Asteroid 2 Pallas Physical Properties from Near-Infrared - - PowerPoint PPT Presentation

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Asteroid 2 Pallas Physical Properties from Near-Infrared - - PowerPoint PPT Presentation

Feb 23, 2024 271 likes •507 views

Pallas Observations Size & Shape Surface Analysis Summary Asteroid 2 Pallas Physical Properties from Near-Infrared High-Angular Resolution Imagery B . Carry 1 , 2 M . Kaasalainen 3 C . Dumas 1 J . Berthier 4 W . Merline 5 1 European

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Pallas Observations Size & Shape Surface Analysis Summary

Asteroid 2 Pallas Physical Properties from Near-Infrared High-Angular Resolution Imagery

B.Carry1,2 M.Kaasalainen3 C.Dumas1 J.Berthier4 W.Merline5 A.Conrad6 T.Fusco7 D.Hestroffer4 M.Fulchignoni2 S.Erard2

1European Southern Observatory 2LESIA,Observatoire de Paris 3University of Helsinki 4IMCCE, Observatoire de Paris 5Southwest Research Institute 6Keck Observatory 7ONERA

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Pallas Observations Size & Shape Surface Analysis Summary

Asteroid 2 Pallas

⊲ Second Asteroid Discovered

  • H. Olbers, 1802

⊲ Unusual among Big Asteroids

  • High Inclinaison
  • High Excentricity

⊲ Almost NOT studied

  • Only Mass Measurement since 1996
  • Half Studies Joint with Ceres
  • “Unloved Little Brother”
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Pallas Observations Size & Shape Surface Analysis Summary

Asteroid 2 Pallas

⊲ Second Asteroid Discovered

  • H. Olbers, 1802

⊲ Unusual among Big Asteroids

  • High Inclinaison
  • High Excentricity

⊲ Almost NOT studied

  • Only Mass Measurement since 1996
  • Half Studies Joint with Ceres
  • “Unloved Little Brother”
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SLIDE 4

Pallas Observations Size & Shape Surface Analysis Summary

Asteroid 2 Pallas

⊲ Second Asteroid Discovered

  • H. Olbers, 1802

⊲ Unusual among Big Asteroids

  • High Inclinaison
  • High Excentricity

⊲ Almost NOT studied

  • Only Mass Measurement since 1996
  • Half Studies Joint with Ceres
  • “Unloved Little Brother”
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SLIDE 5

Pallas Observations Size & Shape Surface Analysis Summary

Asteroid 2 Pallas

⊲ Second Asteroid Discovered

  • H. Olbers, 1802

⊲ Unusual among Big Asteroids

  • High Inclinaison
  • High Excentricity

⊲ Almost NOT studied

  • Only Mass Measurement since 1996
  • Half Studies Joint with Ceres
  • “Unloved Little Brother”
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Pallas Observations Size & Shape Surface Analysis Summary

Asteroid 2 Pallas

bonjour au revoir salut! hmm, relou

2001, Goffin et al., A&A, 365 1996, Mitchell et al., Icarus, 124 1993, Saint-P´ e et al., Icarus, 105 1989, Drummond et al., Icarus, 78

⊲ Second Asteroid Discovered

  • H. Olbers, 1802

⊲ Unusual among Big Asteroids

  • High Inclinaison
  • High Excentricity

⊲ Almost NOT studied

  • Only Mass Measurement since 1996
  • Half Studies Joint with Ceres
  • “Unloved Little Brother”
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Pallas Observations Size & Shape Surface Analysis Summary

Observations

  • Keck II Observatory
  • 2003 opposition
  • φ ∼ .44”
  • 10 m mirror
  • 1/2 hour, 1 night
  • NACO on Yepun/VLT
  • 2005 opposition
  • φ > .44”
  • 8.2 m mirror
  • 4 hours, 5 nights
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Pallas Observations Size & Shape Surface Analysis Summary

Observations

  • Keck II Observatory
  • 2003 opposition
  • φ ∼ .44”
  • 10 m mirror
  • 1/2 hour, 1 night
  • NACO on Yepun/VLT
  • 2005 opposition
  • φ > .44”
  • 8.2 m mirror
  • 4 hours, 5 nights
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Pallas Observations Size & Shape Surface Analysis Summary

Pallas at Near-Infrared Wavelengths

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Pallas Observations Size & Shape Surface Analysis Summary

Edges Detection

Frodo is alive!!!

http://thames.cs.rhul.ac.uk/∼multires/ 2007, Conrad et al., Icarus, in press

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Pallas Observations Size & Shape Surface Analysis Summary

Lightcurve Inversion Model

Is Frodo Here ?

