Solar spectral fine structure in 18 - 23 GHz band.

Cecatto, J. R., K. R. Subramanian, and H. S. Sawant, Solar spectral fine structure in 18 - 23 GHz band., Brazilian Journal of Physics, 29, 510-515 (1999) (ADS)

The cartoon

(click on the image for a larger version)

This cartoon is an example of the complexities of solar radio astronomy, which combines what looks like hopelessly ambiguous geometrical interpretations with, at the same time, very precise knowledge of frequency vs time. In this case the authors find an explanation for their time structures in the 6th harmonic of the local gyrofrequency. Note the caixa preta at loop top. Also note how blithely the "escape level of 21 GHz emission" ignores the the structural details of field and plasma density as they vary across the loop structures.

      "Loop-loop interactions" is a common theme in the Archive, and this cartoon shows a seemingly erroneous tangency of two loops to imply that. This might be possible if the currents carried by the loops were "neutralized", as in the solar interior, by sheath currents wrapping around them. Otherwise one would have to show magnetized space between the loops; this is the other kind of current (non-neutralized). This kind of current makes more sense observationally but does not fit well into an MHD description.

Date: 2010 June 16

Update: 2019 November 19