Energy balance in cool quiescent prominences
Tóm tắt
The energy balance for cool quiescent prominences is examined using a 6000 km, 6000 K isothermal slab model prominence with a density gradient dictated by a modified Kippenhahn-Schlüter model. The model is irradiated from both sides by the coronal, chromospheric, and photospheric radiation fields. The radiative transfer problem is solved in detail for the Lyman continuum and Hα to determine the net radiative energy loss for hydrogen. An estimate of the energy loss for Ca ii H and K indicates that this source of energy loss is unimportant when compared with the hydrogen radiation. The radiative energy loss is easily balanced by the conductive energy gain from the corona. The only difficulty with our model is that the total hydrogen density must be of the order of 3 × 1012/ cm3 to match the n = 2 population density of 5 × 104/cm3 obtained from observation. To support a prominence of this density and a thickness of 6000 km against gravity requires magnetic fields of the order of 20 G which is much higher than the average magnetic field in quiescent prominences deduced from limb observations. Two possible explanations for this discrepancy are given.
Tài liệu tham khảo
Athay, R. G. and Thomas, R. N.: 1961, Physics of the Solar Chromosphere, Interscience Publishers, Inc., New York.
Giovanelli, R. G.: 1967, Australian J. Phys. 20, 81.
Hirayama, T.: 1964, Proc. Astron. Soc. Japan 16, 104.
Jefferies, J. T.: 1968, Spectral Line Formation, Blaisdell Publishing Co., Watham, Mass.
Jefferies, J. T. and Orrall, F. Q.: 1961, Astrophys. J. 134, 747.
Kawaguchi, I.: 1964, Proc. Astron. Soc. Japan 16, 86.
Kippenhahn, R. and Schlüter, A.: 1957, Z. Astrophys. 43, 36.
Linsky, J.: 1968, Calcium Line Formation in the Solar Chromosphere, SAO Special Report 274.
Oster, L. and Sofia, S.: 1966, Astrophys. J. 143, 944.
Poland, A., Skumanich, A., Athay, R. G., and Tandberg-Hanssen, E.: 1971 (to be published).
Sampson, D. and Golden, L.: 1970, Astrophys. J. 161, 321.
Spitzer, L., Jr.: 1962, Physics of Fully Ionized Gases (2nd ed.), Interscience Publishers, New York, p. 133.
Tandberg-Hanssen, E. and Anzer, U.: 1970, Solar Phys. 15, 158.
Yakovkin, N. A. and Zel'dina, M. Yu.: 1964, Soviet Astron. 8, 262.