2 research outputs found
Latitudinal variation of the solar photospheric intensity
We have examined images from the Precision Solar Photometric Telescope (PSPT)
at the Mauna Loa Solar Observatory (MLSO) in search of latitudinal variation in
the solar photospheric intensity. Along with the expected brightening of the
solar activity belts, we have found a weak enhancement of the mean continuum
intensity at polar latitudes (continuum intensity enhancement
corresponding to a brightness temperature enhancement of ).
This appears to be thermal in origin and not due to a polar accumulation of
weak magnetic elements, with both the continuum and CaIIK intensity
distributions shifted towards higher values with little change in shape from
their mid-latitude distributions. Since the enhancement is of low spatial
frequency and of very small amplitude it is difficult to separate from
systematic instrumental and processing errors. We provide a thorough discussion
of these and conclude that the measurement captures real solar latitudinal
intensity variations.Comment: 24 pages, 8 figs, accepted in Ap