The Strength of Quiet Sun Magnetic Fields

We present new quantitative measurements of magnetic fields on the quiet Sun. The object was (a) to measure magnetic field strengths, and (b) to test the “kilogauss model,” which posits that the apparently weak fields are actually subtelescopic knots of kilogauss fields with small filling factors. We used a new arrangement we call the spectro-videomagnetograph (SPVMG), which applies the videomagnetograph to the coude` spectrograph at Big Bear. We analyze a day’s data comprising the V signal in 8 5250 and 5247 at every point of 128 spectra, 49,200 in all. We find weak fields everywhere with mean strength of 17 Gauss and median 23.5G There are occasional network elements measuring 300-1200 Gauss. These measures are confirmed by the appropriate ratio of g-factors, the expected saturation of the stronger fields (>500G) and direct splitting measures for B>200 G. We test the models by Stenflo’s (1973) method, comparing the measured field strength in 5250 and 5234. The ratio of these measures for the 49,200 points best fits a model with filling factor unity, diverging by less than a standard deviation (SD), while the kilogauss model is 3 SD removed from agreement with the expected value. We suggest that