An international team of astronomers has observed the first multi-temperature coronal mass ejection from a young Sun-like star, EK Draconis. The eruption, captured using the Hubble Space Telescope and ground-based observatories, reveals powerful plasma expulsions that may have shaped early planetary atmospheres. These findings suggest ancient solar activity could have influenced the emergence of life on Earth.
Astronomers, led by Kosuke Namekata of Kyoto University, conducted simultaneous ultraviolet observations with the Hubble Space Telescope and optical observations from ground-based telescopes in Japan and Korea. Their target was the young Sun-like star EK Draconis, serving as a proxy for the early Sun billions of years ago.
The observations detected plasma heated to about 100,000 degrees Kelvin expelled at speeds of 300 to 550 kilometers per second. Approximately ten minutes later, cooler gas around 10,000 degrees launched at about 70 kilometers per second. This multi-temperature structure marks the first-ever evidence of such a coronal mass ejection (CME) from EK Draconis, with the high-temperature plasma carrying significantly more energy.
"What inspired us most was the long-standing mystery of how the young Sun's violent activity influenced the nascent Earth," says Namekata. The team reconstructed ancient solar explosions, noting that powerful CMEs in the early solar system likely affected the atmospheres of Earth, Mars, and Venus. These events could have produced strong shocks and energetic particles, potentially stripping atmospheres or triggering chemical reactions that formed biomolecules and greenhouse gases essential for life.
The study deepens understanding of how intense solar activity may have created conditions for life on early Earth and other planets. Success relied on global collaboration: "We were happy to see that, although our countries differ, we share the same goal of seeking truth through science," Namekata added.
The findings appear in Nature Astronomy (2025; DOI: 10.1038/s41550-025-02691-8).