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Tumbling asteroids |
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| Authors: | P Pravec AW Harris P Kušnirák CW Hergenrother MD Hicks YuN Krugly MC Nolan M Kaasalainen P Brown JV Lambert S Foglia |
| Institution: | a Astronomical Institute, Academy of Sciences of the Czech Republic, Fri?ova 1, CZ-25165 Ond?ejov, Czech Republic b Space Science Institute, Boulder, CO 80301, USA c Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA d DLR Institute of Space Sensor Technology and Planetary Exploration, Rutherfordstr. 2, D-12489 Berlin, Germany e Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA f Physics Department, University of Rome “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Rome, Italy g Campo Catino Observatory, Guarcino, I-03016, Italy h Institute of Astronomy of Kharkiv National University, Sumska Str. 35, Kharkiv 61022, Ukraine i Arecibo Observatory, National Astronomy and Ionosphere Center, PR 00612, USA j Department of Mathematics/Rolf Nevanlinna Institute, University of Helsinki, PO Box 4, FIN-00014, Finland k Modra Observatory, Astronomical Institute, FMFI Comenius University, Bratislava, Slovak Republic l Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7, Canada m Alfred University, 1 Saxon Drive, Alfred, NY 14802, USA n Air Force Maui Optical and Supercomputing Facility, Kihei, HI 96753, USA o Blackberry Observatory, 1927 Fairview Dr., Port Allen, LA 70767, USA p Serafino Zani Observatory, Lumezzane, I-25065, Italy |
| Abstract: | We present both a review of earlier data and new results on non-principal axis rotators (tumblers) among asteroids. Among new tumblers found, the best data we have are for 2002 TD60, 2000 WL107, and (54789) 2001 MZ7—each of them shows a lightcurve with two frequencies (full terms with linear combinations of the two frequencies are present in the lightcurve). For 2002 TD60, we have constructed a physical model of the NPA rotation. Other recent objects which have been found to be likely tumblers based on their lightcurves that do not fit with a single periodicity are 2002 NY40, (16067) 1999 RH27, and (5645) 1990 SP. We have done a statistical analysis of the present sample of the population of NPA rotators. It appears that most asteroids larger than ∼0.4 km with estimated damping timescales (Harris, 1994, Icarus 107, 209) of 4.5 byr and longer are NPA rotators. The statistic of two short-period tumblers (D=0.04 and 0.4 km) with non-zero tensile strength suggests that for them the quantity μQ/T, where μ is the mechanical rigidity, Q is the elastic dissipation factor, and T is a spin excitation age (i.e., a time elapsed since the last significant spin excitation event), is greater by two to four orders of magnitude than the larger, likely rubble-pile tumblers. Among observational conditions and selection effects affecting detections of NPA rotations, there is a bias against detection of low-amplitude (small elongation) tumblers. |
| Keywords: | Asteroids Excited rotation Photometry |
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