Volume 578, June 2015
|Number of page(s)||4|
|Published online||16 June 2015|
The coronal temperatures of low-mass main-sequence stars
University of Vienna, Department of Astrophysics,
Accepted: 29 April 2015
Aims. We study the X-ray emission of low-mass main-sequence stars to derive a reliable general scaling law between coronal temperature and the level of X-ray activity.
Methods. We collect ROSAT measurements of hardness ratios and X-ray luminosities for a large sample of stars to derive which stellar X-ray emission parameter is most closely correlated with coronal temperature. We calculate average coronal temperatures for a sample of 24 low-mass main-sequence stars with measured emission measure distributions (EMDs) collected from the literature. These EMDs are based on high-resolution X-ray spectra measured by XMM-Newton and Chandra.
Results. We confirm that there is one universal scaling relation between coronal average temperature and surface X-ray flux, FX, that applies to all low-mass main-sequence stars. We find that coronal temperature is related to FX by T̅cor = 0.11 FX0.26, where T̅cor is in MK and FX is in erg s-1 cm-2.
Key words: Sun: corona / Sun: X-rays, gamma rays / stars: activity / stars: coronae / stars: low-mass / X-rays: stars
© ESO, 2015
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