Browsing by Author "Kathiravan, C."

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Coronal Magnetic Field Lines and Electrons Associated with Type III V Radio Bursts in a Solar Flare
(2017) Kishore, P.; Kathiravan, C.; Ramesh, R.; Ebenezer, E.
We recently investigated some of the hitherto unreported observational characteristics of the low frequency (85 35 MHz) type III V bursts from the Sun using radio spectropolarimeter observations. The quantitative estimates of the velocities of the electron streams associated with the above two types of bursts indicate that they are in the range ? 0.13 c 0.02c for the type V bursts, and nearly constant (? 0.4 c) for the type III bursts. We also find that the degree of circular polarization of the type V bursts vary gradually with frequency/heliocentric distance as compared to the relatively steeper variation exhibited by the preceding type III bursts. These imply that the longer duration of the type V bursts at any given frequency (as compared to the preceding type III bursts) which is its defining feature, is due to the combined effect of the lower velocities of the electron streams that generate type V bursts, spread in the velocity spectrum, and the curvature of the magnetic field lines along which they travel. 2017, Indian Academy of Sciences.
Coronal Magnetic Field Lines and Electrons Associated with Type III–V Radio Bursts in a Solar Flare
(Springer India sanjiv.goswami@springer.co.in, 2017) Kishore, P.; Kathiravan, C.; Ramesh, R.; Ebenezer, E.
We recently investigated some of the hitherto unreported observational characteristics of the low frequency (85–35 MHz) type III–V bursts from the Sun using radio spectropolarimeter observations. The quantitative estimates of the velocities of the electron streams associated with the above two types of bursts indicate that they are in the range ? 0.13 c–0.02c for the type V bursts, and nearly constant (? 0.4 c) for the type III bursts. We also find that the degree of circular polarization of the type V bursts vary gradually with frequency/heliocentric distance as compared to the relatively steeper variation exhibited by the preceding type III bursts. These imply that the longer duration of the type V bursts at any given frequency (as compared to the preceding type III bursts) which is its defining feature, is due to the combined effect of the lower velocities of the electron streams that generate type V bursts, spread in the velocity spectrum, and the curvature of the magnetic field lines along which they travel. © 2017, Indian Academy of Sciences.
LOW-FREQUENCY RADIO OBSERVATIONS of the SOLAR CORONA with ARCMINUTE ANGULAR RESOLUTION: IMPLICATIONS for CORONAL TURBULENCE and WEAK ENERGY RELEASES
(2016) Mugundhan, V.; Ramesh, R.; Barve, I.V.; Kathiravan, C.; Gireesh, G.V.S.; Kharb, P.; Misra, A.
We report on the first long baseline interferometer (length ?8 km) observations of the solar corona at 37 MHz that were carried out recently with an angular resolution of ?1?. The results indicate that, (1) discrete radio sources of the aforesaid angular size or even lesser are present in the solar corona from where radiation at the above frequency originates. This constrains the angular broadening of radio sources at low frequencies due to scattering by density turbulence in the solar corona; and (2) the observed sources in the present case correspond to the weakest energy releases in the solar atmosphere reported so far. 2016. The American Astronomical Society. All rights reserved.
LOW-FREQUENCY RADIO OBSERVATIONS of the SOLAR CORONA with ARCMINUTE ANGULAR RESOLUTION: IMPLICATIONS for CORONAL TURBULENCE and WEAK ENERGY RELEASES
(Institute of Physics Publishing helen.craven@iop.org, 2016) Mugundhan, V.; Ramesh, R.; Barve, I.V.; Kathiravan, C.; Gireesh, G.V.S.; Kharb, P.; Misra, A.
We report on the first long baseline interferometer (length ?8 km) observations of the solar corona at 37 MHz that were carried out recently with an angular resolution of ?1?. The results indicate that, (1) discrete radio sources of the aforesaid angular size or even lesser are present in the solar corona from where radiation at the above frequency originates. This constrains the angular broadening of radio sources at low frequencies due to scattering by density turbulence in the solar corona; and (2) the observed sources in the present case correspond to the weakest energy releases in the solar atmosphere reported so far. © 2016. The American Astronomical Society. All rights reserved.