Zodiacal Cloud: The Local Circumstellar Disk

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Zodiacal Cloud: The Local Circumstellar Disk. Sumita Jayaraman. Why do we study the Zodiacal Cloud?. For the Solar System. Yields information on the formation and evolution of the interplanetary dust disk in our Solar System. For Exo-zodi Disks and Planetary Systems.
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Zodiacal Cloud: The Local Circumstellar DiskSumita JayaramanWhy do we study the Zodiacal Cloud?For the Solar System Yields information on the formation and evolution of the interplanetary dust disk in our Solar System. For Exo-zodi Disks and Planetary SystemsDirect application to the structure of exo- zodi disks and planetary detection.ContentsStructures in the zodiacal cloud
  • Earth’s Resonant Ring
  • Dynamical Asymmetries
  • Dust Bands
  • Structures in Exo-zodiacal disksContentsStructures in the zodiacal cloud
  • Earth’s Resonant Ring
  • Dynamical Asymmetries
  • Dust Bands
  • Structures in Exo-zodiacal disksZodiacal Peak-Flux Variation (COBE-DIRBE)Average Trailing: 70.26 MJ/SrAverage Leading: 68.5 MJy/SrRing Flux : 1.7 MJy/Sr (~2.5%)Resonant Trapping of Dust ParticlesResonance Capture Probability vs Particle SizeEarth’s Resonant Ring ModelSpitzer’s Orbit SunAll-Sky View of RingTrailingLeadingAt Spitzer Launch……After 2 yearsEstimated Ring Flux: ~ 5.5 MJy/Sr (8% of Zody)Resonant Ring Obs. 25μm (COBE-DIRBE)TrailingLeading(Reach et al., 1995)All Sky Model for Extended Spitzer MissionAt LaunchYear 1Year 2Year 3Year 4Year 5Goals of the Spitzer Project
  • Track measurements of the Earth’s Resonant Ring as Spitzer traverses it.
  • Monitor variations in the Ecliptic Pole flux.
  • Measure the absolutely calibrated zodiacal flux and estimate background radiation levels during the mission.
  • Obtain very high resolution images of the asteroidal dust bands.
  • Spitzer Zodical Obs.Spitzer Project: Planned ObsTrailingLeadingIRAC North Ecliptic Pole Flux2004IRAC North Ecliptic Pole Flux20042005IRAC North Ecliptic Pole Flux200420052006MIPS North Ecliptic Pole Flux200420052006Ring: Model vs ObservationsNext Steps
  • Analysis of Ecliptic Plane Observations (predicted increase in ring flux from 2.5%(1.7 MJy/Sr) of zody to 8% (5.5 MJy/Sr) of zody)
  • Multiple Wavelength observations (3.6 and 70 microns) from IRAC, MIPS as well as IRS Peak-up mode.
  • Science Questions
  • What is number density of particles in the ring?
  • What is the background number density required to produce the flux variations?
  • What is the efficiency of capture into resonance by an Earth-mass planet?
  • How do we distinguish a feature like trailing dust cloud in ring from the planetary perturber in an exozodiacal disk?
  • ContentsStructures in the zodiacal cloud
  • Earth’s Resonant Ring
  • Dynamical Asymmetries
  • Dust Bands
  • Structures in Exo-zodiacal disksDynamical Asymmetries in the Zodiacal cloud
  • Off-center shift of the zodiacal cloud shown by the pole observations.
  • Warps in the cloud due to the inclination and shift measured by the variations in peak flux.
  • Sun-Centered CloudZodiacal CenterEarth OrbitSunEarth AphelionOff-Center CloudZodiacal CenterEarth OrbitSunEarth AphelionEvidence for an off-center cloudInclination of the cloudZodiacal Peak-Flux Variation (COBE-DIRBE)Ring Flux : 1.7 MJy/Sr (~2.5%)Zodiacal Peak-Flux Variationwithout the RingZodiacal Peak-Flux Variationdue to Earth’s eccentricityWarps in the Zodiacal cloudContentsStructures in the zodiacal cloud
  • Earth’s Resonant Ring
  • Dynamical Asymmetries
  • Dust Bands
  • Structures in Exo-Zodiacal disksAsteroidal Dust BandsScanContentsStructures in the zodiacal cloud
  • Earth’s Resonant Ring
  • Dynamical Asymmetries
  • Dust Bands
  • Structures in Exo-zodiacal disksDynamical Effects in Circumstellar Disks
  • Resonant trapping – determined by the number and co-rotation of the clumps
  • Recent planetesimal collisions in the disk – young dust bands
  • Planetary perturbations on the disk due to one or more planets causing an inclined and off-center disk.
  • Planetary Signatures in Observed Disks
  • Resonant Rings caused by larger Planets - ε Eridani
  • Off-center disk – HR4796A
  • Gaps in the disk due to Resonant Trapping and scattering due to Large Planet – β Pictoris ?
  • Warps in the disk due to planetary perturbations - β Pictoris.
  • Bands due to stochastic collisions.
  • What do the structures tell us?
  • Location of the planet(s), eccentricity of the orbit
  • Mass of the planet(s)
  • Size of the dust particles (lower limits)
  • ε Eridani(Quillen & Thornedike, 2002)e = 0.3M = 10- 4 MSunA = 40 A.U.HR 4796A (Wyatt et al. 2002)Flux Asymmetry ~ 5% Estimate of Planet Mass > 10 Mass of Earth with e >0.02Challenges in Planetary Detection in Disks
  • Young disks have dust and gas
  • Structures observed in images do not provide unique solutions for planetary masses or location
  • Source of dust is uncertain – especially for disks with small dust grains.
  • Related Search
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