Entry 37229 (Berkeley CSUA MOTD)

Berkeley CSUA MOTD:Entry 37229

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2025/07/12 [General] UID:1000 Activity:popular

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2005/4/17-18 [Uncategorized] UID:37229 Activity:nil

4/17    A Diamond bigger than the Ritz-Carlton Hotel:
        http://xxx.arxiv.org/abs/astro-ph/0504214
        \_ reminds me of those Star Trek:TNG episodes with that big giant
           crystal
           \_ The Crystalline Entity

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xxx.arxiv.org/abs/astro-ph/0504214Marc J Kuchner (Princeton), S Seager (Carnegie/DTM) Comments: 17 pages, 2 figures, submitted to ApJL We suggest that some extrasolar planets < 60 Earth masses will form sub stantially from silicon carbide and other carbon compounds. Pulsar plan ets and low-mass white dwarf planets are especially good candidate memb ers of this new class of planets, but these objects could also conceiva bly form around stars like the Sun. This planet-formation pathway requi res only a factor of two local enhancement of the protoplanetary disk's C/O ratio above solar, a condition that pileups of carbonaceous grains may create in ordinary protoplanetary disks. Hot, Neptune-mass carbon planets should show a significant paucity of water vapor in their spect ra compared to hot planets with solar abundances. Cooler, less massive carbon planets may show hydrocarbon-rich spectra and tar-covered surfac es. The high sublimation temperatures of diamond, SiC, and other carbon compounds could protect these planets from carbon depletion at high te mperatures.