2003, ˇ Durech et al., A&A, 404 2003, Kaasalainen et al., Icarus, 159 2003, Kaasalainen et al., Icarus, 153

  • Many Lightcurves
  • Many Solar Phases

⊲ ONE Sidereal Period ⊲ TWO Pole Solutions ⊲ TWO Shape Models ⊲ CONVEX Shape Models

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Pallas Observations Size & Shape Surface Analysis Summary

Lightcurve Inversion Model

Is Frodo Here ?

2003, ˇ Durech et al., A&A, 404 2003, Kaasalainen et al., Icarus, 159 2003, Kaasalainen et al., Icarus, 153

  • Many Lightcurves
  • Many Solar Phases

⊲ ONE Sidereal Period ⊲ TWO Pole Solutions ⊲ TWO Shape Models ⊲ CONVEX Shape Models

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Pallas Observations Size & Shape Surface Analysis Summary

Lightcurve Inversion Model

Is Frodo Here ?

2003, ˇ Durech et al., A&A, 404 2003, Kaasalainen et al., Icarus, 159 2003, Kaasalainen et al., Icarus, 153

  • Many Lightcurves
  • Many Solar Phases

⊲ ONE Sidereal Period ⊲ TWO Pole Solutions ⊲ TWO Shape Models ⊲ CONVEX Shape Models

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SLIDE 14

Pallas Observations Size & Shape Surface Analysis Summary

Lightcurve Inversion Model

Is Frodo Here ?

2003, ˇ Durech et al., A&A, 404 2003, Kaasalainen et al., Icarus, 159 2003, Kaasalainen et al., Icarus, 153

  • Many Lightcurves
  • Many Solar Phases

⊲ ONE Sidereal Period ⊲ TWO Pole Solutions ⊲ TWO Shape Models ⊲ CONVEX Shape Models

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Pallas Observations Size & Shape Surface Analysis Summary

LC + AO Analysis

2003, Torppa et al., Icarus, 164

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Pallas Observations Size & Shape Surface Analysis Summary

Results

⊲ Unique Pole Solution

  • Ecliptic J2000.0 λ = 34o, β = −11o (±5o)
  • Future Observations Prediction via Ephemeris

⊲ Precise Size Measurement

  • a x b x c = 277 km x 213 km x 208 km
  • 1-σ dispersion: 10 km x 8 km x 8 km
  • ρ ∼ 4500 ± 500 kg.m−3

⊲ More Complex Shape Model

  • Render Better the Global Shape
  • Allows Concavity
  • Allows Surface Mapping

2007?, Carry et al., in prep. 2007, Kaasalainen et al., DPS Meeting 2006, Marchis et al., Icarus, 185

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Pallas Observations Size & Shape Surface Analysis Summary

Surface Mapping

➊ Geometry Election ➋ Region of Interest Definition ➌ Phase Angle Effect Removal ➍ Coordinates Conversion

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Pallas Observations Size & Shape Surface Analysis Summary

Surface Mapping

➊ Geometry Election ➋ Region of Interest Definition ➌ Phase Angle Effect Removal ➍ Coordinates Conversion

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Pallas Observations Size & Shape Surface Analysis Summary

Surface Mapping

➊ Geometry Election ➋ Region of Interest Definition ➌ Phase Angle Effect Removal ➍ Coordinates Conversion

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Pallas Observations Size & Shape Surface Analysis Summary

Surface Mapping

➊ Geometry Election ➋ Region of Interest Definition ➌ Phase Angle Effect Removal ➍ Coordinates Conversion

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Pallas Observations Size & Shape Surface Analysis Summary

Surface Mapping

Here’s Frodo!

2007, Carry et al., A&A, submitted 2006, Li et al., Icarus, 182

➊ Geometry Election ➋ Region of Interest Definition ➌ Phase Angle Effect Removal ➍ Coordinates Conversion

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Pallas Observations Size & Shape Surface Analysis Summary

Surface Mapping

Frodo is

1990, Greeley et al. Planetary Mapping Cambridge University Press

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Pallas Observations Size & Shape Surface Analysis Summary

Summary

⊲ Spin Vector Determination

  • Ephemeris Solution

⊲ Size Measurement & Shape Modelisation

  • Quite far from 285 x 262 x 241, [1989, Drummond et al., Icarus, 78]
  • Density Measurement

⊲ Surface Mapping

  • To be Analyzed...