Abstract
Brief descriptions are given of the spectroscopic and the monochromatic observations of the umbral brightening on 29 October, 1972. The source of the brightening is attributed to the kinetic energy of the infalling coronal matter with a final velocity of 200 km s−1, into the umbral gas. The spectra of this brightening reveal many hydrogen and metallic emission lines. The variety of the widths of these lines indicates the existence of complex nonthermal velocity field and of the stratification of various emitting conditions in the umbral brightening. The kinetic energy of the falling matter would be expended not only for producing the emissions, but also for exciting the complex velocity field of nonthermal motion.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Cimino, M.: 1972, Osservatorio Astronomico di Roma, Solar Phenomena, Monthly Bulletin No. 174.
Hirayama, T.: 1971, Solar Phys. 19, 384.
Hyder, C. L.: 1967, Solar Phys. 2, 49.
Jefferies, J. T. and Orrall, F. Q.: 1961, Astrophys. J. 133, 963.
Kawaguchi, I.: 1965, Publ. Astron. Soc. Japan 16, 86.
Kawaguchi, I. and Kitai, R.: 1973, Solar Phys. 33, 145.
Kogure, T.: 1973, Private communication.
Stellmacher, G. and Wiehr, E.: 1970, Astron. Astrophys. 7, 432.
Tanaka, K.: 1971, Publ. Astron. Soc. Japan 23, 185.
Waldmeier, M.: 1961, Z. Astrophys. 53, 198.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Kubota, J., Tamenaga, T., Kawaguchi, I. et al. The brightening of sunspot umbra observed on 29 October, 1972. Sol Phys 38, 389–398 (1974). https://doi.org/10.1007/BF00155076
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00155076