Feeds

Staring at the surface of an alien star

Squashed, fast and cool

The smart choice: opportunity from uncertainty

Scientists have taken the first ever pictures of the surface of an alien Sol-like sun.

Actual image returned by the interferometer. Credit: Ming Zhao, University of Michigan

The team, led by astronomers at the University of Michigan, made the observations of the relatively nearby (15 light years away) star Altair. They used four of the six telescopes at Georgia State University's Centre for High Angular Resolution Astronomy (CHARA) interferometric array on Mount Wilson, California.

Astronomers already knew Altair was oddly shaped: the star is 22 per cent wider than it is tall, thanks to the speed of its rotation. At its equator it is spinning 638,000mph, roughly 60 times faster than our our sun.

"It's really whipping around and that's why, of course, it's spread out like a twirling ball of pizza dough," said Monnier, an assistant professor of astronomy at the University of Michigan.

In 1924 astronomer Hugo von Zeipel predicted that rapidly spinning stars would bulge. He also speculated that their equators would be much cooler than their poles, by virtue of the greater distance from the heat of the solar core.

The new images are the first that confirm the idea, but also reveal more about this predicted variation in temperature across the surface: the bulge is much cooler than standard models had predicted.

"This image can only be made with a telescope the size of a football arena. I dare say that we may never create a single telescope mirror this large, but we can do this today with interferometry (a technique to resolve an image using multiple beams)," said Monnier.

The image has been made possible by recent advances in fibre optics. This allows the researchers to combine the images from each telescope in such a way as to clean up some of the distortion from the Earth's atmosphere.

Optical interferometry has been used recently to discover details on the surface of much larger stars: helium burning red giants, for example. But this is the first time anyone has produced images of the surface of a hydrogen burning star like our own. ®

The Power of One Infographic

More from The Register

next story
World Solar Challenge contender claims new speed record
One charge sees Sunswift travel 500kms at over 100 km/h
SMELL YOU LATER, LOSERS – Dumbo tells rats, dogs... humans
Junk in the trunk? That's what people have
The Sun took a day off last week and made NO sunspots
Someone needs to get that lazy star cooking again before things get cold around here
Boffins discuss AI space program at hush-hush IARPA confab
IBM, MIT, plenty of others invited to fill Uncle Sam's spy toolchest, but where's Google?
Bad back? Show some spine and stop popping paracetamol
Study finds common pain-killer doesn't reduce pain or shorten recovery
Forty-five years ago: FOOTPRINTS FOUND ON MOON
NASA won't be back any time soon, sadly
Jurassic squawk: Dinos were Earth's early FEATHERED friends
Boffins research: Ancient dinos may all have had 'potential' fluff
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.