Abstract
We consider the modulation of nonthermal gyrosynchrotron emission from solar flares by the ballooning and radial oscillations of coronal loops. The damping mechanisms for fast magnetoacoustic modes are analyzed. We suggest a method for diagnosing the plasma of flare loops that allows their main parameters to be estimated from peculiarities of the microwave pulsations. Based on observational data obtained with the Nobeyama Radioheliograph (17 GHz) and using a technique developed for the event of May 8, 1998, we determined the particle density n≈3.7×1010 cm−3, the temperature T≈4×107 K, and the magnetic field strength B≈220 G in the region of flare energy release. A wavelet analysis for the solar flare of August 28, 1999, has revealed two main types of microwave oscillations with periods P 1≈7, 14 s and P 2≈2.4 s, which we attribute to the ballooning and radial oscillations of compact and extended flare loops, respectively. An analysis of the time profile for microwave emission shows evidence of coronal loop interaction. We determined flare plasma parameters for the compact (T≈5.3×107 K, n≈4.8≈1010 cm−3, B≈280 G) and extended (T≈2.1≈107 K, n≈1.2≈1010 cm−3, B≈160 G) loops. The results of the soft X-ray observations are consistent with the adopted model.
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References
A. Asai, M. Shimojo, H. Isobe, et al., Astrophys. J. 562, L103 (2001).
M. J. Aschwanden, Solar Phys. 111, 113 (1987).
M. J. Aschwanden, NATO Advanced Research Workshops, NATO Sci. Ser. II, Ed. by R. von Fay Siebenburgen, K. Petrovy, B. Roberts, and M. J. Aschwanden (Kluwer Acad., Dordrecht, 2003), p. 22.
M. J. Ashwanden, L. Fletcher, C. J. Schrijver, et al., Astrophys. J. 520, 880 (1999).
T. S. Bastian, in Proceedings of the Nobeyama Symp. NRO No. 479, Ed. by T. Bastian, N. Gopalswamy, and K. Shibasaki (Nobeyama Radio Obs., Nagano, 1998), p. 211.
S. I. Braginskii, Vopr. Teor. Plazmy 1, 183 (1963).
O. S. Burdo, O. K. Cheremnykh, and O. P. Verkhoglyadova, Izv. Ross. Akad. Nauk, Ser. Fiz. 64, 1896 (2000).
G. A. Doschek, in Proceedings of the Kofu Symp. NRO No. 360, Ed. by S. Enome and T. Hirayama (Nobeyama Radio Obs., Nagano, 1994), p. 173.
G. A. Dulk and K. A. Marsh, Astrophys. J. 259, 350 (1982).
G. D. Fleishman and V. F. Melnikov, Astrophys. J. 587, 823 (2003).
Yu. G. Kopylova and A. V. Stepanov, Izv. Glavn. Astron. Obs. 216, 555 (2002).
Yu. G. Kopylova, A. V. Stepanov, and Yu. T. Tsap, Pis'ma Astron. Zh. 28, 870 (2002).
J. Lee, D. E. Gary, J. Qiu, et al., Astrophys. J. 572, 609 (2002).
M. Mathioudacis, J. H. Seiradakis, D. R. Williams, et al., Astron. Astrophys. 403, 1101 (2003).
B. I. Meerson, P. V. Sasorov, and A. V. Stepanov, Solar Phys. 58, 165 (1978).
F. Meyer, H. U. Schmidt, and N. O. Weiss, Mon. Not. R. Astron. Soc. 179, 741 (1977).
A. B. Mikhailovskii, Theory of Plasma Instabilities (Consultants Bureau, New York, 1974; Atomizdat, Moscow, 1971), Vol. 2.
H. Nakajima, K. Shibasaki, T. Yokoyama, et al., Nobeyama Radioheliograph Catalog of Events No. 3 (Nobeyama Radio Obs., Nagano, 2002).
V. M. Nakariakov, V. F. Melnikov, and V. E. Reznikova, Astron. Astrophys. 412, L7 (2003).
V. M. Nakariakov and L. Ofman, Astron. Astrophys. 372, L53 (2001).
V. Petrosian, T. Q. Donaghy, and J. M. McTiernan, Astrophys. J. 569, 459 (2002).
E. R. Priest, Solar Magnetohydrodynamics (Reidel, Dordrecht, 1982; Mir, Moscow, 1985).
L. A. Pustil'nik, Astron. Zh. 50, 1211 (1973) [Sov. Astron. 17, 763 (1973)].
Z. Qin, C. Li, Q. Fu, and Z. Gao, Solar Phys. 163, 383 (1996).
B. Roberts, Solar System Magnetic Fields, Ed. by E. R. Priest (Nobeyama Radio Obs., Nagano, 1986), p. 37.
H. Rosenberg, Astron. Astrophys. 9, 159 (1970).
J. Sato, M. Sawa, S. Masuda, et al., The Yohkoh HXT Image Catalogue. October 1991–August 1998 (Nobeyama Radio Obs., Nagano, 1998).
K. Shibasaki, in Proceedings of the Nobeyama Symp. NRO No. 479, Ed. by T. Bastian, N. Gopalswamy, and K. Shibasaki (Nobeyama Radio Obs., Nagano, 1998), p. 419.
K. Shibasaki, Astrophys. J. 557, 326 (2001).
A. V. Stepanov and Y. T. Tsap, Solar Phys. 211, 135 (2002).
R. J. Thomas, R. Starr, and C. J. Crannell, Solar Phys. 95, 323 (1985).
Y. T. Tsap, Solar Phys. 194, 131 (2000).
Yu. T. Tsap and Yu. G. Kopylova, in Proceedings of the International Seminar on Solar and Stellar Physics, Ed. by B. B. Mikhalyaev, V. V. Mustsevoi, and A. A. Solov'ev(Kalmyk. Gos. Univ., Elista, 2003), p. 123.
V. V. Vityazev, Wavelet Analysis of Time Series (St. Peterburg. Gos. Univ., 2001).
T. F. Volkov, Vopr. Teor. Plazmy 4, 3 (1964).
T. Yokoyama, H. Nakajima, K. Shibasaki, et al., Astrophys. J. 576, L87 (2002).
V. V. Zaitsev and A. V. Stepanov, Pis'ma Astron. Zh. 8, 248 (1982) [Sov. Astron. Lett. 8, 132 (1982)].
V. V. Zaitsev and A. V. Stepanov, Pis'ma Astron. Zh. 15, 154 (1989) [Sov. Astron. Lett. 15, 66 (1989)].
V. V. Zaitsev and A. V. Stepanov, Issled. Geomagn. Aéron. Fiz. Solntsa 37, 3 (1975).
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Translated from Pis'ma v Astronomicheski\(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l} \) Zhurnal, Vol. 30, No. 7, 2004, pp. 530–539.
Original Russian Text Copyright © 2004 by Stepanov, Kopylova, Tsap, Shibasaki, Melnikov, Goldvarg.
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Stepanov, A.V., Kopylova, Y.G., Tsap, Y.T. et al. Pulsations of microwave emission and flare plasma diagnostics. Astron. Lett. 30, 480–488 (2004). https://doi.org/10.1134/1.1774400
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DOI: https://doi.org/10.1134/1.1774400