Two-dimensional solar mapping at 5.2 cm with the Siberian Solar Radio Telescope

Abstract

We present two-dimensional solar maps at 5.2 cm computed from one-dimensinal observations with the Siberian Solar Radio Telescope (SSRT), using Earth rotation aperture synthesis techniques. The resolution attained with the E-W branch of the instrument is 15 by 45" for a solar declination of about 23 ~ Maps during the period of June 8 to 13, 1988 clearly show the quiet-Sun background, sunspot and plage associated emission as well as compact sources above the neutral line in some active regions. We found that the latter disappear as the gradient of the longitudinal magnetic field decreases. We also detected emission associated with active regions behind the limb, apparently from unresolved loops, extending up to ~40". The prospects of the SSRT, as a dedicated solar instrument, are discussed.

A model for active region emission at centimeter wavelengths

“…The observing procedure has been described by Alissandrakis, Kundu, and Shevgaonkar (1991). Approximately 7.5 hours of observations were used to produce synthesis maps in total intensity (I) and circular polarization (V) on August 2.…”

“…The strongest component observed in the 2-6 cm range is associated with neutral lines of the photospheric magnetic field (Kundu and Alissandrakis, 1984;Alissandrakis et al, 1992). These sources are associated with emerging flux and with high gradient of the longitudinal magnetic field and they are characterized by extremely steep flux spectra.…”

“…due to perspective effects as the active region crossed the solar disk, ledAlissandrakis, Kundu, and Shevgaonkar (1991) to attribute its origin primarily to plage emission. The similarity of the/~ and L maps implies that the circular polarization was low; indeed, the average degree of the circular polarization over the entire active region was 6% and around 20% at the location of the V peak.…”

New results on microwave emission from active regions of the sun

“…Эта зона является хорошим индикатором энергетического состояния активных областей в целом, она играет ключевую роль в их вспышечной продуктивности. Такие источники вы деляются при синтезировании 2 мерных карт актив ных областей по данным, полученным на ССРТ в течение дня с одномерным разрешением [8]. Один из таких случаев приведен на рис.…”

Μικροκυματικη Εκπομπη Απο Ηλιακα Κεντρα Δρασης

“…Η εντονότερη συνιστώσα που παρατηρείται στα κέντρα δράσης στα εκατοστομε τρικά μήκη κύματος, σχετίζεται με τις ουδέτερες γραμμές του φωτοσφαιρικού μα γνητικού πεδίου (βλ. Kundu and Alissandrakis, 1984, Akhmedov et al, 1986, 1987, Alissandrakis et al, 1992. Στα μήκη κύματος από 2 cm μέχρι 4 cm η συνιστώσα αυτή ονομάζεται "ιδιάζουσα πηγή" (peculiar source) και παρατηρείται μόνο σε κέντρα δράσης με έντονη ενεργότητα (activity).…”