March 20, 2008 | 12:02 am

Hubble finds organic molecule on exoplanet

Posted by Adam Wills

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JPL announced today that astronomers have detected methane on a Jupiter-sized exoplanet in the constellation Vulpecula. While the planet itself is not capable of supporting life, the presence of the organic compound was detected by using an instrument about the Hubble Space Telescope, Nicmos (Near Infrared Camera and Multi-Object Spectrometer), to measure the absorption of starlight in the atmosphere of the planet, HD 189733b. (New York Times)

“The big news is that we were able to do this at all,” said Mark Swain of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., the lead author of the study, being reported Thursday in the journal Nature. Other members of the team, which used the Hubble Space Telescope, were Gautam Vasisht of the propulsion lab and Giovanna Tinetti of University College London.

The work, they said, represents a shift from barely detecting the existence of so-called exoplanets to probing them chemically.

“We are able to start studying the conditions and chemistry of exoplanet atmospheres,” Dr. Swain said at a news conference on Wednesday. “That’s a very exciting development.”

David Charbonneau, an astronomer at the Harvard-Smithsonian Center for Astrophysics who was not part of the team, called the detection “both persuasive and important.”

Sara Seager, a planetary theorist at M.I.T., called it “another great day for exoplanets,” and a “tipping point” for the study of their detailed properties, though she cautioned that the findings still needed to be duplicated.

“Hubble was never been designed to make measurements like this,” she said. “This is pushing the telescope to its limits.”

She said she was looking forward to the day when the experiment would be repeated on Earth-like planets with the much more powerful James Webb Space Telescope, set to be launched in 2013. In that case, she said, the existence of methane and water would be indicative that the planet was habitable.

 

But given that HD 189733b is about 1,700 degrees Fahrenheit, the possibility of finding life there is pretty slim. (OK Trekkies, repeat after me: It’s life Jim, but not as we know it.)

One lingering puzzle, [Dr. Adam Burrows, a theorist from Princeton University],  said, is why they did not detect carbon monoxide in the planet’s atmosphere. The models, he said, suggest that at high temperatures that molecule is more likely to form than methane, which predominates in colder regions.

Dr. Burrows theorized, however, that if the planet was tidally locked — with one side always facing its sun and being roasted while the other faces away and freezes — “the hot side would have more carbon monoxide, the cold one more methane.”

During the transits observed by Hubble, he pointed out, the starlight passes through the dividing line, or terminator, between the hot side and the cold side, where fierce winds might be blowing redistributing heat and chemical species around the planet.

But nobody really knows how chemistry, climate and cosmic history are manifested on these planets. Dr. Swain said he hoped to perform similar measurements on a half dozen other so-called transiting planets that are within reach.

Dr. Burrows said, “A lot of other shoes are about to drop in this subject.”

But time is of the essence. Hubble will have four more years if its scheduled refurbishment by astronauts goes well this August, but the other warhorse of the effort, the Spitzer, has only a year to go before it runs out of the cryogenics that keep its infrared detectors cold and sensitive.

“People are frantic to get as much data as they can in short term,” Dr. Burrows said.

 

Above image ESA, NASA and G. Tinetti (University College London, UK & ESA) via New York Times.