Bioast07: Untangling the 'confusion limit'

Astronomers at the University of Arizona are conducting a "deep" survey of one of the strongest sources in the galactic sky - Sagittarius B2N - to try to get a handle on which organic species have been detected in space. D. Halfen of the Univ. of Arizona reported at the conference about recent millimeter-wave work that he and his colleagues have been doing to make progress on identifying new features that are so weakly present that they are just above the noise limit of the detectors. Further complicating this are the forest of emission lines from other dominant species such as methanol. They unveiled a plan to make a detailed accounting for the most abundant species, removing those features from an astronomical spectrum and identifying what new features remain, especially ones important to prebiotic chemistry.

Another detection of water on an extrasolar planet

For the second time, astronomers claim to have found water vapour in the atmosphere of a giant planet (a "hot Jupiter") outside our Solar System. The detection in the extrasolar planet HD 189733b was made using NASA's powerful Spitzer Space infrared Telescope and is reported in the journal Nature.

The team looked for the signal of water absorption in starlight poking through the edges of the atmosphere when the planet passed in front of its star. The planet was discovered in 2005 as it dimmed the light of its parent star by three percent when transiting in front of it. Using Spitzer, Tinetti and the team observed the starlight dim at two infrared bands (3.6 and 5.8 micrometers). “Water is the only molecule that can explain that behaviour,” says Tinetti. Had the planet been a rocky planet with no atmosphere, both these bands and a third one (8 micrometres), recently measured by a team at Harvard, would have shown the same behavior.

Instead of a rocky world like Earth, HD 189733b is large, with a mass similar to that of Jupiter. Located just 4.5 million km from its star, it orbits it in 2.2 days. In comparison, Earth is 150 million km from the Sun and orbits in 365 days. Although water is a key ingredient for biology, the planet is far too hot to harbor life.

Bioast07: Models of complex molecule formation

Steven Charnley of NASA Ames Research Center describes how complicated organic molecules are formed in interstellar clouds. In particular, he describes the gas phase reactions to build up large carbon-chain species, including many known interstellar organic molecules.

Bioast07: Molecular composition in Galaxies

Sergio Martin, of Harvard-Smithsonian Center for Astrophysics, presents an overview on the latest and future studies of chemical composition in galaxies, especially those within the central few hundred parsecs. In these relatively small regions are found very energetic phenomena such as starbursts and emission from material that is accreting into black holes. Dr. Martin focuses on the upcoming Atacama Large Millimeter Array telescope (ALMA) which will have a significant impact on Extragalactic chemistry.

Bioastronomy 2007 conference, Jul 16-20

Astrobiologists from many different fields of science will be gathering this week in San Juan, Puerto Rico for the international conference Bioastronomy 2007. The theme of the meeting is "Molecules, Microbes and Extraterrestrial Life". They will discuss the latest results about the origin, evolution, distribution and future of life in the universe. The meeting is sponsored in part by the National Astronomy and Ionosphere Center and its Arecibo Observatory, which is operated by Cornell University for the National Science Foundation.

We will feature and highlights results from this meeting - and we hope you'll join us for your own discussion or questions.

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