1. Unusual Lightcurves in the Vesta Family of Asteroids William H. Ryan (NM Tech/MRO) Eileen V. Ryan (NM Tech/MRO) Carlos Martinez (UNM) 36 th Division of Planetary Sciences Meeting Louisville, KY November 12, 2004

2. 36 th Division of Planetary Sciences Meeting Project Overview: 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) Family Members observed –26 Asteroids Observed –15 Periods Derived –8 Multi-apparition lightcurves Facilities used: 1.8 m VATT (VORG); 1m CTIO (NOAO); 0.35 m Etscorn (NM Tech)

3. Louisville, KY November 12, 2004 36 th Division of Planetary Sciences Meeting 2511 Patterson

4. Louisville, KY November 12, 2004 36 th Division of Planetary Sciences Meeting 3782 Celle - 5 Jan 2003

5. Louisville, KY November 12, 2004 36 th Division of Planetary Sciences Meeting January 2003 (Residuals)

6. Louisville, KY November 12, 2004 36 th Division of Planetary Sciences Meeting 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 = 36.57  0.03 hours Semi-major axis/primary diameter = 3.3 .2 Mean density = 2.2 .4 g/cm 3 (Basalt ~ 2.9 g/cm 3 HED Meteorites ~ 2.9-3.3 g/cm 3 ) (Ryan, Ryan, and Martinez, 2004)

7. Louisville, KY November 12, 2004 36 th Division of Planetary Sciences Meeting 3703 Volkonskaya - Dec 2000

8. Louisville, KY November 12, 2004 36 th Division of Planetary Sciences Meeting 3703 Volkonskaya - Aug. 2003 Additional Volkonskaya data thanks to Fumi Yoshida (NAOJ), Bisei Staff, Shigeru Takahashi (Lulin), Mansur Ibrahimov (Maidanak)

9. Louisville, KY November 12, 2004 36 th Division of Planetary Sciences Meeting 3155 Lee - Jan 2000

10. Louisville, KY November 12, 2004 36 th Division of Planetary Sciences Meeting 3155 Lee - Mar 2004

11. Louisville, KY November 12, 2004 36 th Division of Planetary Sciences Meeting Conclusions One definitive binary and one highly probable binary in the Vesta family. At least 2 other “unusual” objects. These discoveries a double-edged sword: exciting, but have slowed the overall survey. Expectation is that a comprehensive physical characterization of this family will assist in refining efforts to model large-scale collisions in the solar system.