A bright x-ray and radio corona on the F0V star 47 Cas

摘要

X-ray and microwave observations of the nearby A7-F0V star 47 Cas reveal indications for extraordinarily strong coronal activity, characterized by X-ray and radio luminosities of L(sub X) = 2.90 x 10(exp 30) erg/s and L(sub R) = 1.1 x 10(exp 15) erg/s/Hz, respectively, and the presence of very strong X-ray flares. The rapidly rotating star is not known to possess a spectroscopic companion that may be held responsible for the observed emissions. Interpreting the X-ray modulation as rotational modulation and combining the value of the rotation period with the optically determined v(sin)i, the stellar radius is found to be consistent with the photometrically determined radius. This may be the first non-interacting, early F V star discovered as a strong, nonthermal radio source. From kinematic arguments, 47 Cas is a likely member of the Pleiades Moving Group, and may thus be very young.