Full Image of Graph
This graph, or spectrum, from NASA's Spitzer Space Telescope tells
astronomers that some of the most basic ingredients of DNA and protein are
concentrated in a dusty planet-forming disk circling a young sun-like star
called IRS 46. These data also indicate that the ingredients -- molecular
gases called acetylene and hydrogen cyanide -- are located in the star's
terrestrial planet zone, the region where scientists believe Earth-like
planets would be most likely to form.
The data were acquired by Spitzer's infrared spectrograph, which split
light from the star's disk into distinct features characteristic of a
particular chemical. The features, seen here as bumps and squiggles, are
like bar codes used in supermarkets to identify different products. In
this case, the products are the two DNA and protein precursors, acetylene
and hydrogen cyanide, as well as carbon dioxide gas. All three gases are
termed "organic" because they contain the element carbon.
The shapes of the features in this spectrum helped pinpoint the location
of the gases in the star's disk. A feature's shape reflects the
temperature of the gas. By comparison with model spectra, astronomers
were able to deduce that the gases are present in regions where the
temperature ranges from approximately the boiling point of water on Earth
(212 degrees Fahrenheit), to nearly a thousand degrees Fahrenheit. Such
hot temperatures place the gases in the star's terrestrial planet zone,
which is sometimes referred to as the "Goldilocks" zone because it is just
right for Earths.
Acetylene and hydrogen cyanide are some of life's most basic starting
materials. If you mix them together in a test tube with water, and give
them some kind of surface on which to be concentrated and react, you'll
get a slew of organic compounds, including many of the 20 essential amino
acids and one of the four chemical units, called bases, that make up DNA.
