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Betelgeuse is bouncing back after peaking in 2019

The Comeback Kids –

“We’re watching stellar evolution in real time.”

Jennifer Ouellette

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This illustration plots changes in the brightness of the red supergiant star Betelgeuse following the titanic mass ejection of a large piece of its visible surface.

enlarge/ Artist’s vision for 2021 offers a close-up of Betelgeuse’s irregular surface and its giant dynamic bubbles, dotted with distant Star.

European Southern Observatory

This illustration plots changes in the brightness of the red supergiant star Betelgeuse following the titanic mass ejection of a large piece of its visible surface.

Astronomers are still making new discoveries about the red supergiant star Betelgeuse, Betelgeuse Four experienced a mysterious “darkening” a few years ago. This dimming was ultimately attributed to a cold spot and a stellar “burp,” which enveloped the star in interstellar dust. Now, new observations from the Hubble Space Telescope and other observatories reveal more about the events that preceded the dimming.

Betelgeuse appears to have suffered a massive surface attack in 2019 A mass ejection (SME) event that emits 400 times the mass of our sun during a coronal mass ejection (CME). The scale of the event is unprecedented, showing that the CME and SME are distinctly different types of events, according to a new paper published last week in Physics arXiv. (It has been accepted for publication in The Astrophysical Journal.)

Betelgeuse, a bright red star in the constellation Orion, is one of the closest massive stars to Earth, about 700 light-years away. This is an ancient star that has reached a stage where it glows dark red and expands, while the hot core has only weak gravitational control over its outer layers. The star has something like a heartbeat, albeit very slowly and irregularly. Over time, stars cycle through cycles of expanding and then contracting their surfaces.

One of the cycles is fairly regular and takes a little over five years to go Finish. On top of this is a shorter, more irregular cycle that takes less than a year to 1.5 years to complete. While these cycles are easy to track with ground-based telescopes, the changes do not cause the dramatic changes in the star’s light that would cause the changes seen during dimming events.

This illustration plots changes in the brightness of the red supergiant star Betelgeuse following the titanic mass ejection of a large piece of its visible surface. As we reported earlier, astronomers are The strange and dramatic dimming from Betelgeuse was first noticed in December 2019. The star has become so dim that the difference can be seen with the naked eye. The dimming continued, with a 35% drop in brightness in mid-February before brightening again in April 2020.

Astronomers are baffled by this phenomenon and wonder if it is Signs the star is about to go supernova. After a few months, they narrowed down the most likely explanations to two: a brief cold spot on the star’s southern surface (similar to a sunspot) or a cloud of dust making it appear dimmer to observers on Earth. Last year, astronomers determined that dust was the culprit, linked to the brief appearance of cold spots.

The ESO team concluded that a bubble was ejected and pushed Farther out through the star’s outward pulsation — sort of like a star’s “hiccup”. When convection-driven cold spots appear on the surface, the local temperature drop is enough to condense heavier elements, such as silicon, into solid dust, forming a veil that obscures the star’s southern hemisphere brightness.

This illustration plots changes in the brightness of the red supergiant star Betelgeuse following the titanic mass ejection of a large piece of its visible surface.

This illustration plots changes in the brightness of the red supergiant star Betelgeuse following the titanic mass ejection of a large piece of its visible surface. enlarge/

This illustration depicts the change in brightness of the red supergiant star Betelgeuse after a large mass ejection from its visible surface.

NASA/ESA/Elizabeth Wheatley (STScI)

This illustration plots changes in the brightness of the red supergiant star Betelgeuse following the titanic mass ejection of a large piece of its visible surface.

According to the authors of this latest paper, the event was more than a star hiccup. A large convective plume more than a million miles across emerges from deep within the red giant star. The resulting shocks and pulsations are enough to create an SME that blasts a chunk of the star’s photosphere into space. This creates cold spots covered in dust clouds, which explain the dimming.

The red giant just recovered from that catastrophic event recovered in. “Betelgeuse now continues to do some very unusual things; it’s kind of bouncing on the inside,” said co-author Andrea Dupri of the Harvard-Smithsonian Center for Astrophysics, who likened the activity to a plate jelly. Its signature pulsation also ceased—hopefully temporarily—perhaps because the internal convective cells “shocked around like an unbalanced washing machine tub” as the photosphere began a slow process of rebuilding itself. This illustration plots changes in the brightness of the red supergiant star Betelgeuse following the titanic mass ejection of a large piece of its visible surface. “We have never seen the surface of a star before Huge mass ejection,” Dupri said. “We’re left with something we don’t fully understand. It’s an entirely new phenomenon that we can observe directly and resolve with Hubble for surface details. We’re watching stellar evolution in real time.” Webb Space Telescope may be able to detect in infrared light to the ejected material as it continues to move away from the star, which may tell astronomers more about what’s going on — and its effects on other similar stars.

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

List image of ESO/P. Corvera/M. Montargès et al.

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