The Far-Infrared and X-Ray Radiation of Active Late-Type Stars: Suggestions for Strong Spottedness

The IRAS observations and the X-ray data of active late-type stars are compared with recent measurements of magnetic fields. The deviations of the fluxes observed at the 12-micron band from those predicted by blackbody radiation in the visible for active K and M stars show a correlation with the values of observed magnetic fluxes. The L(x)/L(bol) ratio increases considerably for stars with large IR excess. All these features could be understood if we assume that stellar surfaces are spotted more heavily than follows from the analysis of rotational modulation of optical emission.