Organic molecules observed in nascent star system

Hydrogen cyanide and methyl cyanide have been found in the disk surrounding a million-year-old star.
By Andrew McDonald | Apr 09, 2015
A team led by Karin Oberg of the Harvard-Smithsonian Center for Astrophysics (CfA) has found the first evidence for complex organic molecules in the protoplanetary disk surrounding a young star. According to a CfA statement, Oberg and colleagues used the Atacama Large Millimeter/submillimeter Array (ALMA) to study the young star system.

The star in question is MWC 480, which is a mere million years old. It is two times the Sun's mass and is 455 light-years away in the Taurus star-forming region. Although ALMA has yet to find signs of planets coalescing in the disk of dust and gas surrounding MWC 480, future observations at greater resolution might uncover such objects.

The current observations have revealed that the colder outer regions of the disk around MWC 480 contain hydrogen cyanide (HCN) and the more complex organic molecule methyl cyanide (CH3CN). The outer reaches of the disk might be similar to the Kuiper Belt in our own solar system, in which short-period comets and dwarf planets reside beyond the orbit of Neptune.

The carbon-nitrogen bonds in cyanide molecules are necessary for the generation of amino acids, the building blocks of proteins. The cyanides detected around MWC 480 occur in far greater quantities than in interstellar clouds. This points to a swift formation of cyanide molecules in protoplanetary disks that cancels out the radiation and shock waves that could destroy them. The cyanide molecules occur between 4.5 and 15 billion kilometers from MWC 480, the distance at which comets would be forming.

"Studies of comets and asteroids show that the solar nebula that spawned our Sun and planets was rich in water and complex organic compounds," Oberg said. "We now have evidence that this same chemistry exists elsewhere in the universe, in regions that could form solar systems not unlike our own."

The new findings have been published in the journal Nature.


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