Saturday, March 9, 2013

Clues of Life's Origins Found In Galactic Cloud

I'm not one to really speculate on this, since I'm a spectroscopist, not an astrobiologist, but I'll give it a shot. There is a BIG difference chemically (and temporally) between what we detect in clouds in star-forming regions and what we detect on comets or any kind of interstellar surface. There's definitely a cause-and-effect thing going on here, but the real gap in knowledge is what's the mechanism to go from cloud consitutents to cometary material (then obviously to planetary surfaces).

What's really interesting in the context of chemistry is the chemical or physical mechanism for generating complex molecular substance in an early protoplanetary system (either in a cloud, or a disk around a young star, or whatever). We can't really attempt to recreate the conditions of space -- we can do cold, we can do fairly low pressures (though obviously not as low as interstellar space), we can make stuff on surfaces, we can even bombard it with an intense and high-energy photons -- but it's mostly just simple models for the intense conditions of a star forming region.

Most of the research does point to the conclusion that most of the complex organic material gets formed on surfaces of various ices or grains -- it's really the only thermodynamically viable way of forming stuff at such extreme conditions. But how do we probe this spectroscopically? It turns out spectroscopy on surfaces kind of sucks (no offense to surface scientists) -- the absorptions are broad and fairly uncharacteristic, especially on a surface with a potentially complex mixture of molecules of both high and low abundance. It turns out the best way to get resolution is to go to gas-phase. Problem here is that it's damn cold! Complex stuff can't get formed sub-20 K temperatures. But we do see stuff, like this molecule, that give us some sense of what's really going on. There's no way to detect whether or not this stuff is being made on ices or grains and then getting heated off by the absorption of a photon, or whatever, but it's likely the case (especially since there is experimental evidence of ethanimine and cyanomethanimine being formed on cold ice surfaces).

Amino acids (and nucleic acids) might be a lot more abundant than we know. But it's likely this stuff sticks to the ices and grains, or gets formed a lot later in the star formation cycle. That being said, finding these molecules that are studied precursors to major biomolecules is a good sign that the field's on the right track (for the most part. There's a lot of old ideas in the field, and with the advent of the next generation of radio astronomy starting this decade, I think we'll start to see a lot more results like this).

Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/ay_hXn8AUpQ/story01.htm

Winter Olympics 2014 powerball numbers freddie mercury Horshack Beady Eye Eric Idle rory mcilroy

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.