Astrobiology Magazine

Astrobiology Magazine: "

Carbon World
Date Tuesday, February 08 @ 06:34:06
Topic New Planets



Most of the rocky planets familiar to us are predominantly silicate worlds, but a proposal for carbon or even diamond-like planets may add to the diversity of known solar systems.


Carbon World
based on Princeton Univ. report


The Terestrial Planet Finder will search for Earth-like planets orbiting 250 of the closest stars.
Credit: NASA

Some extrasolar planets may be made substantially from carbon compounds, including diamond, according to a report presented this week at the conference on extrasolar planets in Aspen, Colorado. Earth, Mars and Venus are 'silicate planets' consisting mostly of silicon-oxygen compounds. Astrophysicists are proposing that some stars in our galaxy may host 'carbon planets' instead.

'Carbon planets could form in much the same way as do certain meteorites in our solar system, the carbonaceous chondrites,' said Dr. Marc J. Kuchner of Princeton University, making the report in Aspen together with Dr. Sara Seager of the Carnegie Institute of Washington. 'These meteorites contain large quantities of carbon compounds such as carbides, organics, and graphite, and even the occasional tiny diamond.' Imagine such a meteorite the size of a planet, and you are picturing a carbon planet.

Planets like the Earth are thought to condense from disks of gas orbiting young stars. In gas with extra carbon or too little oxygen, carbon compounds like carbides and graphite condense out instead of silicates, possibly explaining the origin of carbonaceous chondrites and suggesting the possibility of carbon planets. Any condensed graphite would change into diamond under the high pressures inside the carbon planets, potentially forming diamon"