Betelgeuse: Ready to go Supernova?
2010 06 13
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).
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."
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.
Seeing Red: Will Betelgeuse Go Supernova in 2012? (pdf)
Latest News from our Front Page
Tiny Micro Robots Build Things in ‘Microfactory’
2014 04 17
The teenie-weeniest robot uprising ever might be sooner rather than later due to the work of research institute SRI.
Don’t let these microbots’ size fool you, there is power in numbers and thousands of the robots can work together to perform tasks at dizzying speed.
SRI International has developed a new generation of ant-like robots that can work as ...
’We are not dead yet’: Heartbreaking text messages sent from schoolchildren trapped aboard South Korean ferry
2014 04 17
Passengers on board the South Korean ferry sent heartbreaking messages to their family members just moments before it sank.
Children waiting to be rescued frantically reached for their phones as the boat began to list in a bid to communicate with their loved ones a final time.
Twenty-four people, including five students and two teachers, have been found dead, but 272 are ...
"A world of pure imagination": How Occupy turned to "anarchy"
2014 04 17
In the closing ceremonies of London’s 2012 Summer Olympics, comedian Russell Brand, perched atop the Beatles’ "Magical Mystery Tour" bus, opened his performance by singing the first lines of "Pure Imagination" from the movie Willy Wonka:
Come with me
And you’ll be
In a world of
Artists ’have structurally different brains’
2014 04 17
Artists have structurally different brains compared with non-artists, a study has found.
Participants’ brain scans revealed that artists had increased neural matter in areas relating to fine motor movements and visual imagery.
The research, published in NeuroImage, suggests that an artist’s talent could be innate.
But training and environmental upbringing also play crucial roles in their ability, the authors report.
As in many areas ...
NSA-proof email service goes online
2014 04 17
A new email service that protects its users from the prying eyes of the NSA and other spy agencies has gone online. The service’s creators say it will make encrypted messaging accessible to all and curtail internet snooping.
Germany-based Lavaboom was inspired by Lavabit, the encrypted email service that was believed to have been used by whistleblower Edward Snowden before it ...
|More News » |