Complex organic molecules found in infant star

Chuck Bednar for redOrbit.com – @BednarChuck

Using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope, astronomers have for the first time found the building blocks of life in the protoplanetary disk surrounding a young star, detecting evidence of carbon-based molecules close to the million-year-old MWC 480.

Karin Öberg, an astronomer with the Harvard-Smithsonian Center for Astrophysics (CfA) and lead author of a paper published in the journal Nature, detected complex cyanides in the star’s protoplanetary disk. This discovery suggests that the rich organic chemistry responsible for the creation of our Earth and Sun also exist elsewhere in the universe.

How is this like our own solar system?

Öberg’s team detected both the complex carbon-based molecule methyl cyanide (CH3CN) and its simpler relative hydrogen cyanide (HCN) in the outer reaches of MWC 480’s protoplanetary disk, a region believed to be similar in nature to our solar system’s Kuiper Belt (an area which is located beyond Neptune and is home to icy objects known as planetesimals).

The early chemistry of our solar system, including that from the period during which the planets formed, is recorded within comets, the researchers explained. As the worlds evolved, comets and asteroids from the outer reaches of the solar system are believed to have seeded the still-evolving Earth with the water and organic molecules required for the eventual formation of life.

“Studies of comets and asteroids show that the solar nebula that spawned our Sun and planets was rich in water and complex organic compounds. We now have evidence that this same chemistry exists elsewhere in the universe, in regions that could form solar systems not unlike our own,” Öberg said in a statement, noting that the molecules discovered near MWC 480 have also been found in similar concentrations in our own solar system’s comets.

Complex cyanides can thrive in forming solar systems

Located approximately 455 light-years away in the Taurus star-forming region, MWC 480 has roughly twice the mass of our Sun, and its disk is still in the earliest stages of development. The disk only recently coalesced out of a cold, dark nebula of dust and gas, and while astronomers have yet to discover any signs of planetary formation there, higher resolution observations could reveal structures similar to the similarly-aged HL Tau.

Cyanides, especially methyl cyanide, are important because they contain the carbon-nitrogen bonds necessary for the formation of the protein building blocks called amino acids. These molecules are efficiently produced in cold, dark interstellar clouds, but experts were not certain if they could form and survive in the energetic environment of a newly forming solar system.

Thanks to observations made using ALMA, the study authors now known that they can easily survive in such conditions, as a far greater abundance of the molecules were found in MWC 480 than would exist in interstellar clouds. In fact, they report that there was enough methyl cyanide in the star’s protoplanetary disk to completely fill every ocean on Earth.

This indicates to astronomers that protoplanetary disks can efficiently form complex organic molecules, and that they can do so in a relatively quick period of time. This rapid formation is also vital to outplace forces that would otherwise rip apart those molecules, they noted, and the region of MWC 480 where this activity takes place would be similar to the comet-forming area of our own solar system (comparatively speaking, though MWC 480 is much larger).

On the prowl for alien life, we are not special

Astronomers speculate that as this solar system continues to evolve, the organic molecules that are found in comets and other icy bodies will ultimately be transferred to environments that are better suited for supporting life. So what does this mean for the search for alien life?

“From the study of exoplanets, we know our solar system isn’t unique in having rocky planets and an abundance of water,” Öberg said in a statement. “Now we know we’re not unique in organic chemistry. Once more, we have learned that we’re not special. From a life in the universe point of view, this is great news.”

The CfA astronomer told redOrbit via email that the discovery of complex cyanides, which she calls “some of the most interesting organics present in our own Solar Nebula,” can be found in “at least one other protoplanetary disk,” which indicates that “something like the Solar Nebula’s complex organic chemistry is present where exo-planets are forming.”

Öberg added that she was impressed with “just how good ALMA is.” She said that it was “really exciting” to work with the instrument, and that it “still blows [her] mind that we can take chemical images of Solar Systems in the making hundreds of light years away. With this new capability we were almost bound to find something really interesting, and of course we did.”

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