Induced planet formation in stellar clusters - a parameter study of star-disk encounters

Abstract

We present a parameter study of the possibility of tidally triggered disk instability. Using a restricted N-body model which allows for a survey of an extended parameter space, we show that a passing dwarf star with a mass between 0.1 and 1 M_sun can probably induce gravitational instabilities in the pre-planetary solar disk for prograde passages with minimum separations below 80-170 AU for isothermal or adiabatic disks. Inclined and retrograde encounters lead to similar results but require slightly closer passages. Such encounter distances are quite likely in young moderately massive star clusters (Scally & Clarke 2001; Bonnell et al. 2001). The induced gravitational instabilities may lead to enhanced planetesimal formation in the outer regions of the protoplanetary disk, and could therefore be relevant for the existence of Uranus and Neptune, whose formation timescale of about 100 Myr (Wuchterl, Guillot & Lissauer 2000) is inconsistent with the disk lifetimes of about a few Myr according to observational data by Haisch, Lada & Lada (2001). The relatively small gas/solid ratio in Uranus and Neptune can be matched if the perturbing fly-by occurred after early gas depletion of the solar system, i.e. when the solar system was older than about 5 Myr. We also confirm earlier results by Heller (1993) that the observed 7 degree tilt of the solar equatorial plane relative to the ecliptic plane could be the consequence of such a close encounter.

11 pages, 9 figures, using aas_macros.sty. MNRAS, accepted

References in corpus (7)

• Turbulence in Accretion Disks. Vorticity Generation and Angular Momentum Transport via the Global Baroclinic Instability
• Can giant planets form by direct gravitational instability?
• The evolution of gravitationally unstable protoplanetary disks: fragmentation and possible giant planet formation
• Final Stages of Planet Formation
• Fast accretion of small planetesimals by protoplanetary cores
• On the formation time scale and core masses of gas giant planets
• Are galactic disks dynamically influenced by dust?

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• The Jeans Mass as a Fundamental Measure of Self-Gravitating Disc Fragmentation and Initial Fragment Mass
• ALMA Observations of the T Tauri Binary System AS 205: Evidence for Molecular Winds and/or Binary Interactions
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• The dynamical evolution of low-mass hydrogen-burning stars, brown dwarfs and planetary-mass objects formed through disc fragmentation
• A Numerical Study of Brown Dwarf Formation via Encounters of Protostellar Disks
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• DESTINY: Database for the Effects of STellar encounters on dIsks and plaNetary sYstems
• Heterogeneous evolution of the galaxy and the origin of the short-lived nuclides in the early solar system
• On encounter rates in star clusters
• Generation of inclined protoplanetary discs and misaligned planets through mass accretion I: Coplanar secondary discs
• The formation of planets by disc fragmentation