Something strange is happening with Betelgeuse and scientists want to know

Credit image: NASA - art illustration of this cycle
Credit image: NASA - art illustration of this cycle

Article by: Andacs Robert Eugen, on 13  August 2022, at 09:55 am Los Angeles time

The red giant star Betelgeuse, one of the brightest stars from the constellation Orion, had a massive eruption, the likes of which astronomers have never seen before.

Betelgeuse first attracted attention in late 2019, when the star, which shines like a red jewel, has partially lost its brightness. The supergiant continued to dim in 2020. Some scientists have speculated that the star will explode as a supernova and since then they want to find out what happened to it.

Now, astronomers have analyzed data from the Hubble Space Telescope and other astronomical observatories and believe that the star had a titanic ejection mass, losing a substantial part of its visible surface.

"I have never seen a huge mass ejection from the surface of a star before. There's something left that we don't understand well," said Andrea Dupree, an astrophysicist at Harvard & Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

"It's a completely new phenomenon that we can directly observe and learn about surface details with Hubble. We track stellar evolution in real time", she added.

Our Sun regularly experiences coronal mass ejections, by which it releases parts of its outer atmosphere, known as the crown. If these solar flares hit Earth, they may have an impact on satellite communications networks and electricity.

But Betelgeuse's surface mass ejection released 400 billion of times more mass than a typical coronal mass ejection from the sun.

The study of Betelgeuse and its unusual behavior allowed astronomers to follow what happens towards the end of one's life stars.

As Betelgeuse burns the fuel in its core, it swells up to massive proportions, becoming a red supergiant. The massive star is 1.6 billion kilometers in diameter.

Eventually, the star will explode in a supernova, an event that it could be briefly visible during the day on Earth. Until then, will face such mass ejections.

But not even losing a significant amount of its mass surface is not a sign that Betelgeuse is ready to explode, according to astronomers.

Astronomers like Dupree studied how the star behaved before, during, and after the eruption, trying to understand what happened.

Scientists believe that the ejected mass came from inside the star, creating shocks and pulsations that triggered an eruption and dislodged a chunk from the star's outer shell, called the photosphere.

The piece of Betelgeuse's photosphere, which weighed several times more than the moon, was released into space. As the mass cooled, it formed a large cloud of dust that blocked the star's light as seen from Earth.

Betelgeuse is one of the brightest stars visible from Earth, so the decrease in its brightness, which lasted for several months, was noticeable both at astronomical observatories and also for amateur telescopes.

Astronomers have measured Betelgeuse's rhythm for 200 years. The pulse of this star is essentially a fading and brightening cycle that lasts 400 days. That pulse has stopped for now - a testament to how big it was the eruption.

Hubble data show that the outer layer of the star has returned to normal, but its surface remains elastic while the photosphere rebuilds.

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