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Scientists Discover Building Blocks of Life Around Forming Planets

  • JoEllen McBride

FILE - Radio telescope antennas of the ALMA (Atacama Large Millimeter/submillimeter Array) project, in the Atacama desert, some 1500 km north of Santiago, Chile, March 12, 2013. Scientists using the ALMA have detected, for the first time, methanol in the planet-forming disk around a very young star.

FILE - Radio telescope antennas of the ALMA (Atacama Large Millimeter/submillimeter Array) project, in the Atacama desert, some 1500 km north of Santiago, Chile, March 12, 2013. Scientists using the ALMA have detected, for the first time, methanol in the planet-forming disk around a very young star.

The ingredients of life are scattered throughout the universe. New stars are born from the remains of their ancestors, and whatever material doesn't go into the star swirls around it in a disk, building up into planets, dwarf planets, asteroids and comets.

This is how our solar system formed. Scientists understand the mechanism, but they don't know all the ingredients.

Carbon, which is the foundation of life on Earth, is formed in the interior of stars and dispersed at the end of their lives. It has an uncanny ability to combine with other atoms to form complex organic molecules, and amino acids — another essential building block of life. These links of life are found in the dusty shroud that envelops a forming star, as well as in comets and, recently, on the surface of Pluto.

Where they haven't been found is the stage in between, in the disks around young, newly-formed stars where planets form.

Some questions answered

Scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile have detected, for the first time, methanol in the planet-forming disk around a very young star.

The star, named TW Hya, is only slightly smaller than the Earth’s sun, so researchers believe this system looks similar to how our solar system looked when it formed planets.

"Because we now detect [methanol] in disks, we have that missing link between … stars that we don't yet see a disk around and ... comets," explained Catherine Walsh, principal investigator of the study.

This detection shows that methanol can make the transition from star creation into the planet-forming disk, where it can be incorporated into comets and planets.

The methanol was detected in the region that is equivalent to where Pluto and comets are found in our own solar system. However, the TW Hya system is only beginning to form its planets and comets.

NASA's New Horizons mission to Pluto detected organic molecules on the surface and in the atmosphere of the dwarf planet.

William McKinnon, a member of the New Horizons team and professor of Earth and Planetary Sciences at the California Institute of Technology, tells VOA they also have evidence for methanol on Pluto's surface.

NASA's New Horizons team says there is evidence of methanol on Pluto's surface.

NASA's New Horizons team says there is evidence of methanol on Pluto's surface.

The team announced those results at the Lunar and Planetary Science Conference in March.

"The detection of methanol in the disk of TW Hya is an important step in understanding how icy worlds ... form around stars," McKinnon said.

Finding these molecules during the formation of the planets coincides with their detection in the pristine, icy worlds of our outer solar system.

More questions remain

Methanol must be in a gaseous form to be detected. But the disks around these newly formed stars are so cold, their chemicals are expected to be trapped in ice, explains Walsh.

"There is some other chemical process which is releasing methanol from the icy grains into the gas phase," she said.

Her team needs higher resolution data from the ALMA telescope in order to confirm the chemical origin of the methanol.

Also, the amount of methanol detected is lower and closer to the star than predicted by models run by Walsh. The researchers are now using the observed data to modify the chemical ingredients of their models to match what they see in space.

Using ALMA, astronomers have now shown that methanol is present at all stages of planet formation. This leads them to conclude that other complex organic molecules must be present in these planet-forming disks as well, meaning life has all it needs to get started.

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