Solar luminosity variation. I. C I 5380 as a temperature indicator and a search for global oscillations.
Abstract
The high-excitation, weak Fraunhofer line C 1 5380.3 A is shown to originate within the same photospheric layers as the Sun's continuous radiation. By monitoring the central depth of the C I line relative to the local continuum, in unfocused sunlight, we may follow temperature, and hence luminosity changes of the whole Sun as a function of time. The technique is practically insensitive to telluric absorption effects and instrumental spectral response. A power spectrum analysis of 100 hours of observations reveals no dominant oscillation of period P rising above the 3 a uncertainty limit of 0.4 K for m < p < 60 . For power at 2h40m the limit is 1.0 K; for 5h20m, 2.0 K. The day-to-day fluctuation for a 3 month period is 0.85 K rms (which corresponds to 0.06% in the solar constant, or 0.0006 mag in luminosity). Subject headings: Sun: atmospheric motions - Sun: general
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1977
- DOI:
- 10.1086/154929
- Bibcode:
- 1977ApJ...211..281L
- Keywords:
-
- Fraunhofer Lines;
- Luminous Intensity;
- Power Spectra;
- Solar Radiation;
- Solar Temperature;
- Atmospheric Attenuation;
- Atmospheric Circulation;
- Oscillating Flow;
- Solar Atmosphere;
- Solar Granulation;
- Solar Spectra;
- Spectrum Analysis;
- Solar Physics