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Cosmic dust up may best explain dimming of Betelgeuse, Astronomy Now



 
 
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  #1  
Old March 10th 20, 03:23 PM posted to alt.astronomy
a425couple
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Default Cosmic dust up may best explain dimming of Betelgeuse, Astronomy Now

from
https://astronomynow.com/2020/03/08/...of-betelgeuse/

Cosmic dust up may best explain dimming of Betelgeuse
8 March 2020 Astronomy Now

Betelgeuse, as imaged by ESO’s Very Large Telescope and SPHERE
instrument last December. Image: ESO/M. Montargès et al.
Amateur and professional astronomers alike have marvelled at the dimming
of the red supergiant Betelgeuse in the familiar constellation Orion, a
phenomenon some have interpreted as evidence the bloated star is nearly
out of nuclear fuel and on the verge of exploding in a supernova blast.

But astronomers at the University of Washington and the Lowell
Observatory say it’s more likely Betelgeuse is simply doing what red
supergiants do, throwing off gas in its outer atmosphere that absorbs
some of its light on the way to Earth.

“We see this all the time in red supergiants, and it’s a normal part of
their life cycle,” said Emily Levesque, associate professor of astronomy
at the University of Washington. “Red supergiants will occasionally shed
material from their surfaces, which will condense around the star as
dust. As it cools and dissipates, the dust grains will absorb some of
the light heading toward us and block our view.”

Levesque and Lowell’s Phillip Massey carried out observations in
February that allowed them to measure the average surface temperature
across Betelgeuse by analysing the spectra of the light reaching Earth.

Using the 4.3-metre Lowell Discovery Telescope and a spectrometer
equipped with a filter to lower the light’s intensity, the researchers
determined the star’s average temperature on 14 February was about 3,325
Celsius (6,017 Fahrenheit). That’s 50 to 100 degrees cooler than
measurement made in 2004, long before the current dimming began.

The measurements cast doubt on an alternative theory that Betelgeuse’s
dimming has been caused by huge convection cells rising to the surface
and cooling. Levesque and Massey say if that was the case, they would
have seen a much greater decrease in temperature between 2004 and 2020.

“A comparison with our 2004 spectrum showed immediately that the
temperature hadn’t changed significantly,” said Massey. “We knew the
answer had to be dust.”

More observations are planned as astronomers around the world keep tabs
on Betelgeuse and it’s on-going evolution. Regardless of its temperature
and brightness today, the supergiant is still expected to explode in the
next 100,000 years or so when nuclear fusion finally grinds to a halt
and its core collapses.

“Red supergiants are very dynamic stars,” said Levesque. “The more we
can learn about their normal behaviour — temperature fluctuations, dust,
convection cells — the better we can understand them and recognise when
something truly unique, like a supernova, might happen.”
  #2  
Old March 11th 20, 02:21 PM posted to alt.astronomy
Daniel60
external usenet poster
 
Posts: 307
Default Cosmic dust up may best explain dimming of Betelgeuse, AstronomyNow

a425couple wrote on 11/03/2020 1:23 AM:
from
https://astronomynow.com/2020/03/08/...of-betelgeuse/


Cosmic dust up may best explain dimming of Betelgeuse
8 March 2020 Astronomy Now

Betelgeuse, as imaged by ESO’s Very Large Telescope and SPHERE
instrument last December. Image: ESO/M. Montargès et al.
Amateur and professional astronomers alike have marvelled at the dimming
of the red supergiant Betelgeuse in the familiar constellation Orion, a
phenomenon some have interpreted as evidence the bloated star is nearly
out of nuclear fuel and on the verge of exploding in a supernova blast.

But astronomers at the University of Washington and the Lowell
Observatory say it’s more likely Betelgeuse is simply doing what red
supergiants do, throwing off gas in its outer atmosphere that absorbs
some of its light on the way to Earth.

“We see this all the time in red supergiants, and it’s a normal part of
their life cycle,” said Emily Levesque, associate professor of astronomy
at the University of Washington. “Red supergiants will occasionally shed
material from their surfaces, which will condense around the star as
dust. As it cools and dissipates, the dust grains will absorb some of
the light heading toward us and block our view.”

Levesque and Lowell’s Phillip Massey carried out observations in
February that allowed them to measure the average surface temperature
across Betelgeuse by analysing the spectra of the light reaching Earth.

Using the 4.3-metre Lowell Discovery Telescope and a spectrometer
equipped with a filter to lower the light’s intensity, the researchers
determined the star’s average temperature on 14 February was about 3,325
Celsius (6,017 Fahrenheit). That’s 50 to 100 degrees cooler than
measurement made in 2004, long before the current dimming began.


A 50 to 100 degree decrease in just 15 or so years!! Really!!

The measurements cast doubt on an alternative theory that Betelgeuse’s
dimming has been caused by huge convection cells rising to the surface
and cooling. Levesque and Massey say if that was the case, they would
have seen a much greater decrease in temperature between 2004 and 2020.

“A comparison with our 2004 spectrum showed immediately that the
temperature hadn’t changed significantly,” said Massey. “We knew the
answer had to be dust.”

More observations are planned as astronomers around the world keep tabs
on Betelgeuse and it’s on-going evolution. Regardless of its temperature
and brightness today, the supergiant is still expected to explode in the
next 100,000 years or so when nuclear fusion finally grinds to a halt
and its core collapses.

“Red supergiants are very dynamic stars,” said Levesque. “The more we
can learn about their normal behaviour — temperature fluctuations, dust,
convection cells — the better we can understand them and recognise when
something truly unique, like a supernova, might happen.”


At the above rate, it should be a Absolute Zero with-in 2,000 years at
the above rate!!

--
Daniel
 




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