Intergalactic Origins of Life

Zeroing in on the Intergalactic Origins of Life

Recent discoveries using The Paranal Observatory located in the Atacama Desert in the northern part of Chile have led astrophysicists believe that carbon-based molecules that once floated in interstellar space  were present in the cloud of dust and gas from which our solar system formed, providing the raw materials for life on Earth. These molecules have been observed throughout our galaxy, which is one reason why many believe conditions may also be ripe for life in other parts of the Milky Way, and in billions of galaxies beyond.

By seeking out dusty galaxies – where organic molecules may form in greater abundance – galaxies similar to our own, but at an earlier stage of their evolution, astronomers hope to work out how long these molecules have been abundant in the universe, and therefore how long the conditions suitable for life as we know it have prevailed.

New evidence appears to support the theory that organic molecules are common elsewhere in the universe. A team led by Sara Ellison of the University of Victoria, Canada, has found another galaxy about 2 billion light years away with telltale diffuse interstellar bands (DIBs) by focusing on dusty-looking galaxies, using the Very Large Telescope in Chile.  "Our theory group does simulations on how galaxy structure evolves over time, and my observations can test those theories," she says

The chemical signature of a class of organic compounds called polycyclic aromatic hydrocarbons can be seen in the way they absorb light from distant stars. The molecules are thought to leave a complex pattern of dark bands in these spectra called diffuse interstellar bands (DIBs).

Finding such organic bands in other galaxies could help pin down when organic molecules -the ingredients for life -first become abundant in galactic evolution.

Nobody has worked out what exactly which molecules contribute to the signature of the interstellar bands, so there is some uncertainty over the composition of the material. By observing the bands in many different galaxies, it may be possible to pin down the exact molecule or molecules.

Other research has shown that Dwarf galaxies which are much smaller than ordinary galaxies like our Milky Way and have weaker gravitational fields, are the most common type of galaxy in the universe and makes them a key to understanding how the universe was seeded with various elements billions of years ago.

Only about thirty of the naturally occurring elements are widespread on Earth, and barely half a dozen are of central importance to life. Oxygen, of course, is the most common, accounting for 50 percent of the Earth's crust, followed by silicon. Many of the more obscure elements are more common that the better known: cerinium trumps copper, ditto for lanthanum over nitrogen. Tin is leapfrogged into the top fifty by dysprosium and samarium. Neither is abundance an indicator of criticality to life: carbon is only the fifteenth most common element, but life as we know it would be impossible without it. Of every 200 atoms in your body, only 19 are carbon. Other elements are key to sustaining life if not creating it: iron is a sina qua non for the manufacture of hemoglobin; cobalt for vitamin B12; potassium is critically important for your nerves.

In 1869, Dimitri Mendeleyev published his Periodic Table of the Elements. Scientists before and after Mendeleyev have proposed a spiral galaxy showing the stars link to the elements and to express the astronomical reach of the elements to evoke wonder at the order underlying the universe.

As we advance in our exploration of the Universe and the search for life, we'll most likely discover that one planet's cherished elements are another planet's poison, preferring their lakes of methane or shiny seas of mercury, to our blue seas of oxygen and hydrogen.

Posted by Casey Kazan.

Related Galaxy posts:

Giant Magellan Telescope to Open a New Window on the Universe
Chile's Atacama Desert -World's Observatory Mecca
Eyes on the Cosmos -European Space Agency's Hawk 1 & Hubble's Successor
Harvard-Smithsonian Scientists Zero In On Key Sign of Habitable Worlds
"The Great Silence" -A Galaxy Insight
New Technologies & the Search for  Extraterrestrial Life-A Galaxy Insight
Lonely Hearts of the Cosmos Revisited -NASA's Phoenix Probe & the Search for
Cruising the Goldilocks Zone -The Search for "Super-Earths"
The Milky Way Enigma -How Galactic Forces May Control Life on Earth

Story links:   http://space.newscientist.com/article/dn12911-new-evidence-for-extragalactic-lifeforming-matter.html
http://chandra.harvard.edu/photo/2002/1060/