[meteorite-list] Partial Ingredients for DNA and Protein Found Around Star

[Ron Baalke]

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Whitney Clavin (818) 354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

News Release: 2005-175 			Dec. 20, 2005

Partial Ingredients for DNA and Protein Found Around Star

NASA's Spitzer Space Telescope has discovered some of life's 
most basic ingredients in the dust swirling around a young 
star. The ingredients - gaseous precursors to DNA and protein - 
were detected in the star's terrestrial planet zone, a region 
where rocky planets such as Earth are thought to be born.

The findings represent the first time that these gases, called 
acetylene and hydrogen cyanide, have been found in a terrestrial 
planet zone outside of our own.

"This infant system might look a lot like ours did billions of 
years ago, before life arose on Earth," said Fred Lahuis of 
Leiden Observatory in the Netherlands and the Dutch space 
research institute called SRON. Lahuis is lead author of a 
paper to be published in the Jan. 10 issue of the Astrophysical 
Journal Letters.

Lahuis and his colleagues spotted the organic, or 
carbon-containing, gases around a star called IRS 46. The star 
is in the Ophiuchus (pronounced OFF-ee-YOO-kuss), or "snake 
carrier," constellation about 375 light-years from Earth. This 
constellation harbors a huge cloud of gas and dust in the 
process of a major stellar baby boom. Like most of the young 
stars here and elsewhere, IRS 46 is circled by a flat disk of 
spinning gas and dust that might ultimately clump together to 
form planets.

When the astronomers probed this star's disk with Spitzer's 
powerful infrared spectrometer instrument, they were surprised 
to find the molecular "barcodes" of large amounts of acetylene 
and hydrogen cyanide gases, as well as carbon dioxide gas. The 
team observed 100 similar young stars, but only one, IRS 46, 
showed unambiguous signs of the organic mix.

"The star's disk was oriented in just the right way to allow us 
to peer into it," said Lahuis.

The Spitzer data also revealed that the organic gases are hot. 
So hot, in fact, that they are most likely located near the star, 
about the same distance away as Earth is from our sun.

"The gases are very warm, close to or somewhat above the boiling 
point of water on Earth," said Dr. Adwin Boogert of the California 
Institute of Technology, Pasadena. "These high temperatures helped 
to pinpoint the location of the gases in the disk."

Organic gases such as those found around IRS 46 are found in our 
own solar system, in the atmospheres of the giant planets and 
Saturn's moon Titan, and on the icy surfaces of comets. They have 
also been seen around massive stars by the European Space Agency's 
Infrared Space Observatory, though these stars are thought to be 
less likely than sun-like stars to form life-bearing planets.

Here on Earth, the molecules are believed to have arrived billions 
of years ago, possibly via comets or comet dust that rained down 
from the sky. Acetylene and hydrogen cyanide link up together in 
the presence of water to form some of the chemical units of life's 
most essential compounds, DNA and protein. These chemical units are 
several of the 20 amino acids that make up protein and one of the 
four chemical bases that make up DNA.

"If you add hydrogen cyanide, acetylene and water together in a 
test tube and give them an appropriate surface on which to be 
concentrated and react, you'll get a slew of organic 
compounds including amino acids and a DNA purine base called 
adenine," said Dr. Geoffrey Blake of Caltech, a co-author of the 
paper. "And now, we can detect these same molecules in the planet 
zone of a star hundreds of light-years away."

Follow-up observations with the W.M. Keck Telescope atop Mauna Kea 
in Hawaii confirmed the Spitzer findings and suggested the presence 
of a wind emerging from the inner region of IRS 46's disk. This 
wind will blow away debris in the disk, clearing the way for the 
possible formation of Earth-like planets.

The Jet Propulsion Laboratory manages the Spitzer Space Telescope 
mission for NASA's Science Mission Directorate, Washington. Science 
operations are conducted at the Spitzer Science Center at Caltech. 
JPL is a division of Caltech. Spitzer's infrared spectrograph was 
built by Cornell University, Ithaca, N.Y. Its development was led 
by Dr. Jim Houck of Cornell. 

For graphics and more information about Spitzer, visit 

http://www.spitzer.caltech.edu/spitzer . 

For more information about NASA and agency programs on the Web, 
visit 

http://www.nasa.gov/home/ .

-end-