Proteins and DNA Building Blocks Found in Stellar Disk
Astronomers at W. M. Keck Observatory in Hawaii have found – for the first time – some of the basic compounds necessary to build organic molecules and one of the bases found in DNA within the inner regions of a planet-forming disk. The star, known as IRS46 is located in the Milky Way galaxy about 375 light years from Earth, in the
constellation Ophiuchus.
“We see pre-biotic organic molecules in comets and the gas giant planets in our own solar system and wonder, where did these chemicals come from?” said Dr. Marc Kassis, an astronomer at the W. M. Keck Observatory. “The Spitzer Space Telescope is letting us study these young stellar objects in new and revealing ways, giving us exciting clues
about where life may form in the universe.”
The two organic compounds -- acetylene and hydrogen cyanide -- are commonly found in our own solar system, in the atmospheres of the giant gas planets, the icy surfaces of comets, and the atmosphere of Saturn’s largest moon, Titan. Carbon dioxide is widespread in the atmospheres of Venus, Earth, and Mars.
"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 Keck Astronomer Dr. Geoffrey Blake, of the California Institute of Technology. “Now, we can detect these same molecules in the planet zone of a star hundreds of light-years away."
The presence of gas-rich disks around young stars is well known, but little is understood about the chemical structure inside. The discovery of acetylene and hydrogen cyanide in one of these disks will help astronomers better understand these areas around stars where future solar systems may someday form and possibly result in life.
“Spitzer found something very unique -- a young protostar with a dusty disk that, when viewed from Earth, appears tilted on the sky, similar to how some galaxies appear,” Kassis explained. “This viewing angle let the team use Keck data to study the inner regions of the disk. The results told the team exactly how the disk was moving and suggest there may be a stellar wind coming from the inner region. Keck also helped measure the high temperatures and the particle concentration in the disk.”
The dust and gas surrounding a young star blocks visible light, but lets longer wavelengths, such as infrared light, pass through. Astronomers can find out what this gas and dust is made of by separating the light into its component wavelengths, or colors.
Since 2003, the NASA Spitzer Space Telescope has allowed astronomers to use this technique to study molecular compounds in protoplanetary disks of young stellar objects. Spitzer has been used to look at more than 100 sources in five nearby star-forming regions and only one – IRS46 – showed clear evidence of containing the organic compounds in the warm regions close to the star where terrestrial planets are most likely to form.
"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. While the precise events leading up to self-replicating nucleic acids remains unclear, the molecules of acetylene (C2H2) and hydrogen cyanide (HCN) have been shown to produce the base compounds necessary to build RNA and DNA. The team found that the abundance of hydrogen cyanide (HCN) was nearly 10,000 times higher than that found in cold interstellar gas from which stars and planets are born.
"The gases are very warm, close to or somewhat above the boiling point of water on Earth," said Dr. Adwin Boogert, also of Caltech. "These high temperatures helped to pinpoint the location of the gases in the disk."
For More Information:
http://www.spitzer.caltech.edu/Media/releases/ssc2005-26/release.shtml
http://keckobservatory.org/news/science/051220_irs46/051220.html
constellation Ophiuchus.
“We see pre-biotic organic molecules in comets and the gas giant planets in our own solar system and wonder, where did these chemicals come from?” said Dr. Marc Kassis, an astronomer at the W. M. Keck Observatory. “The Spitzer Space Telescope is letting us study these young stellar objects in new and revealing ways, giving us exciting clues
about where life may form in the universe.”
The two organic compounds -- acetylene and hydrogen cyanide -- are commonly found in our own solar system, in the atmospheres of the giant gas planets, the icy surfaces of comets, and the atmosphere of Saturn’s largest moon, Titan. Carbon dioxide is widespread in the atmospheres of Venus, Earth, and Mars.
"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 Keck Astronomer Dr. Geoffrey Blake, of the California Institute of Technology. “Now, we can detect these same molecules in the planet zone of a star hundreds of light-years away."
The presence of gas-rich disks around young stars is well known, but little is understood about the chemical structure inside. The discovery of acetylene and hydrogen cyanide in one of these disks will help astronomers better understand these areas around stars where future solar systems may someday form and possibly result in life.
“Spitzer found something very unique -- a young protostar with a dusty disk that, when viewed from Earth, appears tilted on the sky, similar to how some galaxies appear,” Kassis explained. “This viewing angle let the team use Keck data to study the inner regions of the disk. The results told the team exactly how the disk was moving and suggest there may be a stellar wind coming from the inner region. Keck also helped measure the high temperatures and the particle concentration in the disk.”
The dust and gas surrounding a young star blocks visible light, but lets longer wavelengths, such as infrared light, pass through. Astronomers can find out what this gas and dust is made of by separating the light into its component wavelengths, or colors.
Since 2003, the NASA Spitzer Space Telescope has allowed astronomers to use this technique to study molecular compounds in protoplanetary disks of young stellar objects. Spitzer has been used to look at more than 100 sources in five nearby star-forming regions and only one – IRS46 – showed clear evidence of containing the organic compounds in the warm regions close to the star where terrestrial planets are most likely to form.
"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. While the precise events leading up to self-replicating nucleic acids remains unclear, the molecules of acetylene (C2H2) and hydrogen cyanide (HCN) have been shown to produce the base compounds necessary to build RNA and DNA. The team found that the abundance of hydrogen cyanide (HCN) was nearly 10,000 times higher than that found in cold interstellar gas from which stars and planets are born.
"The gases are very warm, close to or somewhat above the boiling point of water on Earth," said Dr. Adwin Boogert, also of Caltech. "These high temperatures helped to pinpoint the location of the gases in the disk."
For More Information:
http://www.spitzer.caltech.edu/Media/releases/ssc2005-26/release.shtml
http://keckobservatory.org/news/science/051220_irs46/051220.html
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