September 27, 2022

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Betelgeuse is recovering from its highest level in 2019

Betelgeuse is recovering from its highest level in 2019

Zoom / The artist’s 2021 conception provided a close-up of Betelgeuse’s irregular surface and giant dynamic gas bubbles, with distant stars dotted in the background.

European Southern Observatory

Astronomers are still making new discoveries about the red giant star Betelgeuse, which experienced a mysterious “darkness” a few years ago. This dimming is ultimately attributed to a cold spot and a stellar “burp” that covered the star with interstellar dust. Now, new observations from the Hubble Space Telescope and other observatories have revealed more about the event that preceded the blackout.

Betelgeuse appears to have experienced a massive Surface Mass Injection (SME) event in 2019, detonating a mass 400 times the mass of our Sun during coronal mass ejections (CMEs). The sheer scale of the event is unprecedented and indicates that large, medium, and small and medium businesses are different types of events, according to new paper Posted in arXiv Physics last week. (It has been accepted for publication in The Astrophysical Journal.)

Betelgeuse is a bright red star in the constellation Orion.One of the closest massive stars to Earth, about 700 light-years away. It is an ancient star that has reached the stage where it glows dull red and is expanding, with only its hot core having a weak gravitational grip on its outer layers. The star is similar to the heartbeat, albeit very slow and irregular. Over time, the star rotates through periods in which its surface expands and then contracts.

One of these courses is fairly regular, taking just over five years to complete. It is a shorter, more irregular cycle that takes less than a year to 1.5 years to complete. While the cycles are easy to track with ground-based telescopes, the shifts do not cause the kind of drastic changes in the star’s light that would explain the changes seen during the dimming event.

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as we are I mentioned earlierFor the first time, astronomers noticed a strange, dramatic dimming in the light coming from Betelgeuse In December 2019. The star fainted so much that the difference was visible to the naked eye. The dimming continued, with brightness dropping 35 percent in mid-February before shining again in April 2020.

Astronomers have puzzled over this phenomenon and wondered if it is a sign that the star is about to transform into a supernova. After several months, they narrowed the most likely explanations to two: a short-lived cold spot on the star’s southern surface (resembling a sunspot) or a mass of dust that made the star appear faint to observers on Earth. last year, Astronomers decided This dust was primary culpritassociated with the appearance of the cold spot for a short period.

The ESO team concluded that a gas bubble was ejected and pushed out further by the star’s outer pulsation — sort of like a stellar ‘burp’. When a cold spot driven by convection appeared on the surface, the local temperature drop was enough to condense heavy elements (such as silicon) into solid dust, forming a veil that obscured the star’s brightness in the Southern Hemisphere.

This illustration shows changes in the brightness of the red giant star Betelgeuse after the giant mass ejected a large chunk of its visible surface.
Zoom / This illustration shows changes in the brightness of the red giant star Betelgeuse after the giant mass ejected a large chunk of its visible surface.

NASA/ESA/Elizabeth Wheatley (STScI)

According to the authors of this latest research paper, the event was much more than a stellar burp. A large carrying pillar with a diameter of over a million miles appeared from the depths within the red giant. The resulting shocks and pulsations were strong enough to produce an SME, blasting a massive portion of the star’s photosphere into space. This resulted in the cold spot being covered in a dust cloud, which explains the opacity.

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The red giant is just beginning to recover from this disastrous event. “Betelgeuse continues to do some unusual things at the moment; the inside is kind of bouncing back” Co-author Andrea Dupree said: of the Harvard-Smithsonian Center for Astrophysics, similar activity to a plate of Jell-O. Its trademark pulse has also stalled—hopefully temporarily—perhaps because the internal convective cells “roll like an unbalanced washing machine tub” as the photosphere begins the slow process of rebuilding itself.

“We’ve never seen such a massive mass ejection of the surface of a star” Dupree said. “We let something happen that we didn’t fully understand. It’s a completely new phenomenon that we can directly observe and solve surface details with Hubble. We’re watching the evolution of stars in real time.” The Web Space Telescope It may be able to detect ejected matter in infrared light as it continues to move away from the star, which could tell astronomers more about what happened — and its effects on other similar stars.

DOI: arXiv, 2022. 10.48550 / arXiv.2208.01676 (About DOIs).

Picture list by ESO / p. kervila / m. Montargès et al.