Mysterious dimming of Betelgeuse which has puzzled astronomers in late 2019 and early 2020 could be due to a traumatic outburst.
The mysterious dimming of Betelgeuse in late 2019 and early 2020 has puzzled astronomers around the world. Some believed that it signaled the star’s upcoming explosion. But then the dimming abruptly stopped.
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Thanks to observations by NASA’s Hubble telescope we now know that the dimming periods were most likely caused by the ejection and cooling of dense hot gases and that the star may be going through another dimming period about a year earlier than expected.
This large amount of dense hot gas moving outwards through Betelgeuse’s extended atmosphere might have cooled and formed a dust cloud that partially blocked the star’s light as seen from Earth.
The gas was moving at 200,000 miles per hour.
By February 2020, the star had lost more than two-thirds of its brilliance, a dimming visible even to the naked eye.
This spectral plot is based on Hubble Space Telescope observations from March 2019 to February 2020.
“With Hubble, we had previously observed hot convection cells on the surface of Betelgeuse, and in the fall of 2019, we discovered a large amount of dense hot gas moving outwards through Betelgeuse’s extended atmosphere. We think this gas cooled down millions of miles outside the star to form the dust that blocked the southern part of the star imaged in January and February,” said Andrea Dupree, associate director of the Center for Astrophysics | Harvard & Smithsonian, and lead author on the study.
“The material was two to four times more luminous than the star’s normal brightness. And then, about a month later the south part of Betelgeuse dimmed conspicuously as the star grew fainter. We think it possible that a dark cloud resulted from the outflow that Hubble detected. Only Hubble gives us this evidence that led up to the dimming.”
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Another surprise for scientists was that Hubble revealed that the detected plasma was not ejected from the star’s rotational poles as predicted by stellar models.
These observations suggest that material can be driven off from any part of the star’s surface.
Based on data from Hubble, Betelgeuse is losing mass at a rate of 30 million times higher than the Sun.
However, recent activity resulted in a loss of roughly two times the normal amount of material from the southern hemisphere alone.
While all stars lose material no one knows how this happens.
Betelgeuse is a variable star, but its rising and falling in brightness aren’t noticeable to casual observers.
The red supergiant typically goes through brightness cycles lasting around 420 days. But since the previous minimum happened in February 2020, this new dimming is over a year early.
Betelgeuse is about 700 times bigger than our sun. If you were to replace it with our sun it would completely swallow the asteroid belt.
The star is coming to the end of its life cycle, sometime in the next 100,000 years.
Scientists note further observations will be undertaken in late August. That’s when the star returns to the night sky and can be seen by telescopes again.
Scientists published the new study in The Astrophysical Journal this Thursday.