Literature Survey extrasolar planets

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Literature Survey extra-solar planets

• Presented by
• Li, Shu-lin

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1. Planetary formation
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Hybrid mechanisms for gas/ice giant planet
formation

• Basis for mechanism
• The gas drag-induced migration leads to grain
  pileup. Then the particle surface density is
  increased sufficiently high to induce particle
  layer gravitational instability
• The effects of the grain migration on the planet
  formation
• Solid enhancement by the water ice condensation
  for rgt3Au is included

T. Currie
astro-ph/
0409730
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• Results

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Formation of giant planets in disks with
different metallicities

• Motivated by the observed relatively higher
  metallicities of the planet-bearing stars
• Two component fluid model of the disks
• Assumptions
• Particles at the same distance from the star have
  the same diameter
• 100 efficiency of coagulation
• Migration of the planets is not included

K. Kornet et al.

astro-ph/0410112
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• Results
• The rate of planet occurrence as a function of
  the disk metallicity

• Pp is an increasing function of Z
• Giant planet form more easily in less viscous
  disks

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Statistical properties of exoplanets IV. The
period-eccentricity relations of exoplanets and
of binary stars

• Purpose
• to investigate if the properties of exoplanets
  may be considered as an extrapolation of the
  properties of binaries in the range of very low
  mass ratios
• Sample
• 89 spectroscopic binaries found in the solar
  neighborhood or in open clusters with Plt10yr
• 72 exoplanets orbiting main-sequence stars with
  Plt2200 days.

J. L. Halbwachs et al.
astro-ph/0410732
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• Tidal effects
• The (Psre) plane provides a way to explore the
  transition from circularized orbits to orbits
  unaffected by tidal effects .
• Psr P(1-e2)3/2
• The maximum eccentricity with which the system is
  unaffected by tides
• eMax(1-(Pcutoff/P)2/3)1/2

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• Comparisons
• The period-eccentricity diagram

• Circles planets
• Squares SB with qlt0.8
• Dotted line eMax when Pcutoff10 days
• Solid line median eccentricity of the planets
• Dashed line median eccentricity of the SBs

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• The intrinsic distribution of eccentricities

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• Results
• The tidal circularization occurs rapidly for the
  planetary system, while it will process a long
  time after the formation of the binary system
• Beyond the circularization limit, the
  eccentricity of the orbits of planets are
  significantly smaller than those of binary orbits
• Exoplanets and binaries are two different classes
  of objects from the point of view of their
  formation

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Final stages of planet formation

• Investigation of how oligarchic growth of
  planetary formation ends and what happens after
  that
• The conditions at the end of oligarchy
• Compute the competition between the dynamical
  friction from the small bodies and the mutual
  stirring of the big bodies
• The regularization of the orbits of the big
  bodies and the clean up of the small bodies

P. Goldreich et al.
ApJ, 614497,2004
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• Conclusions
• The number and orbital spacing of the planets are
  resulted from an evolution toward stability
  against large-scale chaotic perturbations
• Accretion during oligarchic probably lasted for
  less than 105yr in the inner planet system and
  less than 107yr in the outer planet system
• The timescale for establishing the final
  configuration of planetary orbits was much
  shorter in the inner planet system than that in
  the outer planet system.
• Mechanisms of the cleanup of small bodies are
  different between the inner and outer planet
  system

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The formation of free-floating brown dwarves and
planetary-mass objects by photo-erosion of
prestellar cores

• Exploration of the possibility that the low mass
  objects are formed from pre-existing prestellar
  cores which are eroded by the ambient ionizing
  radiation field.
• Three evolutionary phases
• Set up of the ionization
• a compression wave impinges on the center
  of the proto-star
• the outward expansion wave encounters the
  inward ionization front
• the ionization front encounters material
  which can not be unbound

A. P. Whitworth et al.
astro-ph/0408522
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• Final mass
• M3
• Where aI isothermal sound speed in the neutral
  gas of the core
• rate of emission of Lyman
  continuum photos from the OB stars
• n0 number-density of protons in the
  HII region surrounding the core

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• Conclusions
• The formation of low-mass objects by this
  mechanism is efficient
• The intermediate-mass proto-stars which have
  formed in the vicinity of a group of OB stars
  must have been well on the way to formation
  before the setup of ionization

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2. Disk
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Attenuation of millimeter emission from
circum-stellar disks induced by the rapid dust
accretion

• Observation
• About 50 of classical T Tauri stars (CTTSs) emit
  detectable millimeter continuum
• A notable feature of the millimeter emission is
  the evolution of the spectral index from 2 to 1
• Numerical Calculation
• Based on the assumption that ßlt1 indicates the
  dust grains have grown to gt1mm
• Focused on the largest grains of 1mm

Taku Rakeuchi D. N. C. Lin
astro-ph/0410095
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• Low viscosity models (a10-3)
• Density profile

• Dashed lines
• ?gas
• Solid lines
• ?dustx100

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• Evolution of dust thermal emission at ?1.3mm

• Symbols observations
• Dotted line detection limit
• Solid lines faced on disks ( i0o)
• Dashed lines inclined disks ( i60o)
• A(s/1mm)(?p/1g cm-3)

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• Constraint on the dust growth time
• Growth of millimeter sized grains to centimeter
  size takes more than 106 yr
• Millimeter sized grains are continuously
  replenished

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Type I migration in a non-isothermal
proto-planetary disk

• Analyze the effect of local disk temperature
  variation on type I migration rates of planets
• Improvements compared with previous work
• Three-dimensional protoplanetary disk
• Non-isothermal, i.e. vertical temperature
  variation is considered

HH. J. Condell D. D. Sasselov
astro-ph/0410550
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• Main results
• Calculated total net torques

• Solid lines unperturbed model disk
• Dotted lines isothermal disk
• Dashed lines model disks with planet

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• Scaled torque density versus z at 1 Au (upper
  panel )
• and the temperature gradient (lower panel)

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• Migration rates scaled by the planet mass

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• Conclusions
• Including the vertical thickness of the disk
  results in a decrease in the Type I migration
  rate by a factor of 2 from the 2-D disk
• Vertical temperature variation has only a modest
  effect on migration effect
• The temperature perturbation resulting form
  shadowing and illumination at the disk surface
  can further decrease the migration rate by a
  factor of 2

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3. New observation
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High-resolution spectroscopy of the transiting
planet host star TrES-1

• Report on the spectroscopic determination of the
  stellar parameter and chemical abundances for
  TrES-1 host star
• TrES-1 is the second transiting planet orbiting a
  star bright enough to allow for follow-up
  analyses (after HD209458b)
• Spectroscopic observations obtained by the HIRES
  spectrograph on Keck I telescope and HRS
  spectrograph on HET

A. Sozzetti et al.

astro-ph/0410483
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• Stellar parameters
• Teff525075 K (spectroscopy)
• 520692 K (photometry)
• Log g4.60.2 (spectroscopy)
• Fe/H0.000.09 (spectroscopy)
• Age 2.51.5 Gyr (CaII H and K lines)
• Mass 0.89 0.05 Msun (stellar model)
• Radius 0.83 0.05 Rsun (stellar model)

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• Planetary parameter
• MP0.760.05MJ
• (e0.0 a0.0393 Au P3.03 days)
• Provide a good example to investigate the
  theoretical evolutionary models of irradiated
  giant planets

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The End Thank you!