This flare of the star Betelgeuse explains why it was less visible from Earth

NASA / via REUTERS This four-panel illustration shows how the southern region of the rapidly evolving, bright, red supergiant star Betelgeuse may have suddenly become fainter for several months during late 2019 and early 2020. In the first two panels, as seen in ultraviolet light with the Hubble Space Telescope, a bright, hot blob of plasma is ejected from the emergence of a huge convection cell on the star’s surface. In panel three, the outflowing, expelled gas rapidly expands outward. It cools to form an enormous cloud of obscuring dust grains. The final panel reveals the huge dust cloud blocking the light (as seen from Earth) from a quarter of the star’s surface. NASA/ESA/E. Wheatley (STScI)/Handout via REUTERS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY.

NASA / via REUTERS

The evolution of Betelgeuse

SPACE – What is happening on the star Betelgeuse? Thanks to the images taken by the space telescope Hubblescientists now know that the red supergiant is in the process of ” to re-establish “ after having “experienced a surface mass ejection”reports a study, published this Thursday, August 11 by the Nasa. Yet some observers expected it to explode in supernova. It is not so for the moment, but the star continues to behave strangely.

The shine of thestarlocated in the constellation Orion, began to fade at the end of 2019. Astrophysicists now know that if the star was no longer so visible, it was not that it was about to explode, but was actually hidden behind a cloud of dust, reports NASA.

Betelgeuse, Betelgeuse, Betelgeuse…

This supergiant star experienced a huge mass ejection of its visible surface b… https://t.co/7atAOixClS

— Hubble (@NASAHubble)

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This cloud is the result of“a surface mass ejection”of a magnitude “never seen before” and which caused him to lose a substantial part of its visible surface”. The supergiant expelled 400 billion times more mass than a typical coronal mass ejection, such as those experienced by our Sun.

“We are seeing stellar evolution in real time”

“We had never observed a gigantic mass ejection from the surface of a star”, explains Andrea Dupree, astrophysicist at the Harvard-Smithsonian Center for Astrophysics and co-author of the study. ” We are faced with something that we do not fully understand (…). We are observing a stellar evolution in real time. » Especially since Betelgeuse is gradually regaining its brilliance, seeming to rule out any sign of an upcoming supernova explosion.

Also, the 400-day pulsation rate of Betelgeuse, observed by scientists for 200 years, has, for the moment, disappeared. According to Andrea Dupree, “the cells inside the star responsible for its regular pulsation could be being tossed around like the tub of an out of balance washing machine”. Therefore, if from the outside Betelgeuse seems to have regained its normal appearance, “its surface wriggles like a gelatin dessert, placed on a plate that is shaken, because it is still in the process of rebuilding itself”.

Betelgeuse is enormous, and this has a surprising corollary: its density is very low. Its mass is ~15 times that… https://t.co/DaE4jTFqDY

— Pierre Kervella (@PierreKervella)

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For the Nasa, the observation of Betelgeuse could deepen our understanding of the decline of the red giants. A loss of mass would not necessarily be a sign of an imminent supernova explosion.

See also on The HuffPost: We’ve Never Seen Such a Black Hole