Building Blocks of Life Detected in Distant Galaxy
for National Geographic News
|February 5, 2008|
The discovery of an amino acid precursor in a far-flung galaxy is fresh evidence that life has potential to form throughout the universe, scientists say.
Researchers using the world's largest radio telescope—the Arecibo Observatory in Puerto Rico—have detected methanimine in the distant galaxy Arp 220.
Researchers had previously detected evidence of formaldehyde, ammonia, hydrogen cyanide, and possibly formic acid in the star-forming region.
Methanimine can form the simplest amino acid, glycine, when it reacts with either hydrogen cyanide and then water, or formic acid.
"The fact that we can observe these substances at such a vast distance means that there are huge amounts of them in Arp 220," said Emmanuel Momjian, a former Arecibo astronomer, now at the National Radio Astronomy Observatory in Socorro, New Mexico.
"It is indeed very intriguing to find that the ingredients of life appear in large quantities where new stars and planets are born."
The scientists warn, however, that Arp 220 has undergone a recent merger and hosts a vibrant star nursery. With new stars living hot and fast, then violently exploding, conditions are probably too turbulent to allow life to evolve.
But the ingredients for life could take root later, when more stable, sun-like stars are born. (Related: "Newborn Planet Found Orbiting Young Star" [January 3, 2008].)
Hitting the Jackpot
The new discovery came during the first of two summers that scientists spent surveying Arp 220's composition using the Arecibo telescope. The details of the find were unveiled at last month's meeting of the American Astronomical Society in Austin, Texas.
Chris Salter, an Arecibo astronomer, likened the chemical survey to a "treasure hunt" that hit gold on the very first night of observing.
Methanimine has been previously detected in our own galaxy and tentatively in the nearby galaxy NGC 253, "but never beyond the neighborhood," he writes with his co-authors in a paper that has been submitted for publication in the Astronomical Journal.
While studying the survey data, co-authors Tapasi Ghosh, an Arecibo astronomer, and Mayra Lebron, a former Arecibo astronomer now at the University of Puerto Rico "said, Something looks an awful lot like a spectral line here, and we said, Pull our other leg," Salter told National Geographic News.
"Slowly, we became convinced."
The team has also looked for direct evidence of glycine but has seen none of its telltale chemistry.
To date, more than 140 molecules have been identified in space, mostly in the neighborhood of the Milky Way. (Get a Milky Way wallpaper.)
Esteban Araya is an astronomer at New Mexico Tech in Socorro and the National Radio Astronomy Observatory.
He said the discovery of methanimine in Arp 220, along with "abundant circumstantial evidence, such as the short time it took life to appear on the early Earth, suggest that life ... may be quite common in the universe."
Moreover, he said, the discovery shows complex organic molecules can exist in very inhospitable environments, such as starburst regions.
The shake-ups during rapid star formation probably created the molecules in the first place—but the chance that they'll yield complex life in such a wild scene is low, Araya pointed out.
"Nevertheless, it is possible that some of the methanimine ... will be trapped in dust grains and will enrich the interstellar medium of Arp220," he said.
"When the tumultuous present activity of Arp220 settles down, new generations of stars like our sun may be formed, and some of the organic molecules trapped in dust grains may enrich newly formed planets."
(Related: "Many 'Earths' Are Out There, Study Says [April 6, 2005].)
Rallying Cry for Arecibo
Astronomers predict that the new discovery will touch off new observation programs at the world's largest radio telescopes, including Arecibo, the National Radio Astronomy Observatory's Green Bank Telescope in West Virginia, and the Very Large Array in New Mexico.
Heightened interest in what such scopes can offer the search for extraterrestrial life will be a shot in the arm for Congressional funding that has been waning, the researchers hope.
Arecibo, in particular, has appeared headed for closure if proposed funding cuts materialize.
"These findings show how important Arecibo Observatory can be for the search of biologically important molecules in space," said Héctor Arce, an astrophysicist at Yale University.
"If Arecibo was able to detect molecules from a galaxy [250 million light-years] away, imagine its potential for searches of complex molecules in our own galaxy."
Salter and his colleagues do have plans to turn Arecibo's power toward the Milky Way—if they can.
Meanwhile, they're pushing ahead with the remainder of their Arp 220 survey.
With a little more analysis, they say, they can be more certain about preliminary evidence that methanol—another organic molecule of interest—can also be found in the galaxy.
And they're eager to tackle a list of 20 other starburst galaxies within reach of the telescope, which could contain similarly exciting molecules, Salter said.
"We are hoping to show that Arp 220 isn't that much of an oddball."
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