2003ApJ...598.1387P

We use soft X-ray and magnetic field observations of the Sun (quiet Sun, X-ray bright points, active regions, and integrated solar disk) and active stars (dwarf and pre-main-sequence) to study the relationship between total unsigned magnetic flux, Φ, and X-ray spectral radiance, L_X. We find that Φ and L_Xexhibit a very nearly linear relationship over 12 orders of magnitude, albeit with significant levels of scatter. This suggests a universal relationship between magnetic flux and the power dissipated through coronal heating. If the relationship can be assumed linear, it is consistent with an average volumetric heating rate Q{d1}∼B{d1}/L, where B{d1} is the average field strength along a closed field line and L is its length between footpoints. The Φ-L_Xrelationship also indicates that X-rays provide a useful proxy for the magnetic flux on stars when magnetic measurements are unavailable.