Recent results have shown that many of the known extrasolar planetary systemscontain regions which are stable for both Earth-mass and Saturn-mass planets.Here we simulate the formation of terrestrial planets in four planetary systems-- 55 Cancri, HD 38529, HD 37124, and HD 74156 -- under the assumption thatthese systems of giant planets are complete and that their orbits arewell-determined. Assuming the giant planets formed and migrated quickly, thenterrestrial planets may form from a second generation of planetesimals. In eachcase, Moon- to Mars-sized planetary embryos are placed in between the giantplanets and evolved for 100 Myr. We find that planets form relatively easily in55 Cnc, with masses up to 0.6 Earth masses and in some cases substantial watercontents and orbits in the habitable zone. HD 38529 is likely to support anasteroid belt but no terrestrial planets of significant mass. No terrestrialplanets form in HD 37124 and HD 74156, although in some cases 1-2 lone embryossurvive for 100 Myr. If migration occurred later, depleting the planetesimaldisk, then massive terrestrial planets are unlikely to form in any of thesesystems.
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机译：最近的结果表明，许多已知的太阳系外行星系统都包含对地球质量和土星质量都稳定的区域。在此，我们模拟了四个行星系统中的陆地行星的形成-55 Cancri，HD 38529，HD 37124，和HD 74156-假设这些巨型行星系统是完整的并且其轨道是确定的。假设巨型行星迅速形成并迁移，那么第二代小行星可能会形成地行星。在每种情况下，月球到火星大小的行星胚胎都放置在巨行星之间，并进化出100玛尔。我们发现，在55 Cnc时，行星的形成相对容易，质量可达0.6地球质量，在某些情况下，可居住区域的水含量和轨道也很大。 HD 38529可能支持小行星带，但没有质量很大的地球行星。 HD 37124和HD 74156中没有地行星形成，尽管在某些情况下1-2个孤儿胚胎存活100 Myr。如果后来发生迁移，耗尽了行星盘，那么在这些系统中的任何一个都不太可能形成巨大的地球行星。
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