Objective
MHD waves play an important role in the processes of the transfer, accumulation and release of energy in the solar atmosphere. More than that, an analysis of the resonance manifestation of such waves opens an important tool to study the plasma structures of the sun, even to measure the plasma parameters below the solar photosphere.
Observations of the radio emission gains a powerful tool to study many parameters of the plasma structures of the solar active regions, magnetic fields in the solar corona especially. The detection of the 3-minute and 5-minute oscillations in sunspot-associated sources generated by thermal cyclotron emission (Gelfreikh et al. 1999, Sol.Phys. 185/1) demonstrated exclusively high sensitivity of the method (amounting several Gauss in the field of 2000 G in the soar corona above a sunspot). Further development of the method made at Pulkovo Observatory using Nobeyama radio heliograph mapping the sun at the wavelength of 1.76cm has shown the presence of oscillations with other periods up to 2 hours and their harmonics. Also the presence the 3-minute oscillations above sunspot were detected in polarized radio emission (generated by thermal bremsstrahlung) without any manifestation in the channel of intensity.
The goal of the project is to use powers of the modern radio telescopes at microwaves to study all possible manifestation of periodic processes in magnetospheres of the solar active regions. Important point in usage radio observations is that many of them have the rich bank of data including results of daily tracking the sun for years. So, beside higher (as compared to optical methods) sensitivity they present the chance to study stability, variations in spectra, amplitudes, and connection with other types of solar activity without any specially organized programs. In some cases for use of radio telescopes with wider program range (such as VLA) special programs of the solar observations are to be organized.
The main participants of the program either have large instruments to study the radio oscillation in the local radio sources of the solar active regions (RATAN-600, SSRT, RT-22)
or have large experience in usage data with Nobeyama radio heliograph or VLA. Besides many participants of the project have great experience in modelling different radio components of the active regions and measuring such parameters of the solar atmosphere as magnetic fields, temperature, density, presence of non thermal particle and their spatial distribution as well.
The expected results of observational part of the program will lead to the basis for including the variation of the plasma parameters of the magnetospheres of the solar active regions due to MHD oscillations into the computer models of the radio emission. This could help to choose among the existing theories of oscillations as in sunspot resonance cavities and in coronal loops as well. Also the amplitude of the MHD oscillation will be found much more reliable. New approach to the problem may be found. Connection with the flare and other activity of the solar active region may be found too.
Call for proposal
Data not availableFunding Scheme
Data not availableCoordinator
45110 Ioannina
Greece