Rotation Rates of Very Small Near-Earth Asteroids
Abstract
Currently there exists only limited data on physical properties such as rotation rate for the very smallest Near-Earth Asteroids (NEAs) being discovered. The spin period of an asteroid can imply important information about its internal composition (via deduction of strength boundary limits) and degree of fracture, and thereby its collisional history. Our objective is to gather the data needed to test current theories of the relationship between spin limits and overall strength.
We report on a dataset of 38 lightcurves of NEAs collected at the Magdalena Ridge Observatory's (MRO) 2.4-meter telescope, analyzed to obtain rotation rates. The majority of the objects targeted were less than about 200 meters in diameter, where existing data are sparse. These small bodies have exhibited a range of spin rates, from slow ( 8 hours) to very fast (less than a minute). A lightcurve taken of NEA 2010 JL88 (estimated to be 18 meters in diameter) on May 17, 2010, revealed a rotation period of 24.5 seconds, making this object the fastest natural rotator discovered to date. Further, we obtained a lightcurve of asteroid 2009 BF2 ( 27 meters in diameter) on January 17, 2009, and its rotation period was derived to be 58 seconds (the third fastest rotator discovered). We also found 2 NEAs that appear to be tumbling, indicating a recent collisional event. Although a more robust statistical sample of spin rates in this small size regime is still desired, we are making progress toward a better understanding of the physical processes at work as our observational survey of the Near-Earth zone continues. This research is funded through NASA's NEOO program and NSF's Planetary Astronomy program.- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #42
- Pub Date:
- October 2010
- Bibcode:
- 2010DPS....42.6003R