Indian Institute of Astrophysics Observes Solar Shocks with Radio Telescope

Astronomers from the Indian Institute of Astrophysics (IIA) have made significant strides in solar observation by detecting shocks generated by coronal mass ejections (CMEs) using the Gauribidanur radio telescope and the Visible Emission Line Coronagraph (VELC) payload aboard the Aditya-L1 satellite. This groundbreaking work sheds light on the dynamics of solar activity and its impact on space weather.

The research team utilized the Gauribidanur radio telescope, located approximately 100 kilometers north of Bengaluru, which operates in the low-frequency range of less than 150 MHz. This facility is currently the only dedicated low-frequency radio telescope for observing solar phenomena. The team reported that these solar shocks, akin to sonic booms associated with aircraft, are driven by fast-moving CMEs that create disturbances in the space environment near Earth.

According to the IIA team, “These shocks are primarily driven by the same set of CMEs, all the way from near the Sun through the interplanetary space. Shocks near the Sun are the birth stage of the shocks observed near Earth.” They emphasized that the characteristic signatures of these shocks include intense transient emissions, which can be detected using ground-based radio telescopes.

The recent launch of the VELC, developed by the IIA, has enhanced the ability to identify the CMEs responsible for these shocks. By combining data from the Gauribidanur facility and the VELC, the team precisely estimated the onset distance of a shock resulting from a CME that occurred on May 27, 2024, placing it approximately 130,000 kilometers from the Sun. The shock wave created by this CME propagated at an impressive speed of around 1,700 kilometers per second.

Prof. R. Ramesh, a senior professor at IIA and principal investigator of the VELC project, stated that this observation marks the closest distance from the Sun at which a CME-driven shock and the associated radio transient have been clearly identified to date. He noted that the remarkable results were made possible through the unique low-frequency observing capabilities of the Gauribidanur radio telescope in conjunction with the VELC.

As the sun approaches its maximum phase in the ongoing sunspot cycle 25, the research team anticipates that continuous and synchronized observations using the Gauribidanur facilities and VELC will enable the identification of CME-driven shocks as close as 30,000 kilometers from the Sun. Dr. C. Kathiravan, lead author of the upcoming publication in the Journal of Astrophysics and Astronomy, explained how such a statistical dataset would provide invaluable insights into the workings of the Sun and its connection to disturbances in the near-Earth space.

The IIA’s findings herald a new era of solar observation and understanding, contributing to the global effort to assess the impacts of solar activity on Earth’s space environment. The results of this study will soon be made available in a leading international journal, further advancing the field of astrophysics.