Binaries in the Vesta Family of Asteroids William H. Ryan (NM Tech/MRO) Eileen V. Ryan (NM Tech/MRO) Carlos Martinez (UNM)

Socorro, NM October 3, th Annual New Mexico Symposium 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)

Socorro, NM October 3, th Annual New Mexico Symposium September 2001

Socorro, NM October 3, th Annual New Mexico Symposium December 2002

Socorro, NM October 3, th Annual New Mexico Symposium December 2002

Socorro, NM October 3, th Annual New Mexico Symposium December 2002

Socorro, NM October 3, th Annual New Mexico Symposium January 2003

Socorro, NM October 3, th Annual New Mexico Symposium January 2003: Composite

Socorro, NM October 3, th Annual New Mexico Symposium January 2003 (Residuals)

Socorro, NM October 3, th Annual New Mexico Symposium January 2003 (Late Jan. residuals)

Socorro, NM October 3, th Annual New Mexico Symposium January 2003 (Intensity Subtraction)

Socorro, NM October 3, th Annual New Mexico Symposium Analysis of 5 Jan Event mm  t plat  t tot

Socorro, NM October 3, th Annual New Mexico Symposium Analysis of 5 Jan Event dpdp dsds a 

Socorro, NM October 3, th Annual New Mexico Symposium Analysis of 5 Jan Event  dpdp dsds a

Socorro, NM October 3, th Annual New Mexico Symposium Summary: 3782 Celle Binary System Secondary/Primary diameters = 0. .01 Primary Diameter ~ 6 km (H ~ 12.5) Primary Rotational Period = 3.84 hours Orbital Period =  0.03 hours Semi-major axis/primary diameter = 3.4 .2 Mean density = 2.3 .4 g/cm 3 (Basalt ~ 2.9 g/cm 3 HED Meteorites ~ g/cm 3 )

Socorro, NM October 3, th Annual New Mexico Symposium Binary primaries – Spin vs. Size (Courtesy Petr Pravec)

Socorro, NM October 3, th Annual New Mexico Symposium Binary primaries – Amplitude vs. Spin (Courtesy Petr Pravec)

Socorro, NM October 3, th Annual New Mexico Symposium Binary Asteroids (Courtesy Petr Pravec)

Socorro, NM October 3, th Annual New Mexico Symposium Types of Asteroid Satellites (Courtesy Dan Durda, SWRI)

Socorro, NM October 3, th Annual New Mexico Symposium 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