Infrared stars in binary systems.

The peculiar A- and F-type supergiants, RD 101384, 89 Her, v Sgr, and R CrB have large and unusual infrared excesses which may be due to the presence of a very cool companion. In RD 101384 (F2e lap) more energy is radiated in the infrared than by the visible star. We suggest that the infrared energy is produced by an M supergiant companion instead of thermal reradiation by dust. RD 101384 also has a variable radial velocity with an amplitude of 20 km -i A P Cygni profile is observed at H and during two years the Ca ii H- and K-lines had more negative velocities by 30 km 1 from other lines. The stars 89 Her (F2e Ia) and v Sgr (cApe) show infrared excesses similar to RD 101384 which may also be produced by a very cool star. The peculiar carbon-rich star R CrB (F8pep) has an infrared excess closely resembling the Cygnid-type infrared objects. R CrB also has a regular light curve at 3.3 like the long-period variables. The infrared companion may be responsible in someway for this star's erratic behavior in the visual region. Sabject headings: binaries - infrared - luminous stars