A binary model for the infrared source HD 101584

HD 101584 is a peculiar infrared source with the visual spectrum of a luminous F supergiant. Sufficient velocity data are available to yield a preliminary orbit with a period of about 3.5 years and a mass function of 0.25 M/sub sun/. The excess infrared radiation is attributed to an unseen cool companion which has filled its Roche lobe and is losing mass. Some of this mass is visible (from the Ca ii lines) as a gas stream flowing toward the warmer star where it has formed a shell producing the F supergiant spectrum. Limits on the masses and radii of the two stars are derived in the paper