Feeds

Astronomers eyeball smallest star yet

Just a bit bigger than Jupiter

  • alert
  • submit to reddit

High performance access to file storage

Astronomers searching for extrasolar planets have discovered the smallest star spotted yet - just 16 per cent larger than Jupiter. OGLE-TR-122b was identified during analysis of data gathered during the planet-hunting OGLE project in Chile, New Scientist reports.

The OGLE survey identified almost 200 objects by watching for bodies transiting companion stars. In the case of OGLE-TR-122b, the mini-star passes before Sun-like OGLE-TR-122 once a week, dimming the light reaching Earth from the latter by 1.5 per cent. However, although observers were able to use this dimming to calculate the object's diminutive stature, it was not until it was re-examined by Frederic Pont of Switzerland's Geneva Observatory using the the Very Large Telescope in Chile that its true nature was revealed.

The New Scientist explains: "They used the telescope to study the spectrum of the larger star, which wobbles back and forth because of gravitational tugs from the smaller object. The relatively puny body weighed in at 96 times Jupiter's mass - above the threshold of 75 Jupiter-masses required for a bona fide star, which must also burn hydrogen."

Graphic of OGLE-TR-122b by European Southern Observatory

The discovery has implications for exoplanet hunters, who must when classifying objects take into account both dimming - which determines size - as well as the effects of "wobbles" on neighbouring bodies - which determine mass. Accordingly, Claudio Melo of the European Southern Observatory in Santiago, Chile, issued a note of caution for the organisers of any future space-based planet-hunting operation: "Based only on the light curves, you cannot tell what you are observing. When those space missions fly, we need to do ground-based spectroscopic measurements to confirm the nature of the transiting object."

That aside, the astronomers say this is the first time they have eyeballed a star with a radius comparable to a planet. Small it may be, but it isn't the least massive. That honour goes to a star just 93 times Jupiter's mass, announced early in 2005 by the University of Arizona. But, because that lightweight's transit of a companion object is not visible from Earth, its size is unknown. ®

Related stories

Astronomers identify mysterious 'burper'
Are pulsars gravity-wave generators?
Astronomers spot fun-sized solar system

High performance access to file storage

More from The Register

next story
Video games make you NASTY AND VIOLENT
Especially if you are bad at them and keep losing
Russian deputy PM: 'We are coming to the Moon FOREVER'
Plans to annex Earth's satellite with permanent base by 2030
Solar-powered aircraft unveiled for round-the-world flight
It's going to be a slow and sleepy flight for the pilots
LOHAN's Punch and Judy show relaunches Thursday
Weather looking good for second pop at test flights
Honeybee boffin STINGS OWN WEDDING TACKLE... for SCIENCE
Not the worst place to be stung, says one man
India's GPS alternative launches second satellite
Closed satnav system due to have all seven birds aloft by 2016
Curiosity finds not-very-Australian-shaped rock on Mars
File under 'messianic pastries' and move on, people
Top Secret US payload launched into space successfully
Clandestine NRO spacecraft sets off on its unknown mission
prev story

Whitepapers

Mainstay ROI - Does application security pay?
In this whitepaper learn how you and your enterprise might benefit from better software security.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Mobile application security study
Download this report to see the alarming realities regarding the sheer number of applications vulnerable to attack, as well as the most common and easily addressable vulnerability errors.