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Multi-frequency observations of radio enhanced temperature regions of the Sun

Published online by Cambridge University Press:  14 March 2005

A. Riehokainen
Affiliation:
Tuorla Observatory, Turku University, Finland email: alerie@utu.fi
A.G. Tlatov
Affiliation:
Kislovodsk Solar Station of the Pulkovo Observatory, Russia
S. Urpo
Affiliation:
Metsahovi Radio Observatory, Helsinki Univ. of Technology, Finland
E. Valtaoja
Affiliation:
Tuorla Observatory, Turku University, Finland email: alerie@utu.fi
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Abstract

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We compare the enhanced temperature regions (ETRs) in the millimeter radio emission of the Sun with other manifestation of solar activity during 10 days in 1997, 1998, 2000 and 2003. The radio observations at 37 GHz and 87 GHz were done with the Metsahovi Radio Telescope (Finland). We concentrate on the weak ETRs with no discernible connection to sunspots, and in some case compare their properties with those which do have a clear connection to sunspots. Extended observations at 37 GHz in July 2003 enable us to measure the lifetimes of some weak ETRs and also their brightness temperature variations. The 37/87 GHz full-disk radio intensity contours are superposed on $CaII (k_{3})$ and $H_{\alpha}$ images observed with the Meudon Spectroheliograph (France) for comparing the optical positions and the brightness characteristics of these regions. A similar comparison is also made with the SOHO/MDI full-disk magnetograms and SOHO/EIT images. There appear to be two different classes of weak ETRs. One class is connected with local brightness features seen in $CaII (k_{3})$, $H_{\alpha}$ images and magnetograms. The other class is connected with so-called minor brightness features.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Type
Contributed Papers
Copyright
© 2004 International Astronomical Union