LOW-FREQUENCY OBSERVATIONS OF POLARIZED EMISSION FROM LONG-LIVED NON-THERMAL RADIO SOURCES IN THE SOLAR CORONA

We report observations of circularly polarized emission from the solar corona at 77 MHz during the periods 2006 August 11-18, 2006 August 23-29, and 2007 May 16-22 in the minimum phase between the sunspot cycles 23 and 24. The observations were carried out with the east-west one-dimensional radio polarimeter at the Gauribidanur observatory located about 100 km north of Bangalore. Two-dimensional imaging observations at 77 MHz during the same period with the radioheliograph at the same observatory revealed that the emission region co-rotated with the Sun during the three aforementioned periods. Their rotation rates, close to the central meridian on the Sun, are 4'.6, 5'.2, and 4'.9 +/- 0'.5 per day, respectively. We derived the radial distance of the region from the above observed rotation rates and the corresponding values are approximate to 1.24 +/- 0.03 R-circle dot (2006 August 11-18), approximate to 1.40 +/- 0.03 R-circle dot (2006 August 23-29), and approximate to 1.32 +/- 0.03 R-circle dot (2007 May 16-22). The estimated lower limit for the magnetic field strength at the above radial distances and periods are approximate to 1.1, 0.6, and 0.9 G, respectively.