NOAO >   Observing Info >   Approved Programs >   2010A-0322

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Proposal Information for 2010A-0322


PI: Rachel Stevenson, UCLA, stevenson@ucla.edu
Address: Earth and Space Sciences, 595 Charles Young Drive East, Los Angeles, CA 90095-1567, USA

CoI: David Jewitt, UCLA

Title: The Thermal History of the Themis Family

Abstract: The discovery of a new class of objects, the Main Belt Comets, has confirmed that ice has been preserved within the Main Belt, despite the fact that the snowline long ago migrated outwards to ~ 5 AU. Main Belt Comets are cometary in appearance, with comae and dust tails visible, but are dynamically unremarkable when compared to asteroids within the Main Belt. Three of the four known Main Belt Comets are dynamically linked to the Themis Family - a collisional family of ~ 550 asteroids that was created when a 380 km progenitor catastrophically disrupted approximately 2 Gyr ago. Other Themis Family members are likely to have retained ice deposits and are, thus, potential Main Belt Comets, yet, conversely, hydrated minerals have been detected on one member of the family, asteroid 24 (Themis). The presence of these minerals imply that liquid water was once present on the asteroid, and suggest post-formation heating took place. The preservation of ice within Main Belt Comets suggests that the Themis Family may have once been, and may still be, an important reservoir of ice, while the detection of hydrated minerals on asteroid 24 (Themis) argues for post-formation heating in that region. We will search for hydration features on Themis Family asteroids to constrain the possible thermal evolution of potential Main Belt Comets.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2010A-0322

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