A new way to spot planets hidden in their star’s glare

Astronomers have developed a new way to spot planets previously hidden in their star`s glare which would help planetary scientists.

Updated: Oct 18, 2010, 15:59 PM IST

London: Astronomers have developed a new way to spot planets previously hidden in their star`s glare, a breakthrough they claim would help planetary scientists search for heavenly bodies that are much closer to their stars.
The new method, by an international team, makes it far more likely that Earth-like planets could be found close to stars in distant galaxies.

And, using this new optics technology, the astronomers have obtained images of a planet on a much closer orbit around its parent star than any other extrasolar planet previously found, the `Astrophysical Journal Letters` reported.

Installed on the European Southern Observatory`s Very Large Telescope, or VLT, atop Paranal Mountain in Chile, the technology enabled the astronomers to confirm the existence and orbital movement of a new planet.

Beta Pictoris b is a planet about seven to 10 times the mass of Jupiter, around its parent star, Beta Pictoris, 63 light years away.

The system works by using a small piece of glass with a complex pattern etched onto its surface. This Apodizing Phase Plate (APP) blocks out the starlight in a certain way, allowing planets to show up in the image whose signals were previously drowned out by the star`s glare.

"This technique opens new doors in planet discovery. Until now, we only were able to look at the outer planets in a solar system, in the range of Neptune`s orbit and beyond.”

"Now we can see planets on orbits much closer to their parent star," the `Daily Mail` quoted as saying Phil Hinz, the director of the UA`s Centre for Astronomical Adaptive Optics at Steward Observatory.

If alien astronomers were studying our solar system using currently available technology only Uranus and Neptune would be visible. The inner planets, Mercury, Venus, Earth, Mars and Saturn, simply wouldn`t show up in their telescope images, say the planetary scientists.

The newly imaged planet, Beta Pictoris b, orbits its star at about seven AUs (astronomical units). An AU is a distance of around 92955807 miles, or the distance between Earth and the Sun.

Hinz said this a distance where things get especially interesting, because most planets in solar systems are believed to exist between five and 10 AUs from their sun.

The breakthrough, which may allow observers to even block out starlight completely with further refinements, was made possible through highly complex mathematical modelling.

"Basically, we are cancelling out the starlight halo that otherwise would drown out the light signal of the planet," said Johanan Codona, a senior research scientist at the UA`s Steward Observatory who developed the theory behind the technique, which he calls phase-apodisation coronagraphy.

"If you`re trying to find something that is thousands
or a million times fainter than the star, dealing with the
halo is a big challenge," he said.

PTI