Betelgeuse: Ready to go Supernova?
2010-06-13 0:00

From: newscientist.com


The red supergiant Betelgeuse would extend to Jupiter if it were put in the sun's place in the solar system. A new study suggests it has shrunk by more than 15 per cent since 1993 (Image: A. Dupree/CFA/R. Gilliland/STScI/NASA/ESA)


Pinned prominently on Orion's shoulder, the bright red star Betelgeuse hardly seems like a wallflower. But a new study suggests the giant star has been shrinking for more than a decade.

Betelgeuse is nearing the end of its life as a red supergiant. The bright, bloated star is 15 to 20 times more massive than the sun. If it were placed at the centre of the solar system, the star would extend out to the orbit of Jupiter.

But the star's reach seems to be waning. New observations indicate the giant star has shrunk by more than 15 per cent since 1993. This could be a sign of a long-term oscillation in its size or the star's first death knells. Or it may just be an artefact of the star's bumpy surface, which may appear to change in size as the star rotates.

Betelgeuse is enshrouded by vast clouds of gas and dust, so measuring its size is difficult. To cut through this cocoon, Charles Townes of the University of California, Berkeley, and colleagues used a set of telescopes that are sensitive to a particular wavelength of the star's infrared light.

The team used these instruments to measure the size of Betelgeuse's disc on the sky. Over a span of 15 years, the star's diameter seems to have declined from 11.2 to 9.6 AU (1 AU, or astronomical unit, is the distance from the Earth to the sun).

Ejected Gas

The cause for this reduction is unknown, as it is unclear how red supergiants behave near the end of their lives.

"Maybe there's some instability in the star and it's going to collapse or at least go way down in size or blow off some material, but who knows," Townes, who shared a 1964 Nobel Prize for the invention of the laser, told reporters on Tuesday at a meeting of the American Astronomical Society in Pasadena, California.

The shrinking size could also be evidence of an as-yet-unidentified pulsation in the star, says Graham Harper of the University of Colorado in Boulder, who was not affiliated with the study.

The surface of Betelgeuse is known to wobble in and out, fed in part by the roiling energy of convection beneath its surface. Two such pulsations are already known – one seems to start anew each year, the other every 6 years. Since this observation shows a progressive decrease in the size of the star over 15 years with a consistent set of measurements, Harper says: "I think this is a very nice indication that [Betelgeuse] is getting smaller."

Bumpy surface

But he notes the change in size could be an illusion. Simulations suggest temperature differences in red supergiants can make their surfaces extraordinarily bumpy, causing the star to appear to be a different size when viewed from different angles.

"Often if you look at the simulations, the star is not spherical. It looks like a bad potato," Harper told New Scientist. Betelgeuse is thought to rotate every 18 years or so, which might suggest an especially narrow part of the star recently rotated into view.

Another possibility, Harper says, is that the team is not measuring the surface of the star but a layer of dense molecular gas that some astronomers suspect may hover above it.

The team hopes to get higher-resolution pictures of the star at a variety of wavelengths to determine the origin of the light they are seeing.

Source: newscientist.com



Related Articles
Seeing Red: Will Betelgeuse Go Supernova in 2012? (pdf)


Latest News from our Front Page

4 beheaded in Saudi Arabia less than a week into King Salman's rule
2015-01-30 3:13
Comment: So when will the the "Human rights" promoting liberal west elite decide invade Saudi Arabia like they did Libya? Members of Magic Movement stage a mock execution scene in protest of Saudi Arabia beheading of eight Bangladeshi workers in October 2011. Four people have been executed in Saudi Arabia less than a week after 79-year-old King Salman assumed power following the ...
Swedish Office Block Pushes Microchips on its Staff
2015-01-30 2:12
Sweden is heading over the cliff in multiple areas, all at once. They are pushing the abolition of cash, run amok state feminism, gender war, pacification of the police and perhaps even more frightening: open borders. A policy that have given the country a "gold medal" in asylum seeker acceptance. Run away
Charlie Hebdo: Where Neocons, Zionists, Masons and Communists Converge
2015-01-30 1:20
Charlie Hebdo, raising the banner of revolt, has always regurgitated precisely what the “system” required. Charlie Hebdo (CH) came out of the New Left milieu of the 1960s and is a product of the 1968 revolt against President Charles de Gaulle. It happens that the most famous of the New Left revolts came at a time when (1) the CIA was ...
The Liberation of Auschwitz
2015-01-30 0:12
This article is perhaps a day late, but it will be some time before talk of the Holocaust subsides in the mainstream press, especially now that we are to have a vast new Holocaust Memorial Centre built with £50 million of taxpayers money in central London, to replace the rather unimpressive one that already exists in Hyde Park. In the various ...
Facebook’s New ‘Chinese-style’ Political Censorship System Goes Global
2015-01-29 4:35
Last week 21WIRE reported on Facebook’s new communitarian policy whereby readers can ‘flag’ content as “fake news” if they believe it’s not real, or if they do not like it. In the wake of the Charlie Hebdo False Flag event, the social media giant is now allowing governments to determine what is ‘good free speech’, and what is not. “An article ...
More News »