The triple nature of the short-period RS CVn system HD 86590

Observations made at Kitt Peak show that the short-period RS CVn system HD 86590 is a triple system with a mass ratio of 0.68 derived from the radial velocity curve for the primary and secondary components. The third component has a radial velocity different from the systemic velocity for the binary system. Assuming a K0V primary places the inclination of the primary and secondary components at 78 deg and indicates that the secondary is a late K or M0 dwarf. Noting that the line strengths of the secondary and tertiary components are comparable led to the conclusion that the third component is also either a late K or early M dwarf. Such a composite of stars easily explains the discrepancy pointed out by Bolton et al. (1981) between the system's absolute magnitude and its trigonometric parallax. The H-alpha emission arises primarily from the secondary component and appears to be fairly constant with orbital phase. The primary star appears to have H-alpha filled in and its line strength appears to be variable with respect to orbital phase. The tertiary component appears to be normal (or inactive) at H-alpha.