Hubble sees a red supergiant recover from a titanic explosion

Recreation of the explosion recorded by the red supergiant Betelgeuse. / NASA / ESA / Elizabeth Wheatley (STScI)

Science | Astronomy

Betelgeuse expelled into space in 2019 an amount of matter equivalent to several times the weight of the Moon

Betelgeuse is one of the largest known stars. It is so big that, if we put it where the Sun is, Mercury, Venus, Earth and Mars would be inside it, that it would reach Jupiter. Three years ago, this red supergiant "literally exploded," according to astronomers. It blasted matter several times the weight of the Moon into space, and Hubble is seeing how it recovers from such a catastrophe.

In September 2019, the NASA/ESA Space Telescope saw matter moving at high speed through the star's atmosphere. Several ground-based observatories detected months later that Betelgeuse was dimmer, something that intrigued astrophysicists until they came up with an explanation, also thanks to Hubble. They found that, as it moved millions of kilometers away from the star, the ejected material had cooled and formed a cloud of dust that blocked the star's light from Earth.

Illustration showing the changes recorded by Betelgeuse since January 2019, with the explosion and subsequent dust cloud. /

NASA / ESA / Elizabeth Wheatley (STScI)

Our sun routinely ejects parts of its atmosphere in what are known as coronal mass ejections (CMEs), eruptions of electrically charged particles that shoot out into space. If the phenomenon points to Earth, the cloud of particles can cause northern lights and also blackouts, sparks in oil and gas pipelines, interruptions in radio and telephone communications and interference in television broadcasts. in addition to forcing space station astronauts to take refuge in armored compartments. Betelgeuse's surface mass ejection blasted 400 billion times the mass of a typical CME into space, according to NASA. Something that had never been seen before in a star.

Since then, the star, located 600 light years away on Orion's right shoulder, has been recovering little by little. “Betelgeuse is still doing very unusual things right now; the interior is like bouncing”, says Andrea Dupree, associate director of the Harvard-Smithsonian Center for Astrophysics and co-author of a study published in The Atrophysical Journal. The latest observations from Hubble and other telescopes provide clues about how stars like this one lose mass at the end of their lives, before exploding as supernovae.

Betelgeuse put in the place of the Sun would reach the orbit of Saturn. /

ALMA / E. O'Gorman / P. Kervella

However, according to the researchers, Betelgeuse's "surprisingly smug" behavior is not proof that it will soon explode as a supernova. “We have never seen such a large mass ejection from the surface of a star before. Something is happening that we don't fully understand. It's a totally new phenomenon that we can directly observe and resolve surface details with Hubble. We are observing stellar evolution in real time," says Dupree.

That the explosion has altered the gigantic star, with a diameter 1,400 times that of the Sun, shows that its period of expansion and brightness of 400 days has disappeared, at least for now. Astronomers have monitored Betelgeuse's pulsation rate for about 200 years.

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