¥
Magnetic full-disk (Sun-as-a-star) indices (sunspot number,
Ca K index, W-B
effect, He 10830 equivalent width, total magnetic flux) all track the
11-year activity cycle, as expected
¥
The basal, center disk, quiet atmosphere is invariant to the
11-year cycle
(Ca K index, C 5380 equivalent width). Limb darkening is also invariant
(+-1%)
¥ The temperature-minimum layer either
tracks a 22-year cycle
or
exhibits some other as-yet-unexplained behavior (based
on
central intensities of strong photospheric Fraunhofer lines)
¥ Current
quiet-Sun model atmospheres do not support these results.