Solar Radio Physics
   Institute in General
   Events / Jobs
   Public Relations
   Research Groups
   Internal Pages
Search Telephone list Feedback Impressum Links
last change 2007 March 23, H. Ínel
Solar Radio Physics - Research Branch I de
[ AIP Home ] [ Radio Physics Home ]

Radio Observatory - Introduction

Why Studying Coronal Plasma Processes by Radio Astronomy?

The corona - here an actual view by the SOHO satellite of ESA and NASA - is the outer part of the solar atmosphere and the source of the solar wind. It represents an inhomogeneous, hot, dilute, and fully ionized plasma. Its spatial structures are governed by the magnetic field. Important effects of stellar activity can be observed with unprecedended accuracy, such as coronal mass ejections (CMEs), flares and prominence eruptions, shock wave formation, and last but not least particle acceleration. Despite being of general astrophysical relevance these processes are not yet fully understood until now.

Plasma processes associated with solar activity take place on small spatial and temporal scales. If these processes are accompanied by electron acceleration (up to a few MeV) they can emit radio radiation. Consequently, such "nonthermal" electrons can be traced by radio methods. Solar radio observations are in some respect different from general radio astronomy. Signals are not extremely weak but highly varying in time and space. The background (the solar disc and its surroundings) is spatially extended and varying, too.

Various plasma processes (particle acceleration, storage, and escape; excitation of various wave modes) manifest themselves as solar radio burst patterns in dynamic spectral diagrams. The radio spectra can be used as one starting point of the theoretical study of basic plasma processes in the corona. Further, due to good spectral coverage, high time resolution, and high sensitivity, the AIP spectral observations yield an excellent guide and time line for assembling associated data sets from complementary ground- and space-based instrumentation.

Spectral diagrams are used to represent the data (x-axis represents time, y-axis represents the log. frequency in reversed direction, whereas the log. flux density is colour coded).