Five minute microwave solar oscillations

Abstract

Oscillations with a period of 5.6 min were observed on 10 July, 1978 while tracking at 22 GHz the active region McMath 15403. The oscillations were strong, clearly defined, had no damping, and lasted for about two hours. The rarity of the phenomenon is indicated by the fact that it occurred only once in more than 250 hr of solar observations. The possibility that these oscillations are due to a standing Alfv6n wave driven by the photospheric velocity field is discussed.

Coronal Loop Oscillations Observed with theTransition Region and Coronal Explorer

“…The fast kink mode was previously proposed to explain coronal oscillations in optical wavelengths (Roberts et al 1984), e.g., to explain the periods (q \ 43, 80, and 300 s) of coronal oscillations observed by Koutchmy, Zhugzhda, & Locans (1983), the 5.6 minute oscillation of radio sources observed by Strauss, Kaufmann, & Opher (1980), and oscillations in prominence Ðne structure (Joarder, Nakariakov, & Roberts 1997). The derived coronal magnetic Ðelds in those two cases were B \ 15 and B \ 44 G (Roberts et al 1984).…”

“…b Method : I \ Images (1D \ one-dimensional scans, 2D \ two-dimensional images), T \ time series analysis c Physical interpretation : MHD \ MHD wave modes (s \ sausage mode, k \ kink mode, sl \ slow mode, p \ propagating waves), NLC \ nonlinear limit cycle, PPO \ photospheric (5 minute) p-mode oscillations Alfve n REFERENCES.È(1) Parks & Winckler 1969 ;(2) Lipa 1978 ; (3) Takakura et al 1983 ;(4) Kiplinger et al 1983 ;(5) Desai et al 1987 ;(6) Harrison 1987 ;(7) Thomas, Neupert, & Thompson 1987 ;(8) Svestka 1994 ;(9) McKenzie 1997 ;(10) McKenzie & Mullan 1997 ;(11) Antonucci, Gabriel, & Patchett 1984 ;(12) DeForest & Gurman 1998 ;(13) this work ; (14) Koutchmy et al 1983 ;(15) Pasacho † & Landman 1984 ;(16) Pasacho † & Ladd 1987 ;(17) Jain & Tripathy 1998 ;(18) Simon & Shimabukuro 1971 ;(19) Bocchia & Puomeyrol 1974 ;(20) Strauss et al 1980 ;(21) Costa & Kaufmann 1986 ;(22) Janssens & White 1969 ;(23) Kaufmann 1972 ;(24) Zodi, Kaufmann, & Zirin 1984 ;(25) Correia & Kaufmann 1987 ;(26) Kattenberg & Kuperus 1983 ;(27) Fu et al 1990 ;(28) Qin & Guang-Li 1994 ;(29) Qin, Li, & Fu 1996 ;(30) Baranov & Tsvetkov 1994 ;(31)…”

Solar radio pulsating structures during September 9, 2001 at meter wavelength

“…Such a kind of events has been detected in stellar flares too (Bastian 1990;Mathioudakis et al 2003;Mitra-Kraev et al 2005). Most of the pulsations that had been observed are related to flares, although events with no apparent connection with such an activity have been reported too (Gaizauskas and Tapping 1980;Strauss et al 1980).…”

Diagnostics of Coronal Magnetic Field in Terms of Radio Burst and Fine Structures

“…For 1-minute pulsations, according to Aschwanden et al (1999), for the observed period about 60 s, assuming second harmonic emission, n=2.8 × 10 10 cm −3 and L=0.94 × 10 10 cm, we get B=170 G. For 6-minute pulsations, L= 5.0 × 10 10 cm, according to Strauss, Kaufmann, and Opher (1980), we get the Alfvén speed V A =2550km/s. At the height of 3 GHz emission, the electron density n=1.3 × 10 9 cm −3 , so the magnetic field B= 50 gauss; for the height of 17 GHz emission, n = 1.0 × 10 11 cm −3 , we get B= 380 Gauss.…”