Sunday, December 21, 2008

Old scope, sexy new applications: sizing up planets

The University of Hawai'i's 2.2-meter telescope is older than nearly half of Hawai'i's population, and it's a fraction of the size of newer scopes, but it's still doing good science.

In part, you can thank for that the cutting edge instrumentation that's being bolted on to the aging mirror.

(Image: UH 2.2-meter telescope dome on Mauna Kea. Credit: Karen Teramura.)

The telescope's latest claim to fame: it was used to measure the exact size of a planet that orbits around a star in our Milky Way that is 300 light years from Earth. The star is called WASP-10.

The telescope was built in 1970, making it 38 years old. Median age of Hawai'i's population in the 2000 census was 39.7. And among the newest telescopes, the twin Kecks are each 10 meters across and the Subaru and Gemini are both in the 8-plus range.

In its most recent publicized feat, the UH 2.2-meter scope was fitted with a camera that can measure light so accurately, the scientific team says, that it could “detect the passage of a moth in front of a lit window from a distance of 1,000 miles.”

By measuring how much the light from a distant star dims when a planet passed in front of it, the device could be used to determine the diameter of the planet

The research was done by a UH Institute for Astronomy team led by astronomer John Johnson. He worked with astronomer Joshua Winn of MIT, MIT graduate student Joshua Carter, and Georgia Institute of Technology student Nicole Cabrera.

The camera, designed by Institute astronomer John Tonry, is amusingly named OPTIC, for Orthogonal Parallel Transfer Imaging Camera. The camera is a digital model similar to your home digital, but stupendously more powerful.

Not long ago, astronomers had no way to detect or measure the existence of planets around stars other than our Sun.

More recently, they've been unable to detect anything but the most massive planets around distant stars.

For measuring stars the size of our Earth, OPTIC can't quite do that, but it hints at the possibility.

"This new detector design is really going to change the way we study planets. It's the killer app for planet transits," Winn said.

For now, the research team announced it was able to use OPTIC to measure a Jupiter-sized planet around WASP-10. Using other techniques, the mass of the planet, itself known as WASP-10b, had been calculated. When OPTIC measured its diameter, astronomers were able to calculate its density.
In the world of astronomy, this is real sexy stuff. A paper on the discovery is to be printed in the journal Astrophysical Journal Letters.

For more information:

© 2008 Jan W. TenBruggencate

No comments: