Spectroscopy of Icy Planetoids

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Spectroscopy of Icy Planetoids
Kristina Barkume Caltech

• Collaborators Mike Brown, Henry Roe, Emily
  Schaller

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Survey of the Icy Planetoids
Data Set

• KBOs with absolute magnitude lt 4.7 (i.e.
  diameter gt 500 km)
• 40 objects

Observations

• 1.0-2.4 micron spectra from Keck Telescopes
• .36-.9 micron spectra from Palomar 200
• Albedos with Spitzer Space Telescope
• Search for moons with HST Keck AO

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Near Infrared Spectrum of 2003 EL61
Relative Reflectance
Microns
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Near Infrared Spectrum of 2003 EL61
Relative Reflectance
A 1- R(2.0)/R(1.7)
A554
Microns
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NIR Spectrum of S/2005 (2003 EL61) 1
Relative Reflectance
A8711
Microns
Barkume, et al. 2006
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NIR spectrum of 2002 TX300
Relative Reflectance
A6312
Microns
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NIR spectrum of 2003 OP32
Relative Reflectance
A7511
Microns
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NIR Spectrum of 2003 AZ84
Relative Reflectance
Microns
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NIR Spectrum of 2003 AZ84
Relative Reflectance
Water Ice Model
A2220
Microns
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TNOs with No Water Ice Absorption
2002 TC302
2002 UX25
Relative Reflectance
2002 AW197
2003 VS2
A0
Microns
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Water Ice Absorption
A 1- R(2.0)/R(1.7)
(2003 EL61)1 2003OP32 1996TO66 2002TX300 Charon 20
03EL61 Quaoar Orcus 2003AZ84 Varuna 2002VE95 1999D
E9 Ixion Huya 1999TD10 2003VS2 2002KX14 2001UR163
1996TP66 2000PE30 2003FX128 1999TC36 2002TC302 200
OJ67 2002AW197 2002UX25 1993SC 1996TL66 1996GQ21 1
997CS29 K40804A 1998WH24 1999RZ253 2000GN171
Absorption
Reference Barucci, et al 2006, references
therein
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Crystalline Water Ice
A 1- R(2.0)/R(1.7)
?
(2003 EL61)1 2003OP32 1996TO66 2002TX300 Charon 20
03EL61 Quaoar Orcus 2003AZ84 Varuna 2002VE95 1999D
E9 Ixion Huya 1999TD10 2003VS2 2002KX14 2001UR163
1996TP66 2000PE30 2003FX128 1999TC36 2002TC302 200
OJ67 2002AW197 2002UX25 1993SC 1996TL66 1996GQ21 1
997CS29 K40804A 1998WH24 1999RZ253 2000GN171
Absorption
Reference Barucci, et al 2006, references
therein
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Near Infrared Spectral Types
Methane
Water ice
Featureless
65
35
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Absorption and Absolute Magnitude
Absorption
Absolute Magnitude
http//cfa-www.harvard.edu/iau/lists/TNOs.html
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Visible Colors of KBOs
Absorption
Red
Blue
VRI Color Gradient (1/ 100 nm)
References 2,3,4
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Absorption and Eccentricity
Eccentricity
Semi-major Axis
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Absorption and Inclination
Inclination
Semi-major Axis
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Near Infrared Spectral Types
Methane
Very Water Icy
Water ice
Featureless
H20 moons
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Processes
Cryovolcanism
Continuum Population Possible Very Water Icy
Population Possible
Continuum Population Possible Very Water Icy
Population Unlikely
Giant Impact
Differentiation
Continuum Population Unlikely Very Water Icy
Population Very likely for some
Continuum Population Unlikely Very Water Icy
Population Possible
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Wild Speculations
Features of Families

• Similar orbital elements composition
• Fragments can be similar in size to impact

But consider.

• Its the proper orbital elements that matter
• dynamical life times are unknown

However, families may exist in the Kuiper Belt if
Dynamical Lifetimes allow
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Final Thoughts

• We find evidence of water of 1/3 of observed
  objects
• We see indications that water ice objects are in
  two populations based on their physical features
• Very Water Icy
• Continuous distribution
• For the Very Water Icy Objects
• The TNOs have similar orbital elements
• Grey-Bluish Visible Colors

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References
Infrared Spectra 1. Barucci, et al (2006),
references therein

• Colors
• Hainaut Delsanti (2002)
• Fornasier, et al. (2004)
• 4. http//www.physics.nau.edu/tegler/research/sur
  vey.htm

Rotational Periods 5. Lacerda Luu. (2006)
reference therein
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Angular Momentum of Icy TNOs
Object Rotation Moons
2003 EL61 1996 TO66 2002 TX300 2003 OP32 3.9 hrs 7.9 hrs 16.24 NA 2 0 0 NA
Reference Lacerda Luu. (2006) reference therein
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Rotation
Absorption
Rotation (hours)
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Distribution of Water Ice
Absorption
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NIR spectrum of 2003 OP32
Relative Reflectance
Microns