Abstract
We obtained simultaneous spectra with a spatial resolution of 1/2″ and a temporal resolution of 15 s in Hα, Ca ii-K, Caii 8542 Å, and three Fei lines of the sunspot group responsible for the large flares of August, 1972 (McMath No. 11976). A time series taken 1972, August 3 in the Fei 6173 Å Zeeman sensitive line was analyzed for oscillations of field strength and the angle between the field and the line of sight, and for changes of the field associated with the Ca ii-K umbral flashes discovered by Beckers and Tallant (1969). The power spectra show no significant peaks, conflicting with the results of Mogilevskii et al. (1972) who reported oscillations in the longitudinal component of the field strength with periods of 56, 90, and 150 s. Changes in the field were not observed to be correlated with the occurrence of umbral flashes. These results place restrictions on magnetic modes of energy transport between the photospheric layers and the chromospheric layers where the umbral flashes are observed.
Similar content being viewed by others
References
Beckers, J. M.: 1969, in D. G. Wentzel and D. A. Tidman (eds.), Plasma Instabilities in Astrophysics, Gordon and Breach, N.Y., p. 139.
Beckers, J. M. and Schröter, E. H.: 1968, Solar Phys. 4, 142.
Beckers, J. M. and Schröter, E. H.: 1969, Solar Phys. 7, 22.
Beckers, J. M. and Schultz, R. B.: 1972, Solar Phys. 27, 61.
Beckers, J. M. and Tallant, P. E.: 1969, Solar Phys. 7, 351.
Blackman, R. B. and Tukey, J. W.: 1958, The Measurement of Power Spectra, Dover Publ., N.Y., N.Y.
Brault, J. W. and White, O. R.: 1971, Astron. Astrophys. 13, 169.
Mogilevskii, E. I., Demkina, L. B., Ioshpa, B. A., and Obridko, V. N.: 1968, in K. O. Kiepenheuer (ed.), ‘Structure and Development in Solar Active Regions’, IAU Symp. 35, 215.
Mogilevskii, E. I., Obridko, V. N., and Shelting, B. D.: 1972, Astron. Tsirk. SSR 669, 1.
Mogilevskii, E. I., Obridko, V. N., and Shelting, B. D.: 1973, Izv. VUZ, Radio fiz. 16, 1357.
Moore, R. L.: 1973, Solar Phys. 30, 403.
Nakagawa, Y., Priest, E. R., and Wellck, R. E.: 1973, Astrophys. J. 184, 931.
Severny, A. B.: 1959, Soviet Astron. 3, 214.
Unno, W.: 1956, Publ. Astron. Soc. Japan 8, 108.
Zirin, H. and Stein, A.: 1972, Astrophys. J. 178, L85.
Author information
Authors and Affiliations
Additional information
The National Center for Atmospheric Research is sponsored by the National Science Foundation.
Rights and permissions
About this article
Cite this article
Schultz, R.B., White, O.R. Temporal variations of the magnetic field in sunspots. Sol Phys 35, 309–316 (1974). https://doi.org/10.1007/BF00151951
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00151951