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Energy Dissipation Mechanisms in Flare Stars

Published online by Cambridge University Press:  04 August 2017

D. J. Mullan
D. J. Mullan*
Affiliation:
Bartol Research Foundation of The Franklin Institute, University of Delaware Newark, Delaware 19711 U.S.A.

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Flare stars derive their name from intermittent increases in luminosity which have certain characteristics reminiscent of solar flares (e.g. enhanced strengths of emission lines in the stellar spectrum during the outbursts). When a flare star is observed in a filter which transmits, say, the violet part of the visible spectrum, the increase in luminosity during a flare may range from noise level up to perhaps 100 times the quiescent brightness. During a flare, certain spectral features of the quiescent star (e.g. molecular bands) remain visible, indicating that the flare occupies only a fraction of the visible disk. Thus, analagous to a solar flare, a stellar flare is confined to a single active region. However the total power is large enough to affect the integrated light from the stellar disk. In contrast, the largest solar flare (Etot ≈ 1032 ergs) has a rate of energy release (L ≈ 1029 erg/sec) which is so small that a distant observer would record such a flare as a luminosity increase of less than 10−4Lsun. However, even apart from the flares themselves, it has become apparent in recent years that flare stars in their “quiescent state” provide some extreme contrasts with the sun.

Type
Session IV
Information
Symposium - International Astronomical Union , Volume 107: Unstable Current Systems and Plasma Instabilities , 1985 , pp. 245 - 262
Copyright
Copyright © Reidel 1985 

References

Abrami, A.: 1970, Solar Phys. 11, p. 104.CrossRefGoogle Scholar
Cram, L.E.: 1982, Ap. J. 253, p. 768.CrossRefGoogle Scholar
Cram, L.E. and Mullan, D.J.: 1979, Ap. J. 234, p. 579.CrossRefGoogle Scholar
Cram, L.E. and Woods, D.T.: 1982, Ap. J. 257, p. 269.CrossRefGoogle Scholar
De Groot, T.: 1970, Solar Phys. 14, p. 176.CrossRefGoogle Scholar
Fowler, L. et al.: 1983, Solar Phys. 84, p. 33.CrossRefGoogle Scholar
Gaizauskas, V. and Tapping, K.F.: 1980, Ap. J. 241, p. 804.CrossRefGoogle Scholar
Gershberg, R.E.: 1983, in Rodono, and Byrne, (1983).Google Scholar
Giampapa, M.: 1983, in Proc. IAU Symp. No. 102, p. 187.CrossRefGoogle Scholar
Giampapa, , et al.: 1982, Ap. J. (Letters) 252, p. L39.CrossRefGoogle Scholar
Gibson, D.M.: 1983, in Rodono, and Byrne, (1983).Google Scholar
Haisch, B.M.: 1983, in Rodono, and Byrne, P. (1983).Google Scholar
Haisch, B.M. et al: 1983, Ap. J. 267, p. 280.CrossRefGoogle Scholar
Hoxie, D.: 1973, Astron. Astrophys. 26, p. 437.Google Scholar
Ionson, J.A.: 1983, Ap. J. (In press).Google Scholar
Kelch, W. et al.: 1979, Ap. J. 229, p. 700.CrossRefGoogle Scholar
Kodaira, K.: 1983, in Rodono, and Byrne, (1983).Google Scholar
Kunkel, W.E.: 1975, in “Variable Stars and Stellar Evolution”, ed. Sherwood, V. and Plaut, L. (Dordrecht: Reidel), p. 47.Google Scholar
Lacy, C.H.: 1976, Ap. J. Suppl. 30, p. 85.CrossRefGoogle Scholar
Leighton, R.B.: 1963, Ann. Rev. Astron. Ap. 1, p. 19.CrossRefGoogle Scholar
Linsky, J.L. et al.: 1982, Ap. J. 260, p. 670.CrossRefGoogle Scholar
Linsky, J.L. et al.: 1982, Ap. J. (Letters) 263, p. L79.Google Scholar
Livshits, M.A. et al.: 1981, Solar Phys. 73, p. 269.CrossRefGoogle Scholar
Maxwell, A. and Fitzwilliam, J.: 1973, Astrophys. Letters 13, p. 237.Google Scholar
McLean, D.J. et al.: 1971, Nature 234, p. 140.CrossRefGoogle Scholar
Moffett, T.J.: 1974, Ap. J. Suppl. 29, p. 1.CrossRefGoogle Scholar
Moore, R.L. and Datlowe, D.: 1975, Solar Phys. 43, p. 189.CrossRefGoogle Scholar
Mould, J. and Hyland, A.: 1976, Ap. J. 208, p. 399.CrossRefGoogle Scholar
Mullan, D.J.: 1971, Monthly Not. Roy. Astron. Soc. 154, p. 467.CrossRefGoogle Scholar
Mullan, D.J.: 1974a, Ap. J. 187, p. 612.CrossRefGoogle Scholar
Mullan, D.J.: 1974b, Ap. J. 192, p. 149.CrossRefGoogle Scholar
Mullan, D.J.: 1975a, Astron. Astrophys. 40, p. 41.Google Scholar
Mullan, D.J.: 1975b, Ap. J. 200, p. 641.CrossRefGoogle Scholar
Mullan, D.J.: 1976, Irish Astron. J. 12, p. 161; ibid. 12, p. 277.Google Scholar
Mullan, D.J.: 1979, Ap. J. 231, p. 152.CrossRefGoogle Scholar
Mullan, D.J.: 1981, Solar Phys. 70, p. 381.CrossRefGoogle Scholar
Mullan, D. J. and Bell, R. A.: 1976, Ap. J. 204, p. 818.CrossRefGoogle Scholar
Oskanian, V.S. and Terebizh, V.J.: 1971, Astrofizika 7, p. 83.Google Scholar
Pettersen, B.: 1980, Astron. Astrophys. 82, p. 53.Google Scholar
Pettersen, B.: 1983, in Rodono, and Byrne, (1983).Google Scholar
Rodono, M.: 1974, Astron. Astrophys. 32, p. 337.Google Scholar
Rodono, M. and Byrne, P.B. (editors): 1983, “Activity in Red Dwarf Stars”, Proc. IAU Colloq. No. 71. (Dordrecht: Reidel).Google Scholar
Rosenberg, P.: 1970, Astron. Astrophys. 9, p. 159.Google Scholar
Rosner, R. et al.: 1978, Ap. J. 222, p. 317.CrossRefGoogle Scholar
Rosner, R. et al.: 1981, Ap. J. (Letters) 249, p. L5.CrossRefGoogle Scholar
Spangler, S. et al.: 1974, Ap. J. (Letters) 194, p. L43.CrossRefGoogle Scholar
Spicer, D.S. and Brown, J.C.: 1981, in The Sun as a Star, ed. Jordan, S. (Washington: NASA SP–450), p. 413.Google Scholar
Stern, R.A. et al.: 1983, Ap. J. (Letters) 264, p. L55.CrossRefGoogle Scholar
Uchida, Y.: 1968, Solar Phys. 4, p. 30.CrossRefGoogle Scholar
Vogt, S.S.: 1983, in Rodono and Byrne (1983).Google Scholar
Willson, R.W.: 1980, Science 211, p. 700.CrossRefGoogle Scholar
Withbroe, G. and Noyes, R.W.: 1977, Ann. Rev. Astron. Ap. 15, p. 363.CrossRefGoogle Scholar