The existence of quasi-periodic oscillations with periods from a minute up to some hours in the solar radio emission at ? = 3 cm

Kobrin, M. M.; Pakhomov, V. V.; Prokof'eva, N. A.

doi:10.1007/bf00206196

Cited by 13 publications

(4 citation statements)

References 9 publications

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“…Oscillatory phenomena have been observed in different solar structures (sunspots, pores, coronal loops, faculae) by ground-based and cosmic instruments for several tens of years (Kobrin et al 1976;Ofman 2000;Loukitcheva et al 2006;Dorotovič et al 2008;Foullon et al 2004Foullon et al , 2009Yuan et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Long quasi-periodic oscillations of sunspots and nearby magnetic structures

Smirnova

Riehokainen

Соловьев

et al. 2013

A&A

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Aims. Simultaneous study of long quasi-periodic oscillations in sunspots (using line-of-sight magnetic field data) and nearby magnetic structures located above them (using radio emission data at 37 GHz) was the basic aim of this work. Methods. Data from the ground-based radio-telescope (Metsähovi Radio Observatory, Aalto University, Finland) and the Helioseismic and Magnetic Imager instrument on-board the Solar Dynamics Observatory spacecraft were obtained and analyzed. We used the wavelet (Morlet) analysis and the fast Fourier transform (FFT) method to obtain the oscillation periods. Results. Long-period oscillations in intervals of 200-400 min were found both in radio and in magnetic field data. The interpretation of these oscillations and their propagation to higher levels of the solar atmosphere are discussed in the context of a "shallow sunspot" model.

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Section: Introductionmentioning

confidence: 99%

Long quasi-periodic oscillations of sunspots and nearby magnetic structures

Smirnova

Riehokainen

Соловьев

et al. 2013

A&A

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“…Unfortunately, no power spectral information is available, but Deubner [ 1972] has noted that there may be appreciable power at the long periods expected for the waves considered in this review. Radio observations [Kobrin et al, 1976] [Hollweg, 1968;Hollweg and Harrington, 1968;Woo et al, 1976b;Woo, 1978], and measurements of angular broadening provide information about Viine [Hollweg, 1968[Hollweg, , 1970bHollweg and Harrington, 1968;Woo et al, 1977;Woo, 1978]. Woo et al [1976a] have demonstrated the existence of large-scale density fluctuations at r • 45rs; they interpret the fluctuations in terms of 'turbulence,' but there is no reason why an interpretation in terms of waves of solar origin cannot be made.…”

Section: Observational Implicationsmentioning

confidence: 99%

Some physical processes in the solar wind

Hollweg¹

1978

Reviews of Geophysics

260

138

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The 'standard physics' of the solar wind is reviewed, and arguments that this standard physics is inadequate are summarized. A variety of suggestions for modifying the physics of the solar wind are then reviewed, with emphasis on effects of MHD waves of solar origin and collisionless or instability-limited electron heat conduction. The basic effects of the modified physics are demonstrated in a two-fluid model of the solar wind flow. The predictions of this model are carefully compared with observations, and the need for further observations is emphasized. The review concludes with suggestions for future theoretical efforts. THE STANDARD PHYSICSFor about a decade now it has become increasingly apparent that the 'standard physics' of the solar wind represents an inadequate description of the real solar wind and that additional and alternate processes must be at work. It is the purpose of this review to summarize some of the relevant processes and to construct a new model of the solar wind flow which incorporates their effects. The following physical considerations may be said to constitute the standard physics of the solar wind. 1. Mass is conserved without sources or sinks. In multifluid models of the solar wind, ionization and recombination are usually dropped, so that each species is then separately conserved without sources or sinks. But ionization and recombination can in fact be important for the minor ions low in the corona [e.g., Bame et al., 1974; Hundhausen et al., 1968; Joselyn, 1977] and for the solar wind/interstellar particle interaction far from the sun [e.g., Axford, 1972, 1973; Holzer, 1972, 1977a].2. The flow is accelerated by the algebraically summed thermal pressure gradients of all constituent species. In multifluid models of the solar wind the pressure gradient of each species contributes directly to its own acceleration but also indirectly to the acceleration of all other species via its contribution to the interplanetary electric field, which exists in virtue of the requirements of charge neutrality and charge conservation. The pressure is usually taken to be a scalar, but some kinetic or semikinetic models have been explored, for which the thermal pressure is anisotropic and therefore a tensor [e.g., ]. Although kinetic models may be vital for understanding microphysical processes such as wave-particle interactions, they are probably unnecessary for understanding the basic macrophysics of the solar wind [e.g., Leer and Holzer, 1972].The reasons for this are, first, that the electron anisotropy (at least as observed in the vicinity of 1 AU) is small and thus of no major consequence and, second, that the protons probably do not become strongly anisotropic until they are highly supersonic [Hundhausen, 1968;Hollweg, 1970a], in which case the thermal pressure is small in comparison with the inertia, and the anisotropy is again of no major consequence.3. The flow is decelerated by gravity. Generally, both the flow velocity v0 and the gravitational field g are taken to be in the radial direction....

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“…Attempts to observe related intensity variations at radio wavelengths haye produced contradictory results. Several authors have found various periodicities in the range 10-1000 s (e.g., Durasova et al, 1971;Simon and Shimabukuro, 1971;Lang, 1974a;Avery, 1976;Kobrin et al, 1976), while others report negative or inconclusive results (Shuter and McCutcheon, 1973;Sentman and Shawhan, 1974;Kundu and Alissandrakis, 1975;Zirin et al, 1978;Morita, 1979). In general the signal to noise ratio is so low that the oscillations appear only as peaks in the power spectra of long records of radio data, and their significance has often been questioned.…”

Section: Introductionmentioning

confidence: 99%

Five minute microwave solar oscillations

1980

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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.

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The existence of quasi-periodic oscillations with periods from a minute up to some hours in the solar radio emission at ? = 3 cm

Cited by 13 publications

References 9 publications

Long quasi-periodic oscillations of sunspots and nearby magnetic structures

Long quasi-periodic oscillations of sunspots and nearby magnetic structures

Some physical processes in the solar wind

Five minute microwave solar oscillations

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