The element binds to oxygen, preventing the formation of water

Nov 2, 2013 08:08 GMT  ·  By
Left: an Earth-like, silicate-based exoplanet featuring oceans. Right: a desolate, carbon-rich worlds
   Left: an Earth-like, silicate-based exoplanet featuring oceans. Right: a desolate, carbon-rich worlds

Investigators with the NASA Jet Propulsion Laboratory (JPL), in Pasadena, California, found in a new theoretical study that carbon-rich worlds, including so-called diamond planets, are very likely to feature only limited amounts of water. The main implication here is that these extrasolar planets are highly unlikely to ever house oceans.

According to the study, planets that form around carbon-rich stars will most likely be very dry, and contain large amounts of carbon, maybe even some layers of diamond. By comparison, Earth appeared around a very carbon-poor Sun, meaning that only limited amounts of the chemical exist here.

Using modeling techniques, JPL scientists were able to assess the concentration of ingredients making up carbon exoplanets, and found that these worlds do not have the icy water reservoirs that are characteristic to silicate-based planets, such as those in the solar system.

The main reason for this “drought” is that carbon tends to capture and bind oxygen over time, meaning that very small amounts of O2 will remain available to form water after bonding with hydrogen. Even if water exists of such exoplanets, it is likely to be found in very short supply.

“If we keep track of these building block [icy asteroids and comets]s, we find that planets around carbon-rich stars come up dry,” says JPL investigator Torrence Johnson. He presented the findings in Denver on October 7, at the American Astronomical Society's Division of Planetary Sciences meeting.

“It's ironic that if carbon, the main element of life, becomes too abundant, it will steal away the oxygen that would have made water, the solvent essential to life as we know it,” adds researcher Jonathan Lunine, from the Cornell University.

This line of study is very important for developing protocols on which astronomers could base their search for Earth-analog planets. The NASA Kepler Telescope has already found numerous such candidates, but experts now need to figure out if these worlds can support liquid water and life.

“All rocky planets aren't created equal. So-called diamond planets the size of Earth, if they exist, will look totally alien to us: lifeless, ocean-less desert worlds,” the CU investigator adds.

Astronomers continue to browse through Kepler data, trying to find as many exoplanets similar to Earth as possible. Focusing on discovering such worlds increases our chances of finding a place where the right conditions for the development of life are met.

The NASA planet-hunting telescope has already identified thousands of exoplanets, and dozens of worlds that are very similar to our own in size, mass, density and other features. A vast volume of data remains to be analyzed, potentially containing even more Earth analogs, Astrobiology Magazine reports.