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At the end of last year, there was news that the star Betelgeuse significantly faded, in the end its brightness fell up to about 40% of its usual brightness. It fueled the popular speculation that the red super giant will soon explode as massive supernova.
But astronomers have softer theories that explain tarnishing stars. Scientists from the University of Washington and Lowell Observatories believe they have another assumption: Betelgeuse fades not because she’s about to explode, but simply because it’s in a dust cloud.
In an article in the Astrophysical Journal Letters and published on arXiv preprints site, Emily Levesque, associate professor UW astronomy, and Philip Massey, an astronomer at the Lowell Observatory, Betelgeuse’s observations were reported in February. The Flagstaff, Arizona Observatory, calculated average temperature of a star’s surface. They found that Betelgeuse is much warmer than expected since tarnishing was supposed to cause cooling of the surface of the star.
New calculations confirm the theory that Betelgeuse – like many red supergiant stars – probably dropped some material from its outer layers.
We see it all the time in the red supergiants and it’s normal part of their life cycle, ”said Levesque. Red supergiants from time to time they drop from its surface a substance that condenses around the star in the form of dust. When it cools and dissipates, dust particles will absorb part of the light heading towards us and block the review.
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Astronomers expect Betelgeuse to explode as a supernova in over the next 100,000 years, when its core collapses. According to Massey, the diminution of the star that began in October is not necessarily a sign of the inevitable appearance of a supernova stars.
According to one theory, the newly formed dust absorbed part of the world from Betelgeuse. “An easy way to find out is to determine Betelgeuse’s surface temperature, “said Messi.
Measuring the temperature of a star is not an easy task. Scientists can’t just point the thermometer at the star and get readings. But, looking at the spectrum of light emanating from a star, astronomers can calculate her temperature.
“Emily and I talked about Betelgeuse and we both agreed that the obvious thing is to get spectrum, “- said Messi. “I already had planned observation time on Lowell Discovery 4.3-meter telescope and I knew I could get a good range even though Betelgeuse is still remains one of the brightest stars in the sky. ”
Light from bright stars is often too strong for detailed spectrum but massey used a filter that effectively “damped” the signal so that they can analyze the spectrum for specific signature: light absorption by oxide molecules titanium.
According to Levesque, titanium oxide can form and accumulate in the upper layers of large, relatively cold stars, such as Betelgeuse. It absorbs light waves of a certain lengths, leaving control “marks” in the spectrum of red supergiants that a scientist can use to determine surface temperature of the star.
According to their calculations, the average Betelgeuse surface temperature is 14 February 2020 was about 3325 degrees Celsius, or 6 017 degrees Fahrenheit. It’s only 50-100 degrees Celsius is lower than the temperature the team including Massy and Levesca calculated as Betelgeuse surface temperature in 2004 year. Years before her dramatic blackout.
Astronomers observed clouds of dust around other red supergiants, and additional observations may reveal a similar the mess around Betelgeuse.
Over the past few weeks Betelgeuse has again begun to recruit brightness, albeit a little. Even if recent blackout did not indicate that the star will explode soon, for Levesque and Massey it’s not reason to stop watching the sky.
“The red supergiants are very dynamic stars,” said Levesque. “The more we can learn about their normal behavior – fluctuations in temperature, dust, convection cells – the better we can understand them and recognize when it can happen something truly unique, such as a supernova. ”
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