A group of Japanese astronomers utilized both ground-based and space-based observations to obtain a more comprehensive understanding of a superflare that occurred on a star. This particular flare was initiated by an incredibly large and fast-moving prominence eruption. The findings offer new insights into the mechanisms behind superflares and prominence eruptions on stars, which have remained unclear until now.
Certain stars have been known to unleash superflares that are more than ten times more powerful than the largest solar flare ever witnessed on the sun. These solar flares can generate hot ionized gas that affects the surrounding environment, or space weather. More potent superflares could have an even more significant impact on the evolution of planets that form around these stars or on any life that exists on such planets.
The team, led by Shun Inoue of Kyoto University, used the 3.8-m Seimei Telescope in Japan and the Transiting Exoplanet Survey Satellite (TESS) to monitor V1355 Orionis, a binary star system known to release large-scale superflares frequently. This system is situated 400 light years away in the Orion constellation.
Through continuous, high temporal resolution observations, the researchers successfully captured a superflare. Data analysis revealed that the flare originated from a prominence eruption. While the velocity of the eruption is difficult to measure directly, conservative estimates still surpassed the escape velocity of the star (347 km/s), indicating that the prominence eruption was strong enough to break free of the star’s gravity and develop into Coronal Mass Ejections (CMEs). The prominence eruption was one of the largest ever recorded, carrying trillions of tons of material.
The findings were published as “Detection of a high-velocity prominence eruption leading to a CME associated with a superflare on the RS CVn-type star V1355 Orionis” by Inoue et al in The Astrophysical Journal on April 27, 2023.