Multi-temperature coronal mass ejections shed light on solar system origins

Multi-temperature coronal mass ejections shed light on solar system origins
by Riko Seibo
Tokyo, Japan (SPX) Oct 28, 2025

Earth's atmosphere is periodically exposed to coronal mass ejections (CMEs)-large eruptions of solar plasma-but in the early solar system, these events were far more frequent and intense. Scientists from Kyoto University and an international team have analyzed a CME from EK Draconis, a young Sun-like star, to better understand the ancient solar activity that may have shaped early Earth and neighboring planets.

The study was motivated by evidence that young Sun analogues display stellar flares and ejections much more powerful than those observed from our Sun today. These early stellar outbursts are thought to have influenced planetary development by generating space weather capable of modifying atmospheres, producing auroras, and possibly creating the chemical ingredients necessary for life. Massive CMEs from the Sun's youth might have both eroded and altered the primordial atmospheres of Earth, Mars, and Venus.

Historically, detecting the most energetic components of these early CMEs has been a challenge, especially the high-velocity, hot plasma predicted by models. Optical telescopes had previously identified only the cooler, slower-moving fragments of ejected material. To fill this gap, the research team combined simultaneous ultraviolet measurements by the Hubble Space Telescope-which can track plasma at 100,000 Kelvin-and ground-based hydrogen alpha observations to capture cooler gas.

Using this dual approach, they recorded a CME from EK Draconis in real time. Hubble traced the rapid expulsion of hot plasma at 300 to 550 km/s, followed by the cooler component at lower speeds observed in the optical range. This provided the first direct evidence of a multi-temperature CME structure in a solar analogue, demonstrating that hot, fast-moving plasma could carry far more energy than previously observed from cooler components alone.

Lead author Kosuke Namekata stated that reconstructing this type of event in a young star helps clarify how violent early Sun activity contributed to atmospheric changes necessary for complex chemistry and ultimately life. The observations agree with recent theoretical and experimental studies, which suggest that strong CME-driven shocks and energetic particles might manufacture greenhouse gases and biomolecules critical for planetary habitability.

This research relied on extensive international coordination, with facilities and scientists from Japan, Korea, and the United States. The authors emphasized that the collaboration proved highly effective in extending observational capabilities. "We were happy to see that, although our countries differ, we share the same goal of seeking truth through science," said Namekata.

Research Report:Discovery of multi-temperature coronal mass ejection signatures from a young solar analogue