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Ionization equilibrium in soft X-ray-emitting solar flares

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Abstract

Studies of the flare-produced line feature at 1.9 Å due to highly ionized iron show that it is emitted in conditions closely approximating steady-state ionization equilibrium. Calculations of the line flux per unit emission measure from time-dependent and steady-state ionization equilibria are compared with observed values during four flares in particular. Only for electron densities N e ⪞ 1010 cm-3 do the time-dependent equilibrium values give as good an approximation to the observed values as the steady-state equilibrium. This lower limit is compared with values of N e derived from analyses of the temperature decline in each of these events, and with estimates of N e given by other workers.

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Authors and Affiliations

  1. Laboratory for Solar Physics, NASA-Goddard Space Flight Center, 20771, Greenbelt, Md., U.S.A.

    K. J. H. Phillips, W. M. Neupert & R. J. Thomas

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  1. K. J. H. Phillips
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  2. W. M. Neupert
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  3. R. J. Thomas
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NAS/NRC Research Associate.

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Phillips, K.J.H., Neupert, W.M. & Thomas, R.J. Ionization equilibrium in soft X-ray-emitting solar flares. Sol Phys 36, 383–401 (1974). https://doi.org/10.1007/BF00151209

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  • DOI: https://doi.org/10.1007/BF00151209

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