Center-to-Limb Variation of Solar Bursts Polarization at Millimeter Wavelengths

摘要

Polarization of radio emission from solar flares provides essential information about plasma regimes confined to magnetic field in quiescent, pre-explosion, sudden energy release and decay phases. Observations of polarization are carried out continuously by the first time at two millimeter wavelengths of 6.67 and 3.34 mm (45 and 90 GHz, respectively) by two solar radio polarimeters named POEMAS operating at El Leoncito Observatory, Argentinian Andes. A total of 30 solar flares observed by the radio polarimeters, between 2012 and 2013, were analyzed. The degree of polarization was observed to increase and then decrease as the heliocentric angle increased. We found a weak correlation between the bursts' flux density and their heliocentric angle, i.e. solar bursts with higher flux density slightly tend to occur near the limb.