Abstract
A study of the solar spectrum near helium 10 830 Å has shown that, where the line is very weak, the anomalous ratio of the two components is due almost certainly to faint blends. The centre-limb intensity variation over supergranule centres is in good agreement with an optically-thin law. The line is stronger over supergranule boundaries, and the ratio of the two components can be understood only if the absorbing elements have been resolved incompletely (as is probable); using centre-limb intensity variations, we have been unable to distinguish between unresolved horizontal platelets or inclined slabs.
The integrated absorption in 10 830 Å over supergranule centres is double that at the boundaries. An analysis of the extension of 10 830 Å beyond the limb has failed to reveal the relative contributions from these two regions or their variations with height (though the supergranule-centre emission should be located relatively low). Line profiles in 10 830 Å, hydrogen Paγ and Caii 8542 Å indicate that, out to at least 5000 km, line broadening is effectively non-thermal, with horizontal rms velocities of about 20 km s−1.
Similar content being viewed by others
References
Athay, R. G.: 1963,Astrophys. J. 137, 931.
Beckers, J. M.: 1963,Astrophys. J. 138, 648.
Breckinridge, J. B. and Hall, D. N. B.: 1973,Solar Phys. 28, 15.
De Jager, C.: 1959,Handbuch Physik 52, 80.
De Jager, C., Namba, O., and Neven, L.: 1966,Bull. Astron. Inst. Neth. 18, 128.
Giovanelli, R. G., Hall, D. N. B., and Harvey, J. W.: 1972,Solar Phys. 22, 53.
Giovanelli, R. G., Michard, R., and Mouradian, Z.: 1965,Ann. Astrophys. 28, 871.
Gulyaev, R. A.: 1964,Astron. Zh. 41, 313 (Soviet Astron. 8, 243).
Harvey, J. and Hall, D. N. B.: 1971, in Howard, R. (ed.), ‘Solar Magnetic Fields’,IAU Symp. 43, 279.
Jefferies, J. T.: 1968,Spectral Line Formation, Blaisdell, Waltham, Toronto, and London.
Kononovich, E. V.: 1961,Astron. Zh. 38, 218 (Soviet Astron. 5, 165).
Mouradian, Z.: 1965,Ann. Astrophys. 28, 805.
Namba, O.: 1963,Bull. Astron. Inst. Neth. 17, 93.
Nguyen, Ngan: 1970,Astron. Zh. 47, 351 (Soviet Astron. 14, 283).
Nikol'skaya, K. I.: 1966,Astron. Zh. 43, 936 (Soviet Astron. 10, 751).
Nikol'skaya, K. I.: 1967,Astron. Zh. 43, 1043 (Soviet Astron. 11, 839).
Perepelkin, E. Ya. and Melnikov, O. A.: 1935,Izv. Pulkovo Observ. 14, No. 122, 1.
Redman, R. O. and Suemoto, Z.: 1954,Monthly Notices Roy. Astron. Soc. 114, 524.
Suemoto, Z.: 1963,Publ. Astron. Soc. Japan 15, 531.
Author information
Authors and Affiliations
Additional information
Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.
Rights and permissions
About this article
Cite this article
Giovanelli, R.G., Hall, D. The helium 10830 Å line in the undisturbed chromosphere. Sol Phys 52, 211–228 (1977). https://doi.org/10.1007/BF00935803
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00935803