Planet with two suns 'discovered'

Washington: An international team, which made the finding through NASA's Kepler spacecraft, says the planet, called Kepler-16b, is about 200 light years from Earth and is believed to be a frozen world of rock and gas, about the size of Saturn.

It orbits two stars that are also circling each other, one about two-thirds the size of our sun, the other about a fifth the size of our sun. Each orbit takes 229 days; the stars eclipse each other every three weeks or so.

Alan Boss, a researcher at the Carnegie Institution for Science in Washington DC and a member of the team, was quoted by the media as saying, "You would never get constant daylight because the two stars are so close together.

"They would come together in an eclipse every 20.5 days and then move apart again. As their separation increased, they would go down at different times, and that could make cocktail hour hard."

In fact, the team, led by Laurance Doyle at the Carl Sagan Centre for the Study of Life in the Universe at the Seti Institute in California, spotted the planet after noticing unusual signals in data collected by the Kepler spacecraft.

Images captured by Kepler's camera showed two stars orbiting each other and producing eclipses as they moved in front of one another. Both stars were small in comparison with our own sun, at about 69 and 20 per cent of the sun's mass. On closer inspection, the footage revealed further eclipses that could not be explained by the movement of the two stars, or an additional third star. Instead, a subtle drop in light from the stars, which amounted to a dimming of only 1.7 per cent, was attributed to an orbiting planet.
The astronomers turned next to a ground-based telescope, the Whipple Observatory in Arizona. With this, they monitored the shifting velocity of the heaviest star as it moved around in its orbit.

Those observations gave Doyle's team the details they needed to reconstruct the orbits of the stars and its planet.

They showed that the two suns orbit each other every 41 days at a distance of about 21 million miles. The planet completes a circular orbit around both stars every 229 days at a distance of 65 million miles, according to the findings published in the 'Science' journal.
Josh Carter, another team member, added: "Kepler-16b is the first confirmed, unambiguous example of a circumbinary planet - a planet orbiting not one, but two stars. Once again, we're finding that our solar system is only one example of the variety of planetary systems nature can create."

Source: Decan Herald, 16-9-2011

Indian American astronomer finds diamond-studded planet Washington

Astronomers led by Indian American Nikku Madhusudhan have discovered a giant planet with an atmosphere and core dominated by carbon, raising the prospect that diamond-studded stars may exist.

Madhusudan, a Banaras Hindu University (BHU) alumnus now at Princeton University, New Jersey, and his colleagues have observed that an extremely hot planet discovered last year has more carbon than oxygen - a feature never observed on a planet until now.

The planet, called WASP-12b, orbits a star about 1,200 light-years from Earth, and appears to have temperatures of nearly 2300°C - hot enough to melt stainless steel, the scientists said in the journal Nature.

A computational technique developed two years ago by Madhusudan while he was at the Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, was used to analyse the atmosphere of the planet.

Like Jupiter, WASP-12b is made largely of gas, only its core contains carbon-based minerals such as diamonds and graphite, said Madhusudhan now a postdoctoral scientist in the department of astrophysical sciences at Princeton.

"A carbon-rich planet has dramatic implications for its interior, its atmosphere, and may compel us to rethink our long-ingrained ideas of planetary formation," he said.

The planet-larger than Jupiter-is windy, blazing hot and so near its star that it circles in a single day compared with the 365 needed for Earth to go round the sun.

While one side of WASP-12b always faces the star and is daylit, and the other is always dark, the planet's strong winds and gaseous nature distribute energy and keep both sides equally warm.

With that much hotness and no solid surface, WASP-12b couldn't support life, Madhusudhan said. That doesn't mean that other carbon planets are devoid of life, he said.

"If life exists on such planets, it has to be able to sustain low oxygen, low water and lots of methane and other hydrocarbons" that would be in the atmosphere, he said.

If there are other planets with more carbon than oxygen, and some have rocky surfaces instead of gaseous ones, such orbs may have rocks made of diamonds and graphite, instead of silicon and oxygen found on Earth, Madhusudhan said, and sand there may be as rare as diamonds are on Earth.

Scientists used US space agency NASA's Spitzer Space Telescope to observe light emitted by the planet WASP12, discovered in 2009 by researchers in the UK-based consortium called Wide Angle Search for Planets (WASP).

Source: Deccan Herald, 9-12-2010

First planet from another galaxy 'discovered'

London: Astronomers have discovered what they claim is the first planet from another galaxy.

A team at Germany's Max Planck Institute for Astronomy has found the planet, called HIP 13044 b, around a star which seems to be an interloper from another galaxy - by the way its gravity caused its host star to wobble.

Curiously, the star also contains fewer heavy elements -- thought to be needed to build planets -- than any other planet-hosting star yet discovered, the 'New Scientist' reported.

The planet, which is 1.25 times as massive as Jupiter, lies 2300 light years from Earth and orbits a bloated, ageing star slightly less massive than the sun.The host star, called HIP 13044, is a member of a group of stars called the Helmi stream that have unusual, elongated orbits that bring them far above and below the disc of the galaxy where sun and most other Milky Way stars reside.

The Helmi stars are thought to be remnants of a small galaxy torn apart by the Milky Way some 6 billion to 9 billion years ago.

"This cosmic merger has brought an extragalactic planet within our reach," said team member Rainer Klemen

In addition to its unusual origins, the host star is puzzling because it has fewer elements heavier than hydrogen and helium than any other star known to host a planet. Its light spectrum suggests it has just 10 per cent as much iron as the previous record holder, and only 1 per cent as much as the sun, say the astronomers.

Planets are thought to form from discs of gas and dust left over from the formation of the parent star. In the prevailing theory of planet formation, called core accretion, dust grains stick together to form rocky worlds, and some of these rocky bodies then grow massive enough to attract surrounding gas, becoming gas giants like Jupiter.

Dust is made up of heavy elements, so stars depleted in these elements would have a hard time making planets in this scenario.

"This suggests the planet formed another way," said Alan Boss of the Carnegie Institution of Washington, DC, who was not a member of the team.

He added: "The fact that the star is also likely to have come from somewhere other than the disc of our galaxy makes it even more remarkable, and supports the suspicion that planetary systems are rife in the universe."

Source: Deccan Herald , 19-11-2010