IIA Study Reveals Thermal Behaviour of Interplanetary Coronal Mass Ejections (ICMEs)

¨     The Indian Institute of Astrophysics (IIA), Bengaluru conducted a 29-year statistical study (1995–2024) on the thermal behaviour of Interplanetary Coronal Mass Ejections (ICMEs).

¨     The study analysed observations at 1 Astronomical Unit (AU), covering Solar Cycles 23, 24, and the rising phase of Solar Cycle 25.

¨     Interplanetary Coronal Mass Ejections (ICMEs) are large solar eruptions that travel from the Sun to Earth and interact with the solar wind and Earth’s geomagnetic field.

¨     ICMEs are the interplanetary counterparts of Coronal Mass Ejections (CMEs), which are massive expulsions of plasma and magnetic fields from the solar corona.

¨     1 Astronomical Unit (AU) is the average distance between the Sun and the Earth.

¨     At 1 AU, ICME plasma can retain its magnetic structure and thermodynamic properties, allowing them to be measured by spacecraft.

¨     The study found that nearly 45% of magnetic ejecta exhibited heating signatures at 1 AU, particularly during the solar maximum phase.

¨     The findings challenge the earlier assumption that ICMEs only cool as they expand through space.

¨     The analysis observed a transition from heating-dominated behaviour in Solar Cycle 23 to cooling-dominated behaviour in Solar Cycle 24.

¨     The study improves understanding of space weather and the evolution of solar eruptions during their journey from the Sun to Earth.