Blue Collar Scientist

From Jen over at Skepchick, I learn of a news story reporting the discovery of an amino acid precursor in a distant galaxy, Arp 220. The stories (so far) are published at National Geographic and Discovery, and you can find the original press release here. Although Discovery published last month, I hadn’t noticed it amongst the flood of other news from the AAS conference in Austin last month.

Amino acids were found in space in 1994, when glycine was found in Sagittarius B2¹. Glycine is a very simple amino acid, and serves as an inhibiting neurotransmitter in vertebrates, including humans. Sagittarius B2 is a molecular cloud in the Milky Way - a cold region rich in dust and complex molecules that give birth to stars.

Amino acids or their precursors have since been found in a number of molecular clouds, as well as in meteorites. At least five different amino acids have been reported in the Murchuson meteorite, and in 1994 it was discovered that the meteorite had an excess of left-handed amino acid. Polarized ultraviolet light - which has been found in nebulae such as M42, the big bright nebula in the sword of Orion - can preferentially destroy amino acids of one particular handedness over another. The relative mystery of why all life on Earth utilizes left-handed amino acids might therefore have a celestial explanation. If the first amino acids utilized by life came from space, it is likely there was an excess of left-handed molecules as a result of polarized light from the star forming region that gave birth to the sun and the solar system.

The discovery in Arp 220 is of methanimine, which can form the amino acid glycine when it reacts with hydrogen cyanide and then water, or with formic acid. What’s neat about the discovery is that formaldehyde, ammonia, hydrogen cyanide, and probably formic acid have already been discovered in the galaxy’s primary star-forming region. This is, in other words, a snapshot of some of the raw materials for life, being formed in space.

Over 130 molecules have now been found in space - including sugar. We’re to the point that finding amino acid precursors in space isn’t really all that newsworthy. But to the best of my knowledge, this is the first time that such precursors have been found in a distant galaxy, and the first time they have been found in an active galaxy. That’s pretty cool - it establishes that our local galactic neighborhood isn’t really all that special when it comes to the formation of complex molecules in space.

1. the original discovery was called into serious question, but further, more rigorous study, did confirm glycine in space. [↩]