Abstract
Extreme-ultraviolet (300–1350 Å) observations of nearly 500 solar flares from the satellites OSO 4 and OSO 6 have been compared with data in X-ray and radio wavelengths. It is found that EUV flares are closely associated with nonthermal X-ray and microwave bursts. The EUV maximum intensity generally precedes the maximum intensity in Hα or soft X-rays by up to several minutes. The EUV e-folding rise time and peak intensity both depend on the X-ray burst characteristics. Nonthermal X-ray flares tend to be accompanied by strong, rapidly rising EUV bursts, while thermal X-ray events are usually associated with weaker, more slowly rising EUV flares. These relations are consistent with a picture of the flare in which the EUV radiation is produced thermally in a region of high (chromospheric) density, which is being heated by collisional losses of the nonthermal electrons responsible for the impulsive X-ray and microwave burst.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Allen, J. W. and Dupree, A. K.: 1967, ‘Shock Tube Spectroscopy Laboratory Rpt. SR-24’, Harvard College Observatory.
Athay, R. G.: 1966, Astrophys. J. 145, 784.
Cox, D. P.: 1969, Ph.D. Thesis, University of California, San Diego.
Donnelly, R. F.: 1969, J. Geophys. Res. 74, 1873.
Donnelly, R. F.: 1970, ESSA Tech. Rpt. ERL 169-SDL 14.
Dupree, A. K.: 1968, Ph.D. Thesis, Harvard University.
Frost, K. J.: 1969, Astrophys. J. 158, L159.
Huber, M. C. E., Dupree, A. K., Goldberg, L., Noyes, R. W., Parkinson, W. H., Reeves, E. M., and Withbroe, G. L.: 1972, in preparation.
Kane, S. R.: 1969, Astrophys. J. 157, L139.
Kane, S. R. and Anderson, K. A.: 1970, Astrophys. J. 162, 1003.
Kane, S. R. and Donnelly, R. F.: 1971, Astrophys. J. 164, 151.
Kundu, M. R.: 1965, Solar Radio Astronomy, Wiley-Interscience, New York.
McIntosh, P. S.: 1970, (private communication).
Noyes, R. W., Withbroe, G. L., and Kirshner, R. P.: 1970, Solar Phys. 11, 388.
Parks, G. K. and Winckler, J. R.: 1971, Solar Phys. 16, 186.
Smerd, S. F.: 1969, Ann. IGY 34, 339.
Thomas, R. J.: 1970, Ph.D. Thesis, University of Michigan.
Thomas, R. J. and Teske, R. G.: 1971, Solar Phys. 16, 431.
Wood, A. T., Jr. and Dupree, A. K.: 1968, unpublished research, Harvard University.
Wood, A. T., Jr., Noyes, R. W., Dupree, A. K., Huber, M. C. E., Parkinson, W. H., Reeves, E. M., and Withbroe, G. L.: 1971, Solar Phys., this issue, p. 169.
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
Wood, A.T., Noyes, R.W. Solar flares in the extreme ultraviolet. Sol Phys 24, 180–196 (1972). https://doi.org/10.1007/BF00231095
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00231095