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Science 8 October 1993:
Vol. 262. no. 5131, pp. 215 - 218
DOI: 10.1126/science.262.5131.215
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Articles

A Spatially Resolved X-ray Image of a Star Like the Sun

J. H. M. M. Schmitt 1 and M. Kürster 1

1 Max-Planck-Institut für Extraterrestrische Physik, 85740 Garching, Federal Republic of Germany

Observations made with the x-ray satellite ROSAT (Roentgen Satellite) have produced the first spatially resolved x-ray image of a corona around a star like our sun. The star is the secondary in the eclipsing binary system agr Coronae Borealis (CrB), which consists of one star of spectral type A0V and one of type G5V. The x-ray light curve of agr CrB shows a total x-ray eclipse during secondary optical minimum, with the G star behind the A star. The totality of the eclipse demonstrates that the A-type component in agr CrB is x-ray dark and that the x-ray flux arises exclusively from the later-type companion. The x-ray eclipse ingress and egress are highly asymmetric compared with the optical eclipse, indicating a highly asymmetric x-ray intensity distribution on the surface of the G star. From a detailed modeling of the ingress and egress of the x-ray light curve, an eclipse map of the G star was constructed by a method based on an optimization by simulated annealing.

Submitted on May 6, 1993
Accepted on August 11, 1993


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
A Spectroscopic Measurement of the Coronal Density of Procyon.
J. H. M. M. Schmitt, B. M. Haisch, and J. J. Drake (1994)
Science 265, 1420-1422
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