EK Draconis illuminates an unimagined picture of how superflares may affect interplanetary space through coronal mass ejections Welcome to the New Year! While Earth celebrated 2022’s arrival with displays of fireworks, the greatest “fireworks show” in our solar system often occurs on the Sun. Its atmosphere is a venue for dynamic sunspots, solar flares, and dramatic encores of released magnetic tension casting plasma particles into the cosmos via coronal mass ejections (CME).
We’ve seen and studied CMEs from our own Sun, and often use these observations to guide our understanding of the broader universe by extrapolating these findings to other stars.
However, actually seeing these distant observations is difficult – but our team did just that.
In 2020, I worked as part of a research team led by Dr. Kosuke Namekata, National Astronomical Observatory of Japan, that successfully witnessed a massive CME taking place on a distant star. On April 5, 2020, we observed the beginning of a CME forming on EK Draconis. At roughly 50-125 million years in age and 111 light-years from Earth, EK Draconis is a young, solar-type star similar to our Sun, making it a prime candidate to make such extrapolations. It’s what our Sun would have looked like 4.5 billion years ago.
Using NASA’s Transiting Exoplanet Survey Satellite (TESS) and ground-based telescopes including Kyoto University’s SEIMEI Telescope, we captured the “first” evidence of a filament eruption – the early phase of a CME associated with a powerful superflare relative to the star’s size and age. This rare observation suggests that a strong CME, 10 times larger in mass than the largest recorded solar CME, can occur from a superflare on a young, Sun-like star.
We held two observations for 32 nights in the spring and winter of 2020. TESS conducted a photometric observation of EK Draconis, which detected how flare emission evolves and decays in optical light. With SEIMEI, we conducted H-alpha spectroscopy of EK Draconis, which detected how cool plasma (filament) moved away from the star (blue Doppler shift = initial phase of CME).
Thirty minutes into observing the filament eruption, researchers observed that the Hydrogen H-alpha hydrogen line caused an absorption and “Doppler shift”, showing the motion of matter at about 10,000 degrees approaching along the line of sight. This appeared to be a CME flying away from the star’s surface.
We were able to catch only the first step in that ejection’s life, but even so, it was a monster, moving at a top speed of roughly 1 million miles per hour!
Why is this important? Stellar superflares have been studied for years, inspiring and guiding us to find evidence of stellar CMEs and their influence on the habitability of planets. This observation reveals a previously unimagined picture of how superflares and CMEs can affect the surrounding interplanetary space – it’s the first observational evidence that ejecta from a solar-type star may shape the evolution of planetary atmospheres and the birth and maintenance of life.
An event like this could tell us more about our Sun, its behavior, and whether superflares and CMEs like those of EK Draconis might be possible. Fortunately, the frequency of severe space weather events on our current Sun is expected to be low (once every few hundred – thousand years), but a massive CME from our own Sun could spell devastating effects on Earth should it happen.
Although our Sun is much older, it suggests that large CMEs of its “early” years may have shaped young-Earth into the world we live in today. Studying CMEs could illuminate the historic evolution of planets in our solar system while serving as a warning beacon for the future.
Research Report: “Probable detection of an eruptive filament from a superflare on a solar-type star”