual compone nts of 17 Hya are Am stars. The one that is the subject of this paper may be rotating pseudo-synchronously; in that case the companion is li kely to be an M dwarf, and there might be shallow eclipses, for which an ephemeris is given.