Thursday, October 2, 2014

University Team Finds Signs Of Life On Smallest Exoplanet Ever Discovered

University Astronomers Team Finds Signs Of Life On Exoplanet

Professor Drake Deming
Let a team that found water in the
atmosphere of exoplanet HAT-P11b
A team including several university astronomers has found evidence of water vapor in the atmosphere of a planet about 124 light years away. HAT-P-11b, the planet in question, is now the smallest exoplanet – a planet outside our own solar system – where water has been found.

“It’s not that finding water isn’t very exciting on its own,” said Jonathan Fraine, an astronomy doctoral candidate at this university and the lead author of the study, which was published Sept. 24 in Nature. “But it’s also just that we found anything at all.”

Though even properties of planets in our own solar system can be difficult to measure, Fraine and his colleagues were able to show that significant amounts of water vapor were present in the atmosphere of Hat-P-11b. Water vapor has been discovered on planets the size of Jupiter, Fraine said, but this planet, which is comparable to the size of Neptune, is substantially smaller than any other exoplanet where water vapor is known to exist.

“Even as an astronomer, I’m amazed that you’re able to see the chemical composition of the atmosphere of another planet in another solar system,” Stuart Vogel, professor and astronomy department chairman, said. “And to find water, which is essential to life as we know it, is very exciting.”

To find out so much about something so far away, the astronomers had to be “very clever” with the available instruments, said Ashlee Wilkins, a co-author of the study and an astronomy doctoral candidate at this university. This involved using complex cosmological deduction work and a spectroscopy method pioneered by Drake Deming, an astronomy professor and co-author of the study. Deming won the 2010 Beatrice M. Tinsley Prize from the American Astronomical Society for his work.

The exoplanet HAT-P-11b is four times the size
of Earth, or about the same size as Neptune

Using NASA’s Kepler Space Telescope to observe the planet and the Hubble Space Telescope’s Wide Field Camera 3, the astronomers watched as the planet transited in front of its star.

“When the planet blocks out light from the star, it only blocks out a little bit of light, but we can measure the light that is blocked out and through that we’re able to determine the makeup of the atmosphere,” Fraine said.

They found that a wavelength of 1.4 to 1.7 micrometers, the spectrum of light blocked by water vapor, had been blocked by the planet, indicating the presence of water in the atmosphere.

But to further complicate things, the scientists had to be sure the water vapor did not come from the star itself, as sunspots are known to contain water vapor at times. That’s when the Spitzer telescope came in — it measured the temperature of the sunspots and determined they were too hot to contain any water.

So far, discovered planets of similar size have had heavy layers of clouds that have prevented observation, but this planet had few enough clouds that accurate measurements could be made.

A gas giant with no solid surface and temperatures more than 1,000 degrees Fahrenheit because of its proximity to its star, HAT-P-11b certainly doesn’t have any liquid surface water, but the techniques and technology could eventually lead to the discovery of water vapor on much smaller planets that might be able to support life.

“Ultimately if you could find water vapor on small planets, then you could infer, perhaps, that there was liquid water on the surface if you see the vapor in the atmosphere, and that’s not the case here,” Deming said. “But the fact that you can begin to make the measurements means you’re working your way towards that.”

Though many equate the finding of water vapor to the search for extraterrestrial life, Deming said he isn’t hopeful that there will be a conclusion to that search anytime soon, but that doesn’t diminish the significance of finding water.

“I’m not, myself, expecting to find extraterrestrial life,” Deming said. “I would be happy just to find the molecules.”

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