Solar Luminosity Variation. V. The Photospheric Lines 1976--1985

Kitt Peak full-disk spectrophotometric records for selected spectrum lines observed during the period 1976-1985 are analyzed using improved corrections for water vapor and an instrument slit change. The equivalent width of the ground state line of Mn I 5394.7 A shows the greatest variability and correlates well with Ca K 3933 A intensity. Temperature-sensitive C I 5380.3 A, after some apparently nonthermal activity in 1976-1978, settles down to a near constant level. The equivalent widths of other lines show little or no change with time. Evidence is presented that the source of the variability in Mn I 5394.7 A is not confined to solar plage regions alone. The annual means in the central depth of C I 5380.3 A, interpreted as indicative of fluctuations in T(eff), show a peak-to-peak variation of 0.7 K over 1979-1985.