Caccin, B. and Penza, V. (2002) Line ratios and temperature structure in the deep photosphere. Il nuovo cimento C, 25 (5\6). pp. 573-579. ISSN 1826-9885
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Abstract
A program to monitor solar cycle variations of the solar flux by using suitable spectral line ratios is going on at Kitt Peak since 1976;the most sensitive to Teff variations are the ratios involving the C I 538.032 nm, whose formation depth is almost coincident with that of the continuum, and either the Fe I 537.958 or the Ti II 538.103. The temperature sensitivities of those line ratios have been empirically calibrated by observing the spectra of several solar-like stars by Gray and Livingston, while several attempts to obtain the same calibration theoretically, through Kurucz’s models of stellar atmospheres, showed difficulty in reproducing quantitatively the experimental results. Because the observed/computed ratio was approximately the same for both couples of lines, we argued that the problem was in the behaviour of C line, that is more affected than the others by the temperature structure of the deep photosphere, where it is formed. As, in these layers, the gradients of the average temperature are sensibly affected by different treatments of the convection, we compared, first of all, several theoretical models, distinguished from each other in including or not convective overshooting. Then we explored the effects due to variations of the value of the free parameter (α =�/HP ) and those ensued by different versions of the mixing-length theory.
| Item Type: | Article |
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| Additional Information: | Paper presented at the International Meeting on THEMIS and the New Frontiers of Solar Atmosphere Dynamics, Rome, Italy, March 19-21, 2001. |
| Uncontrolled Keywords: | Stellar atmospheres (photospheres, chromospheres, coronae, magnetospheres); radioactiv e transfer;opacit y and line formation ; Luminosities;magnitudes;effectiv e temperatures, colors, and spectral classification ; Particle radiation, solar wind ; Conference proceedings |
| Subjects: | 500 Scienze naturali e Matematica > 530 Fisica |
| Depositing User: | Marina Spanti |
| Date Deposited: | 12 Mar 2020 14:32 |
| Last Modified: | 12 Mar 2020 14:32 |
| URI: | http://eprints.bice.rm.cnr.it/id/eprint/14848 |
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