A&A 404, 637-643 (2003)
DOI: 10.1051/0004-6361:20030517
A comparison between the X-ray variable Sun and solar-like main sequence stars
G. Micela1 and A. Marino21 INAF, Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
2 Dipartimento di Scienze Fisiche e Astronomiche - Università di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
(Received 7 January 2003 / Accepted 21 March 2003)
Abstract
We analyze the time variations of the solar X-ray luminosity observed
with Yohkoh/SXT with the aim to compare the X-ray variability of the
Sun with that of the other solar-like main sequence stars as
function of the relevant time scales. Since the observational set-up
and strategies used to observe the Sun differ from those used for the
other stars, we have explored the solar X-ray variability properties
starting from the available solar data, trying to reproduce the
observational procedures adopted for the stars. We have quantified how
the solar variability amplitude increases with the explored time scales
and found that solar-cycle variability can contribute at most up
to 60% to the spread observed in nearby solar-like star X-ray luminosity
distribution functions. The comparison between the Sun and the nearby
stars is consistent with a scenario in which a fraction of moderately
active stars (
erg/s) have X-ray variability similar
to the Sun, while more active stars lack solar-like cyclic coronal
activity.
Key words: Sun: corona -- stars: coronae -- X-rays: stars
Offprint request: G. Micela, giusi@astropa.unipa.it
© ESO 2003