EDP Sciences
Free access
Volume 461, Number 3, January III 2007
Page(s) 1195 - 1208
Section Planets and planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:20066171

A&A 461, 1195-1208 (2007)
DOI: 10.1051/0004-6361:20066171

On the formation of terrestrial planets in hot-Jupiter systems

M. J. Fogg and R. P. Nelson

Astronomy Unit, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
    e-mail: [M.J.Fogg;R.P.Nelson]@qmul.ac.uk

(Received 3 August 2006 / Accepted 9 October 2006)

Context.There are numerous extrasolar giant planets which orbit close to their central stars. These "hot-Jupiters" probably formed in the outer, cooler regions of their protoplanetary disks, and migrated inward to $\sim $0.1 AU. Since these giant planets must have migrated through their inner systems at an early time, it is uncertain whether they could have formed or retained terrestrial planets.
Aims.We present a series of calculations aimed at examining how an inner system of planetesimals/protoplanets, undergoing terrestrial planet formation, evolves under the influence of a giant planet undergoing inward type II migration through the region bounded between 5-0.1 AU.
Methods.We have previously simulated the effect of gas giant planet migration on an inner system protoplanet/planetesimal disk using a N-body code which included gas drag and a prescribed migration rate. We update our calculations here with an improved model that incorporates a viscously evolving gas disk, annular gap and inner-cavity formation due to the gravitational field of the giant planet, and self-consistent evolution of the giant's orbit.
Results.We find that $\gtrsim$60% of the solids disk survives by being scattered by the giant planet into external orbits. Planetesimals are scattered outward almost as efficiently as protoplanets, resulting in the regeneration of a solids disk where dynamical friction is strong and terrestrial planet formation is able to resume. A simulation that was extended for a few Myr after the migration of the giant planet halted at 0.1 AU, resulted in an apparently stable planet of $\sim $ $m_{\oplus}$ forming in the habitable zone. Migration-induced mixing of volatile-rich material from beyond the "snowline" into the inner disk regions means that terrestrial planets that form there are likely to be water-rich.
Conclusions.We predict that hot-Jupiter systems are likely to harbor water-abundant terrestrial planets in their habitable zones. These planets may be detected by future planet search missions.

Key words: planets and satellites: formation -- methods: N-body simulations -- astrobiology

© ESO 2007