Icarus 177 (2005) 256–263 www.elsevier.com/locate/icarus The formation and habitability of terrestrial planets in the presence of close-in giant planets Sean N. Raymond a,∗ , Thomas Quinn a , Jonathan I. Lunine b a Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA b Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85287, USA Received 29 July 2004; revised 7 March 2005 Available online 28 April 2005 Abstract ‘Hot jupiters,’ giant planets with orbits very close to their parent stars, are thought to form farther away and migrate inward via interactions with a massive gas disk. If a giant planet forms and migrates quickly, the planetesimal population has time to re-generate in the lifetime of the disk and terrestrial planets may form [P.J. Armitage, A reduced efficiency of terrestrial planet formation following giant planet migration, Astrophys. J. 582 (2003) L47–L50]. We present results of simulations of terrestrial planet formation in the presence of hot/warm jupiters, broadly defined as having orbital radii 0.5 AU. We show that terrestrial planets similar to those in the Solar System can form around stars with hot/warm jupiters, and can have water contents equal to or higher than the Earth’s. For small orbital radii of hot jupiters (e.g., 0.15, 0.25 AU)potentially habitable planets can form, but for semi-major axes of 0.5 AU or greater their formation is suppressed. We show that the presence of an outer giant planet such as Jupiter does not enhance the water content of the terrestrial planets, but rather decreases their formation and water delivery timescales. We speculate that asteroid belts may exist interior to the terrestrial planets in systems with close-in giant planets.  2005 Elsevier Inc. All rights reserved. Keywords: Planetary formation; Extrasolar planets; Cosmochemistry; Exobiology 1. Introduction Roughly one-third of the giant planets discovered to date outside the Solar System have orbits within 0.5 astronomical units (AU) of their central stars. 1 These close-in giant plan- ets, also known as “hot/warm jupiters,” 2 are thought to have formed farther out and migrated inward via gravitational torques with a massive gas disk (Lin et al., 1996). If this mi- * Corresponding author. Fax: +1 (206) 685 0403. E-mail addresses: raymond@astro.washington.edu (S.N. Raymond), trq@astro.washington.edu (T. Quinn), jlunine@lpl.arizona.edu (J.I. Lunine). 1 See, e.g., http://www.exoplanets.org. 2 The term “hot jupiter” is generally reserved for planets inside 0.1 AU. The population of giant planets that we are studying have semimajor axes 0.15 AU  a  0.5 AU are better described as “warm jupiters.” For sim- plicity, we refer to all close-in giant planets as hot jupiters. gration occurs within roughly the first million years (Myr) of the disk lifetime, 3 the planetesimal population (the build- ing blocks of terrestrial planets) has time to replenish after being destroyed during migration. However, if migration oc- curs later, planetesimals are destroyed without enough time to re-form, making it impossible for sizable terrestrial plan- ets to form (Armitage, 2003). In some cases, already-formed terrestrial planets may sur- vive the migration of a giant planet through the terrestrial zone. The survival rate of terrestrial planets depends on the rate of migration (faster migration means higher survival rate) and ranges from 15–40% (Mandell and Sigurdsson, 2003). However, most of the surviving planets are on highly 3 The given value of 1 Myr is a average value, which depends on the dust diffusion and planetesimal formation parameters—see Armitage (2003) for more detail. 0019-1035/$ – see front matter  2005 Elsevier Inc. All rights reserved. doi:10.1016/j.icarus.2005.03.008