Aditya-L1 Data Offers New Clues to Mystery of Sun’s Super-Hot Corona

NEW DELHI — Data from India’s Aditya-L1 mission is giving scientists new insight into a decades-old puzzle in solar physics: why the Sun’s outer atmosphere is dramatically hotter than its visible surface and how it maintains those extreme temperatures despite losing energy through frequent eruptions.

Researchers analyzing observations from India’s first dedicated solar mission say the findings could improve understanding of the processes that continually heat the corona, the Sun’s outermost atmospheric layer.

The study, led by Professor R. Ramesh of the Indian Institute of Astrophysics, was published in the Astrophysical Journal Letters.

Temperatures inside the Sun follow a pattern that has long puzzled scientists. The solar core reaches roughly 15 million degrees Celsius, while the visible surface, or photosphere, is much cooler at about 5,500 degrees Celsius.

Farther away from the core, however, temperatures rise sharply again. The corona typically reaches about 2 million degrees Celsius and, under some conditions, can climb as high as 40 million degrees Celsius.

That unexpected rise in temperature with distance from the Sun’s primary heat source has remained one of the major unresolved questions in solar science.

The corona is also where some of the Sun’s most powerful eruptions originate, including solar flares and coronal mass ejections, or CMEs. Those events can hurl enormous quantities of energy and charged particles into space.

When directed toward Earth, such activity can produce auroras but can also trigger geomagnetic storms capable of interfering with satellites, navigation systems, communications networks and electrical grids.

Ramesh said the Sun can produce two to three CMEs per day during quieter periods. Near the peak of its roughly 11-year activity cycle, the number can increase to 10 or more a day.

Those frequent eruptions carry substantial amounts of energy away from the corona, raising another fundamental question: how does the region continually replace that lost energy while remaining intensely hot?

The latest Aditya-L1 observations provide researchers with additional evidence about the mechanisms that may be responsible for sustaining the corona’s extreme temperatures, potentially bringing scientists closer to explaining one of the Sun’s most persistent mysteries. (Source: IANS)