A coronal mass ejection on the sun photographed by NASA’s Solar Dynamics Observatory NASA Goddard
Astronomers have seen a huge cloud of plasma erupting from the surface of a young sun-like star. This event, known as a coronal mass ejection (CME), was bigger than any we have recorded previously on this type of star, and researchers hope this could improve our understanding of how similar eruptions may have affected our solar system in the past.
CMEs typically occur after stellar flares – known as solar flares on our sun – which are intense bursts of electromagnetic radiation released from a star’s atmosphere. CMEs on the sun are responsible for the spectacular auroras we see on Earth.
Observations of CMEs coming from other stars are scarce because they are faint, and so hard to detect. Now, however, Yuta Notsu at the University of Colorado Boulder and his colleagues have found evidence for a CME from a young star that is more powerful than any we have seen before.
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Using the Transiting Exoplanet Survey Satellite and the Seimei telescope in Japan, they monitored the activity of a star called EK Draconis, 111 light years away and aged between 50 and 125 million years old, between January and April 2020.
On 5 April 2020, the team observed a superflare – an especially large stellar flare – erupting from the surface of EK Draconis. This was followed soon after by a huge release of plasma flying away from the star at 510 kilometres per second, which the researchers suggest is likely to be the early stages of a CME.
They estimated the mass of the plasma to be 10 times larger than that of the biggest CME we have seen from our sun. “This is the largest event detected from a solar-type star,” says Notsu.
Superflares and massive CMEs are only thought to happen once every few thousand years on our sun, says Notsu. On Earth, CMEs have previously damaged power grids and disrupted radio communications. Notsu suggests that if we were to experience events on the scale of what was observed on EK Draconis, there could be even more destruction of infrastructure.
Nature Astronomy DOI: 10.1038/s41550-021-01532-8
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