Quantifying orbital migration from exoplanet statistics and host metallicities

Abstract

We investigate how the statistical distribution of extrasolar planets may be combined with knowledge of the host stars' metallicity to yield constraints on the migration histories of gas giant planets. At any radius, planets that barely manage to form around the lowest metallicity stars accrete their envelopes just as the gas disk is being dissipated, so the lower envelope of planets in a plot of metallicity vs semi-major axis defines a sample of non-migratory planets that will have suffered less than average migration subsequent to gap opening. Under the assumption that metallicity largely controls the initial surface density of planetesimals, we use simplified core accretion models to calculate how the minimum metallicity needed for planet formation varies as a function of semi-major axis. Models that do not include core migration prior to gap opening (Type I migration) predict that the critical metallicity is largely flat between the snow line and a semimajor axis of about 6 AU, with a weak dependence on the initial surface density profile of planetesimals. When slow Type I migration is included, the critical metallicity is found to increase steadily from 1-10 AU. Large planet samples, that include planets at modestly greater orbital radii than present surveys, therefore have the potential to quantify the extent of migration in both Type I and Type II regimes.

ApJ, in press

References in corpus (25)

• Disk Frequencies and Lifetimes in Young Clusters
• Towards a Deterministic Model of Planetary Formation I: a Desert in the Mass and Semi Major Axis Distributions of Extra Solar Planets
• Spectroscopic [Fe/H] for 98 extra-solar planet-host stars: Exploring the probability of planet formation
• Planetesimal Formation by Gravitational Instability
• The metal-rich nature of stars with planets
• Disk Accretion Onto High-Mass Planets
• Eccentricity Evolution for Planets in Gaseous Disks
• Models of the in situ formation of detected extrasolar giant planets
• Three-dimensional Calculations of High and Low-mass Planets Embedded in Protoplanetary Discs
• The interaction of planets with a disc with MHD turbulence IV: Migration rates of embedded protoplanets
• Critical Protoplanetary Core Masses in Protoplanetary Disks and the Formation of Short-Period Giant Planets
• Migration and giant planet formation
• On the Snow Line in Dusty Protoplanetary Disks
• Type I Planetary Migration with MHD Turbulence
• Particle Pile-ups and Planetesimal Formation
• Predictions for the frequency and orbital radii of massive extrasolar planets
• Saturation of the corotation resonance in a gaseous disk
• Dispersion in the lifetime and accretion rate of T Tauri discs
• On the formation time scale and core masses of gas giant planets
• Eccentricity Evolution of Resonant Migrating Planets
• Formation of giant planets in disks with different metallicities
• On the Possible Correlation Between the Orbital Periods of Extra-solar Planets and the Metallicity of the Host Stars
• A Minimum-Mass Extrasolar Nebula
• Are beryllium abundances anomalous in stars with giant planets?
• Type I Migration in a Non-Isothermal Protoplanetary Disk

Cited by in corpus (10)

• The Keck Planet Search: Detectability and the Minimum Mass and Orbital Period Distribution of Extrasolar Planets
• The California Planet Survey I. Four New Giant Exoplanets
• The HARPS search for southern extra-solar planets V. A 14 Earth-masses planet orbiting HD 4308
• Confirmation of the Planet Hypothesis for the Long-period Radial Velocity Variations of Beta Geminorum
• The First Planets: the Critical Metallicity for Planet Formation
• The Chemical Compositions of Stars with Planets: A Review
• High-Resolution Spectroscopy of the Planetary Host HD 13189: Highly-Evolved and Metal-Poor
• Connecting planets around horizontal branch stars with known exoplanets
• Detectability of Exoplanetary Transits from Radial Velocity Surveys
• A statistical model for the relation between exoplanets and their host stars