The Sun as a magnetic star is described on the basis of recent work on solar magnetism. Observations at an arbitrary angle to the rotation axis would show a 22-year polar field variation and a 25–day equatorial sector variation. The sector variation would be similar to an oblique rotator with an angle of 90° between the magnetic and rotational axes.

Chromospheric activity, as seen by the presence of a central K2 emission in the Ca II K λ 393.4 nm line, is studied in F- and G-stars of all luminosity classes. K2 equivalent widths have been measured and corresponding absolute K2 fluxes (power per unit area at the stellar surface) calculated. Large K2 equivalent widths and thus easily detectable chromospheres occur only for stars later than about F8 but the absolute level of K2 flux does not significantly change between F0 and K0; there is no break in chromospheric activity between F- and G-stars. The apparent break, cited in the past (e.g. Wilson, 1973) is illusory and due to the observational threshold being different for different spectral classes.

Continuing our previous analysis of the chromospheric emission (Blanco et al., 1974), absolute fluxes of the K emission line have been evaluated from 10 Å mm−1 spectrograms of the O. C. Wilson collection for 31 F5-K7 main sequence stars and 172 G2-M5 giants.

About 50% of the flare events observed on red dwarfs are at least double-peaked. As the majority of flare stars are members of double or multiple systems, the possibility that time-overlapping flares originate quasi-simultaneously on the individual components is discussed.

Assuming a poissonian occurrence of flares in both components, the expected probability of observing double-peaked flares is lower than 1% for the most active binary systems.

However, from photometric observations of the double flare star EQ Peg (BD +19°5116 AB) carried out by the author with an area scanner (the components' angular separation is 3.7″) about 20% of the observed flares have been found to be double-peaked flares resulting from separate flares, one in each component. A direct flare triggering of the following flare by the preceding one can be ruled out since the light travel-time between the two components is 3.5 h, while the observed time delay between the flare peaks is about 10 min. Moreover, the proximity effect does not seem to play an important triggering role.

It is concluded that, although the analogy with solar ‘sympathetic’ flares is not always applicable, it is the most promising framework within which the majority of double-peaked flare events on red dwarfs must be interpreted.