How Aditya‑L1 Observations Explain the Corona’s Million‑Degree Temperatures

New Delhi, 14 August – The first Indian‑made solar mission, Aditya‑L1, has delivered a set of measurements that illuminate the long‑standing coronal heating paradox. Led by Prof. R. Ramesh of the Indian Institute of Astrophysics, the team examined high‑resolution spectra to pinpoint where and how energy is deposited in the Sun’s outer layers.

Published in Astrophysical Journal Letters, the analysis points to a combination of Alfvén wave dissipation and rapid magnetic reconnection events as the primary drivers that sustain coronal temperatures of 2 million °C and, in extreme cases, up to 40 million °C. These processes compensate for the continual loss of heat through radiation and solar wind expansion.

For context, the Sun’s core burns at roughly 15 million °C, while the visible surface (photosphere) is about 5,500 °C. The unexpected rise to tens of millions of degrees in the corona has been a major unsolved problem in heliophysics.

The same energetic phenomena that heat the corona also trigger solar flares and coronal mass ejections, which can eject billions of tons of plasma into interplanetary space. When such eruptions intersect Earth’s magnetosphere they can create dazzling polar lights and, at the same time, disrupt power transmission, satellite communications, GPS and radio navigation.

Professor Ramesh reports that during a quiet phase of the 11‑year solar cycle the Sun generally launches two to three CMEs per day; at peak activity the count can exceed ten daily. The new insights from Aditya‑L1 therefore help improve models that forecast space‑weather impacts on technological systems.