Sunday, July 18, 2010

Nasa's Hubble Space Telescope discovers 'superheated planet with comet tail'

In the year 1999, scientists detected the planet nicknamed Osiris which is slightly smaller than the largest planet of our solar system i.e Jupiter Orisis is 153 light years from Earth,it came into the eye of scientists when they noticed the minute reduction in the brightness of its star, caused by the planet passing in front of it.

But astronomers at the space agency have only just found that powerful stellar winds are sweeping the "superheated" planet’s atmosphere out behind it. Experts say this has led to the tail-like effect being captured by the Hubble. The "tail" theory had been hinted at previously but not confirmed until now.

In 2003 astronomers used the Space Telescope Imaging Spectrograph, a Hubble instrument, to investigate the planet and its atmosphere but could not prove their theory. The planet, officially called HD 209458b, orbits around the star once every three and a half days, travelling so close to the star that its surface becomes scorched.

Some of this scorched material is released as gas into the atmosphere, and swept by powerful stellar winds into a tail similar to that of a comet. The innermost planet in our Solar System is Mercury, which takes 88 days to orbit the Sun once, 25 times longer than Osiris takes to orbit its star.

Scientists from the University of Colorado used the space agency’s Cosmic Origins Spectrograph, another instrument on the Hubble, which determines the nature of gases by examining how light from stars passes through them.

They found heavy elements such as silicon and carbon in the planet’s atmosphere, which suggested that the planet was being heated to 1000 degrees Fahrenheit (2000° C). The researchers also found that gas was travelling behind the planet at different velocities and in different directions, rather than in a conventional atmosphere, leading them to believe that this material was akin to the planet’s “tail”.

Dr Jeffrey Linsky, who led the study, said it was the first time that astronomers had been able to measure the gas coming off the planet at specific speeds.

"Since 2003 scientists have theorized the lost mass is being pushed back into a tail, and they have even calculated what it looks like," he said. "We think we have the best observational evidence to support that theory. We have measured gas coming off the planet at specific speeds, some coming toward Earth. “The most likely interpretation is that we have measured the velocity of material in a tail." The loss of material caused by the extreme heat and speed of the planet is only very slight, meaning it will take “about a trillion years for the planet to evaporate,” Dr Linksy added.

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