Abstract
Soft-X-ray and extreme ultraviolet spectroheliographs carried by the OSO-7 (Orbiting Solar Observatory) have been used to record the development of XUV emission associated with a flare of importance 1b on August 2, 1972. Spatial resolution was 20″ and spectral resolution was adequate to select emission lines originating within well-defined ranges of electron temperature between 5 × 104 and 30 × 106K. The data show that heating only the pre-existing coronal material adjacent to the flare site cannot account for the soft X-ray emission measure observed during the event. The flare emission originating at T e ⩽ 2.3 × 106K exhibits an impulsive component coincident with an impulsive microwave event. This radiation appears to coincide spatially with Hα radiation emitted at that time and is centered on the neutral line separating magnetic fields of opposite polarity. One soft X-ray-emitting feature, estimated to have an initial electron temperature of 2–10 × 106K, forms during the impulsive phase immediately over the Hα flare. A second, arch-like feature observed at wavelengths near 1.9 Å and estimated to have T e≅30 × 106K is located approximately 35000 km above the Hα event. Both regions have lengths of about 27000 km but transverse dimensions small compared to the spatial resolution of the spectroheliograph, i.e., less than 14000 km. The region with highest electron temperature exhibits the greatest stability in position. This region cools to approximately 10 × 106K in 6 to 12 min which is compatible with cooling by conduction to the chromosphere. The best association with a dark surge is found in an emission line of Fe xiv.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Behring, W. E., Cohen, L., and Feldman, U.: 1972, Astrophys. J. 175, 493.
Beigman, I. L., Grineva, Yu. I., Mandel'stam, S. L., Vainstein, L. A., and Zhitnik, I. A.: 1969, Solar Phys. 9, 160.
Blaha, M.: 1971, Solar Phys. 17, 99.
Culhane, J. L., Vesecky, J. F., and Phillips, K. J. H.: 1970, Solar Phys. 15, 394.
Datlowe, D.: 1972, private communication.
de Boer, K. S., Olthof, H., and Pottasch, S. R.: 1972, Astron. Astrophys. 16, 417.
de Jager, C. and Kundu, M. R.: 1963, Space Res. 3, 836.
Donnelly, R. F.: 1969, J. Geophys. Res. 74, 1873.
Gold, T.: 1968, Mass Motions in Solar Flares and Related Phenomena, J. Wiley and Sons, N.Y., p. 205.
Hall, L. A.: 1971, Solar Phys. 21, 167.
Hall, L. A. and Hinteregger, H. E.: 1969, in C. de Jager and Z. Švestka (eds.), ‘Solar Flares and Space Research’, COSPAR Symp., 81.
Hall, L. A. and Hinteregger, H. E.: 1970, J. Geophys. Res. 75, 6959.
Jordan, C.: 1969, Monthly Notices Roy. Astron. Soc. 142, 501.
Kane, S. R. and Anderson, K. A.: 1970, Astrophys. J. 162, 1003.
Kane, S. R. and Donnelly, R. F.: 1971, Astrophys. J. 164, 151.
Kane, S. R. and Lin, R. P.: 1972, Solar Phys. 23, 457.
Livingston, W.: 1972, private communication.
Mangus, J. D.: 1970, Appl. Opt. 9, 1019.
Martin, S.: 1972, private communication.
Mewe, R.: 1972, Solar Phys. 22, 459.
Neupert, W. M.: 1968, Astrophys. J. 153, L59.
Neupert, W. M.: 1969, Ann. Rev. Astron. Astrophys. 7, 121.
Neupert, W. M. and Swartz, M.: 1970, Astrophys. J. 160, L189.
Neupert, W. M., White, W. A., Gates, W. J., Swartz, M., and Young, R. M.: 1969, in C. de Jager and Z. Švestka (eds.), ‘Solar Flares and Space Research’, COSPAR Symp., 95.
Neupert, W. M, Kastner, S. O., and Swartz, M.: 1973, submitted for publication.
Purcell, J. D. and Widing, K. G.: 1972, Astrophys. J. 176, 239.
Ross, P. A.: 1926, Phys. Rev. 28, 425.
Saba, J.: 1972, Masters Thesis, University of Maryland.
Strauss, F. M. and Papagiannis, M. D.: 1971, Astrophys. J. 164, 369.
Sturrock, P. A.: 1968, in K. O. Kiepenheuer (ed.), ‘Structure and Development of Solar Active Regions’, IAU Symp. 35, 471.
Sturrock, P. A.: 1972, ‘Mass Motion in Solar Flares’, SUIPR Report No. 498.
Sturrock, P. A. and Smith, S. M.: 1968, Solar Phys. 5, 87.
Sweet, P. A.: 1958, in B. Lehnert (ed.), Electromagnetic Phenomena in Cosmical Physics, Cambridge University Press, p. 123.
Takakura, T.: 1971, Solar Phys. 19, 186.
Takakura, T. and Kai, K.: 1966, Publ. Astron. Soc. Japan 18, 57.
Takakura, T., Ohki, K., Shibuya, N., Fujii, M., Matsuoka, M., Miyamoto, S., Nishimura, J., Oda, M., Ogawara, Y., and Ota, S.: 1971, Solar Phys. 16, 454.
Tanaka, K. and Nakagawa, Y.: 1973, to be published.
Tousey, R.: 1971, Phil. Trans. Roy. Soc. London A270, 59.
Trubnikov, B. A.: 1965, Rev. Plasma Phys. 1, 105.
Vaiana, G. S. and Giacconi, R.: 1969, in D. G. Wentzel and D. A. Tidman (eds.), Plasma Instabilities in Astrophysics, Gordon and Breach, N.Y., p. 91.
Vaiana, G. S., Reidy, W. P., Zehnpfennig, T., Van Speybroeck, L., and Giacconi, R.: 1968, Science 161, 564.
Vorpahl, J. and Zirin, H.: 1970, Solar Phys. 11, 285.
Wolter, H.: 1952, Ann. Phys. (Leipzig) 10, 94.
Wood, Jr., A. T., Noyes, R. W., and Reeves, E. M.: 1972, in P. S. McIntosh and M. Dryer (eds.), Solar Activity Observations and Predictions, MIT Press, Cambridge, p. 117.
Zhitnik, I. A., Krutov, V. V., Maljavkin, L. P., Mandel'stam, S. L., and Cheremukhin, G. S.: 1967, Space Res. 7, 1263.
Zirin, H. and Tanaka, K.: 1973, Solar Phys. 32, 173.
Zirin, H., Ingham, W., Hudson, H., and McKenzie, D.: 1969, Solar Phys. 9, 269.
Zirin, H., Pruss, G., and Vorpahl, J.: 1971, Solar Phys. 19, 463.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Neupert, W.M., Thomas, R.J. & Chapman, R.D. Spatial distribution of soft X-ray and EUV emission associated with a chromospheric flare of importance 1B on August 2, 1972. Sol Phys 34, 349–375 (1974). https://doi.org/10.1007/BF00153673
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00153673