Solar luminosity variation. III. Calcium K variation from solar minimum to maximum in cycle 21

摘要: Measurement of the full disk Ca II H and K profiles has now been completed from minimum to maximum in current solar cycle 21. The central intensity line increases by 30% on average, but a peak change +40% was recorded near activity late 1979. 1 A index shows corresponding smaller increase 18%. These changes Sun viewed as star appear be directly attributable occurrence plages visible hemisphere. Similar measurements 1' x 3' quiet region at center show no significant systematic variability. This suggests that network long-term variability rising phase cycle. widths asymmetries also associated with degree activity. In general, spectral features formed above temperature are all closely correlated their variablitity, they not well related strength narrow photospheric lines K/sub 1/ wings. correlates very plage index, Zurich sunspot number, Ottawa 10more » cm flux measurements. observing program will continue into declining 21, so we have opportunity test constancy our correlations different when rate formation is decreasing may influenced more remnants active regions earlier.« less