Investigation on the source location of flares associated with type II radio bursts using multi-wavelength observations

Abstract

In this paper, a set of 145 type II bursts-associated solar flares observed during the period November1997 to December 2006 has been investigated. The radio bursts have been observed by Culgoora radio spectrograph and X-ray flares have been observed by GOES spacecraft. The main objectives are to study the distribution of locations of flares associated with type II bursts on the Sun and association of type II radio bursts with major solar flares and halo CMEs. Among the different latitudinal bins considered, more number of events occurred in the active latitude range 11-20° in both hemispheres. Shifting of dominance of type II-associated flare events from higher latitudes to equator has been seen from the butterfly diagram. Among the different longitudinal bins, more number of type IIs are found in the solar active longitudes around 50 degrees on both the eastern and western regions and in the range 10-20° west. That might be due to the favorable ambient/source conditions in the solar corona. In addition, the DH type II association with metric type IIs has been found to be nearly absent beyond the east longitude 50°. This east-west asymmetry in the low frequency type II bursts (DH type IIs) may be due to emission directivity of the low frequency radiations produced by CME-driven shocks.