Abstract
The Hα line profile in a flare atmospheric model superposed by a spatially correlated velocity field is studied in detail in this paper. The computations are carried out with the assumption that the velocity field is represented by a Kubo-Anderson process. It is found that the shape and the intensity of the Hα line profile depend greatly on the parameters of the velocity field. The variation of the profile and its relative deviation with respect to different correlation lengths is more complex than in the case of absorption lines. It is also shown that such a profile cannot be matched by those produced in the usually-used micro- and macro-turbulent approaches, especially for the velocity field with an intermediate correlation length. The results imply that the flare atmosphere should be highly turbulent in order to explain the observed Hα line profile with only weak central reversal in the flare spectra. Particularly, the effects of meso-turbulent fields should be taken into account in order to improve the spectral diagnostics and modelling of the flare atmosphere.
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Auvergne, M., Frisch, H., Frisch, U., Froeschlé, Ch., and Pouquet, A.: 1973,Astron. Astrophys. 29, 93.
Carlsson, M. and Scharmer, G. B.: 1985, in B. W. Lites (ed.),Chromospheric Diagnostics and Modelling, Solar Observatory, Sunspot, p. 137.
Ding, M. D.: 1992, Ph.D. thesis, Nanjing University.
Ding, M. D. and Fang, C.: 1989,Astron. Astrophys. 225, 204.
Ding, M. D. and Fang, C.: 1990,Publ. Purple Mt. Obs. 9, 133.
Fang, C., Hiei, E., Yin, S. Y., and Gan, W. Q.: 1992,Publ. Astron. Soc. Japan 44, 63.
Frisch, H.: 1975,Astron. Astrophys. 40, 267.
Frisch, H. and Frisch, U.: 1976,Monthly Notices Roy. Astron. Soc. 175, 157.
Froeschlé, Ch. and Frisch, H.: 1980,Astron. Astrophys. 91, 202.
Gail, H.-P. and Sedlmayr, E.: 1974,Astron. Astrophys. 36, 17.
Gail, H.-P., Sedlmayr, E., and Traving, G.: 1975,Astron. Astrophys. 44, 421.
Gail, H.-P., Sedlmayr, E., and Traving, G.: 1976,Astron. Astrophys. 46, 441.
Gail, H.-P., Sedlmayr, E., and Traving, G.: 1980,J. Quant. Spectr. Rad. Transfer 23, 267.
Gail, H.-P., Hundt, F., Kegel, W. H., Schmid-Burgk, J., and Traving, G.: 1974,Astron. Astrophys. 32, 65.
Gan, W. Q. and Fang, C.: 1987,Solar Phys. 107, 311.
Gouttebroze, P., Lemaire, P., Vial, J. C., and Artzner, G.: 1978,Astrophys. J. 225, 655.
Hundt, E.: 1973,Astron. Astrophys. 29, 17.
Loucif, M. L. and Magnan, C.: 1982,Astron. Astrophys. 112, 287.
Machado, M. E., Avrett, E. H., Vernazza, J. E., and Noyes, R. W.: 1980,Astrophys. J. 242, 336.
Magnan, C.: 1976,J. Quant. Spectr. Rad. Transfer 16, 281.
Magnan, C.: 1985,Astron. Astrophys. 144, 186.
Mihalas, D.: 1978,Stellar Atmospheres, 2nd ed., Freeman, San Francisco.
Schmid-Burgk, J.: 1974,Astron. Astrophys. 32, 73.
Traving, G.: 1964,Z. Astrophys. 60, 167.
Traving, G.: 1975, in B. Baschek, W. H. Kegel, and G. Traving (eds.),Problems in Stellar Atmospheres and Envelopes, Springer-Verlag, Berlin, p. 325.
Traving, G.: 1980, in D. F. Gray and J. L. Linsky (eds.),Stellar Turbulence, Springer-Verlag, Berlin, p. 172.
Vernazza, J. E., Avrett, E. H., and Loeser, R.: 1981,Astrophys. J. Suppl. 45, 635.
Worrall, G. and Wilson, A. M.: 1972,Nature 236, 15.
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Ding, M.D., Fang, C. Hα emission line profiles of solar flares with turbulent velocity fields. Sol Phys 147, 305–321 (1993). https://doi.org/10.1007/BF00690720
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DOI: https://doi.org/10.1007/BF00690720