The colossal eruption of the star Dragon warns us of the dangers of the sun

The colossal eruption of the star Dragon warns us of the dangers of the sun

In the search for "potentially habitable" exoplanets, one of the main things scientists look at is stellar activity. While stars like ours, a G-type yellow dwarf (G2V), are considered stable over time, other classes are variable and prone to flare-ups, particularly the M-type red dwarfs. within its habitable zone (HZ), the star's tendency to periodically glow could make these planets completely uninhabitable. Stars like ours may not be as stable as previously thought, according to a new study. While observing EK Draconis, a G1.5V yellow dwarf located 110.71 light-years away, within the confines of the Dragon constellation, an international team of astronomers witnessed a massive coronal mass ejection that made everything we have to pale. never seen in our Solar System.

These observations suggest that these ejections can worsen over time, which could be a dire warning for life here on Earth. The study, which appeared in the December 9 issue of the journal Nature Astronomy, was led by Dr. Kosuke Namekata, a researcher at Kyoto University, the National Astronomical Observatory of Japan (NAOJ) and the National Solar Observatory (NSO). . The study explores a stellar phenomenon known as "coronal mass ejection" (CME), a solar storm. These ejections, which occur regularly with our Sun, are often accompanied by a stellar flare (or a sudden, bright burst of radiation).

When they happen, CMEs send clouds of extremely hot charged particles (plasma) at extremely high speeds into space. While the Earth is protected from charged particles by its planetary magnetic field, a CME could cause significant damage if it hit the Earth head-on. Astronauts in orbit would be exposed to lethal radiation levels, satellites would be disabled, and Earth's infrastructure (such as power grids) would be eliminated.

Earth has experienced several powerful geomagnetic storms over time, the best known example of which was the Carrington event in 1859. Several of these events have occurred in the history of the Earth and are usually several thousand years apart. During the study by EK Draconis, the team of researchers observed evidence that superflares may worsen over time for Sun-like stars.

The research builds on previous research by the co- author Yuta Notsu, who was joined by many of the researchers who conducted this latest study. They showed how young Sun-like stars experience frequent superflars that are tens to hundreds of times more powerful than solar flares. The Sun is known to experience superflars, which seem to happen once every several thousand years. This raised the question: Could a superflare also lead to an equally massive "super coronal mass ejection"?

To investigate this possibility, Namekata, Notsu and their colleagues decided to study EK Draconis, who it is similar to our Sun in size and mass, but it is significantly young by comparison (100 million years compared to our Sun, which is 4.6 billion years old). For their observations, Namekata, Notsu and their colleagues used NASA's Transiting Exoplanet Survey Satellite (TESS) and Kyoto University's SEIMEI telescope to observe EK Draconis (which looks like a young version of the Sun) for 32 nights between winter and spring of 2020.

On April 5, 2020, the team observed EK Draconis explode in a superflare, followed 30 minutes later by a massive ejection of super-hot plasma. As Notsu explained, “this type of mass ejection could, theoretically, also occur on our Sun. This observation can help us better understand how similar events may have affected Earth and even Mars over billions of years. This is what our Sun looked like 4.5 billion years ago. ”

The team was only able to observe the first step in the life of ejection, the 'filament eruption' phase, but it is however, he was able to obtain mass and velocity estimates. According to their study, the cloud was more than ten times larger than the most powerful CME ever recorded by a Sun-like star and had a top speed of around 1.6 million km. If such an eruption were to occur from our Sun, it would have the potential to strip Earth's atmosphere and make our planet largely sterile.

While their findings indicate that the Sun may be capable of such violent extremes. , also suggest that superflars and super CMEs are likely rare for stars as old as the Sun. But as Notsu explained, super CMEs may have been much more common billions of years ago, when our Solar System was still forming. "The atmosphere of present-day Mars is very thin compared to that of Earth," Notsu said. "In the past, we think that Mars had a much thicker atmosphere. Coronal mass ejections can help us understand what has happened to the planet over billions of years ".

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