diamond planet

[alokmohan]

Extrasolar planets may have diamond layers<br />CONFERENCE ON PLANET FORMATION AND DETECTION<br />Posted: February 9, 2005<br /><br />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. <br /><br />"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. <br /><br />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 diamond layers inside the planets many miles thick. <br /><br />Some of the already known low- and intermediate-mass extrasolar planets may be carbon planets, which should easily survive at high temperatures near a star if they have the mass of Neptune. Carbon planets would probably consist mostly of carbides, thought they may have iron cores and substanial atmospheres. Carbides are a kind of ceramic used to line the cylinders of motorcycle engines among other things. <br /><br />The planets orbiting the pulsar PSR 1257+12