Stellar eruptions are phenomena that frequently occur on the surface of stars and are responsible for the emission of plasma and charged particles at high energies. In some cases, these eruptions are so large that they are the source of powerful, ultra-energetic stellar winds that can destabilize the atmosphere of nearby planets. And it’s one of those stellar super-eruptions that a team of astrophysicists recently detected on the star AD Leonis.
Using the new Seimei telescope – located on a hill in Okayama west of Kyoto – astronomers from the Graduate School of Science from the University of Kyoto and the National Astronomical Observatory of Japan, have succeeded in detecting 12 phenomena of stellar eruptions on AD Leonis, a red dwarf located at 16 light years. In particular, one of these eruptions was 20 times larger than those emitted by our own sun.
« Stellar eruptions are sudden explosions that emanate from the surface of stars, including our own sun. On rare occasions, an extremely large super-eruption will occur. This will result in massive magnetic storms which, when emitted by the Sun, can significantly affect the Earth’s technological infrastructure », explique Kosuke Namekata.
Therefore, understanding the properties of super-flares can be vital, but their scarcity means that data from our sun is difficult to collect. This led scientists to search for Earth-like exoplanets and examine host stars. The study was published in the journal Publications of the Astronomical Society of Japan.
AD Leonis: a source of super-eruptions of unusual magnitude
The team reports a long week of observation with AD Leonis’ Seimei telescope – as well as other observation facilities. This red M-type dwarf has lower temperatures than our sun, which causes a high incidence of eruptions. The team expected a number of them to be significant and was amazed to detect a super-eruption during the very first night of observation.
Light curves of the first super-eruption observed by the Seimei telescope. Credits: Kosuke Namekata et al. 2020
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The light from the excited hydrogen atoms of the super-eruption showed a quantityelectrons high energy roughly an order of magnitude greater than typical Sun flares. ” It is the first time that this phenomenon is reported, and it is thanks to the high precision of the Seimei telescope Says Namekata. The team also observed eruptions where the light of the excited hydrogen atoms increased, but did not correspond to an increase in luminosity in the rest of the visible spectrum.
Kazunari Shibata conclut :« More information on these fundamental stellar phenomena will help us predict super-eruptions, and possibly mitigate the damage caused by magnetic storms here on Earth. We may even be able to begin to understand how these emissions can affect the existence – or emergence – of life on other planets. ».
Sources : Publications of the Astronomical Society of Japan
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