- 4264 - BETELGEUSE - is it near end of life? - At the beginning of 2020, the red giant star Betelgeuse started to dim significantly. Betelgeuse has been known to vary in brightness, but this one was unusual. It grew much dimmer than usual, and for a longer period. Betelgeuse didn’t explode, and gradually its usual brightness returned. But astronomers were puzzled as to why Betelgeuse grew so dim.
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4264 - BETELGEUSE
- is it near end of life?
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- ( also see Review
4260 also about Betelgeuse - passed by
an asteroid )
-
- One of the
challenges to understanding Betelgeuse is that it’s very different from our
Sun. While the surface of the Sun is very dense, the “surface” of Betelgeuse is
very diffuse. Its diameter is wider than the orbit of Mars but its density is
extremely low. So low that the surface region of the star is almost a vacuum.
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- This means the
outer layer of Betelgeuse is convective, where hot regions of gas rise to the
surface, then cool and sink into the star. So one idea was that a particularly
large region of gas reached the surface and cooled, thus making Betelgeuse
appear dim.
-
- But a new study
finds that Betelgeuse actually dimmed because of stardust. Observations of
Betelgeuse from ESO’s Very Large Telescope (VLT) during the dimming period show
that the dimming wasn’t due to a drop in surface temperature. Instead, it
dimmed because a veil of dust obscured the star, blocking some of its light.
The dust came from the star itself. A large bubble of hot gas rose from the
surface and then cooled to the point that it condensed into dust.
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- What’s interesting
about this discovery is that it shows a new way for heavier elements to get
cast into space. Many of the elements other than hydrogen and helium are born
through core fusion in a star, and these can be thrown into deep space during a
supernova explosion.
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- This new study
shows that stardust can be tossed into space long before a star goes supernova,
while it is still in the red giant stage. Since carbon, nitrogen, and oxygen
would be common elements in these dusty outbursts, they could form complex
molecules that are the raw materials for life.
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- Betelgeuse will
become a supernova eventually. It won’t pose any threat to Earth, but it will
be a wondrous sight. But before then it will likely have several more great
dimmings, which will let astronomers further study the end of one star and the
earliest beginnings of others.
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-
December 10, 2023
BETELGEUSE - is it near end of life? 4264
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Sunday, December 10, 2023 ---------------------------------
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