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| Content Provider | Springer Nature Link |
|---|---|
| Author | Livingston, W. Wallace, L. |
| Copyright Year | 2003 |
| Abstract | We employ limb darkening, spectral energy distribution (color), and center-disk spectrum line strength to investigate photospheric temporal variability. Current limb-darkening curves agree to 1% with past observations taken at different epochs extending back to 1975. Concerning color, from the data of Labs and Neckel (Cox, 1999) we deduce that the solar limb is 1000 Å more red than disk center. But when integrated over the entire disk to represent the Sun-as-a-star, the color shift is only 30 Å. Color is therefore not a very sensitive indicator of full-disk photospheric change. We examine the center-disk time series for C 5380 Å and Fe 5379 Å equivalent width and the Ca K index. The ratio C 5380/Fe 5379 in equivalent width is 0.4221+0.00011 (± 0.00003) y $^{−1}$, indicating secular change but with no cycle modulation. Converted to temperature this variance amounts to ± 0.028 K. This is in contrast to the full-disk cycle modulation of these lines reported by Gray and Livingston (1997b). Ca K index also exhibits no cycle variation at disk center. Taking into account these findings, plus the small fraction of the photosphere occupied by magnetic elements as revealed in high-resolution G-band pictures, we suggest that cycle magnetic fields thread through the basal atmosphere without physical effect; that the basal quiet atmosphere is observationally immutable to the magnetic cycle within the limits given above. |
| Starting Page | 227 |
| Ending Page | 237 |
| Page Count | 11 |
| File Format | |
| ISSN | 00380938 |
| Journal | Solar Physics |
| Volume Number | 212 |
| Issue Number | 2 |
| e-ISSN | 1573093X |
| Language | English |
| Publisher | Kluwer Academic Publishers |
| Publisher Date | 2003-01-01 |
| Publisher Place | Dordrecht |
| Access Restriction | One Nation One Subscription (ONOS) |
| Subject Keyword | Astrophysics |
| Content Type | Text |
| Resource Type | Article |
| Subject | Astronomy and Astrophysics Space and Planetary Science |
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