Binaries in the Vesta Family of Asteroids

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Binaries in the Vesta Family of Asteroids

• William H. Ryan (NM Tech/MRO)
• Eileen V. Ryan (NM Tech/MRO)
• Carlos Martinez (UNM)

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Project Background

• Multi-apparition Photometric study of Vesta
  family (asteroids dynamically and chemically
  linked to Vesta)
• Motivation Difficulty modeling Vesta family
  (and other families) formation from cratering
  impact event
• (Melosh and E. Ryan, 1997 Asphaug 1997)
• Other Student Observers during lifetime of
  project
• Amanda Roybal
• Lawrence Tafoya
• Lacey Stewart
• Facility used 1.8 m Vatican Advanced Technology
  Telescope (thanks to VORG, Matt Nelson, Randy
  Swift)

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September 2001
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December 2002
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December 2002
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December 2002
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January 2003
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January 2003 Composite
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January 2003 (Residuals)
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January 2003 (Late Jan. residuals)
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January 2003 (Intensity Subtraction)
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Analysis of 5 Jan. 2003 Event
Dttot
Dm
Dtplat
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Analysis of 5 Jan. 2003 Event
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Analysis of 5 Jan. 2003 Event
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Summary 3782 Celle Binary System

• Secondary/Primary diameters 0.43 ? 0.01
• Primary Diameter 6 km (H 12.5)
• Primary Rotational Period 3.84 hours
• Orbital Period 36.57 ? 0.03 hours
• Semi-major axis/primary diameter 3.4 ? 0.2
• Mean density 2.3 ? 0.4 g/cm3
• (Basalt 2.9 g/cm3 HED Meteorites
  2.9-3.3 g/cm3)

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Binary primaries Spin vs. Size
(Courtesy Petr Pravec)
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Binary primaries Amplitude vs. Spin
(Courtesy Petr Pravec)
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Binary Asteroids
(Courtesy Petr Pravec)
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Types of Asteroid Satellites
(Courtesy Dan Durda, SWRI)
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Binary Formation Mechanisms

• Vesta impact relic - EEB (Durda, et. al., 2003)
• Tidal Disruption (Bottke and Melosh, 1996)
• Rotational Fragmentation (Giblin, Petit, and
• Farinella, 1998)
• Secondary Impact??
• Observe again next apparition (2004) at different
  geometry to confirm/refine model parameters