Abstract Details
| Name: rohit Affiliation: ncra-tifr Conference ID: ASI2018_649 Title : Characterising weak low radio frequency emission from the Sun. Authors and Co-Authors : Divya Oberoi NCRA-TIFR, Pune Abstract Type : Contributed Talk Abstract Category : Sun and the Solar System Abstract : The Sun is very dynamic at metrewavelengths along both frequency and time, even during periods of low solar activity. A possible reason for this observed variability can be the presence of weak energetic events, which are requisite for nanoflare-based theories of coronal and chromospheric heating. High sensitivity data from new generation instruments like the Murchison Widefield Array (MWA) provide an opportunity to study these weak emissions. The MWA, located in Western Australia, is an excellent instrument to study the Sun at metrewavelengths. It is particularly useful for studying the weak extended emission from the solar corona and spanning angular sizes from few arcmins to the solar size. MWA covers a frequency range from 80 to 300 MHz spanning a large range in coronal heights from 0.08 to 0.65 R$_{sun}$ simultaneously. We study the solar emission during a quiet period using MWA data. We report the presence of impulsive components (< 1 MHz and few seconds) riding on a minute scale slowly varying component in the 100-240 MHz band. These impulsive features must be of non-thermal origin and form a significant fraction (17-- 45%) of the total solar emission. We also find that the flux emitted in the impulsive features is comparable to that in the slowly varying component. The non-thermal emissions detected by the non-imaging analysis technique presented here include the weakest non-thermal low radio frequency emissions reported in the literature yet. Further imaging analysis allows us to detect even weaker non-thermal emission features on the solar disk. Quiet Sun brightness temperature maps reveal the variability of the order of ~ 2-5%. The observed variability shows a spatial association with the structures seen at EUV wavelengths. The results from the non-imaging and imaging analysis of quiet Sun observations from the MWA will be presented at this meeting. |