A large coronal loop in the Algol system

作者：Peterson W M^*; Mutel R L; Guedel M; Goss W M

来源：Nature, 2010, 463(7278): 207-209.

DOI：10.1038/nature08643

The close binary Algol system contains a radio-bright KIV sub-giant star in a very close (0.062 astronomical units) and rapid (2.86 day) orbit with a main sequence B8 star. Because the rotation periods of the two stars are tidally locked to the orbital period, the rapid rotation drives a magnetic dynamo. A large body of evidence points to the existence of an extended, complex coronal magnetosphere originating at the cooler K subgiant(1-4). The detailed morphology of the subgiant's corona and its possible interaction with its companion are unknown, though theory predicts that the coronal plasma should be confined in a magnetic loop structure(5), as seen on the Sun. Here we report multi-epoch radio imaging of the Algol system, in which we see a large, persistent coronal loop approximately one subgiant diameter in height, whose base is straddling the subgiant and whose apex is oriented towards the B8 star. This suggests that a persistent asymmetric magnetic field structure is aligned between the two stars. The loop is larger than anticipated theoretically(6,7), but the size may be the result of a magnetic interaction between the two stars.

• 出版日期2010-1-14