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P. Pravec, P. Scheirich, P. Kusnirák, L. Sarounová (Astronomical Institute, Academy of Sciences, Czech Republic), S. Mottola, G. Hahn (DLR, Institute of Planetary Research, Berlin, Germany), P. Brown, N. Kaiser, Z. Krzeminski, G. Esquerdo (Dept. of Physics and Astronomy, Univ. of Western Ontario, Canada), A. Galád, S. Gajdos, L. Kornos, J. Világi (Dept. of Astronomy, Physics of the Earth and Meteorology, FMFI UK, Bratislava, Slovakia), A. W. Harris (Space Science Institute), M. D. Hicks (JPL), D. P. Pray (Carbuncle Hill Observatory), B. Warner (Palmer Divide Observatory), W. Holliday (River Oaks Observatory), R. Behrend (Observatoire de Geneve, Switzerland), D. R. DeGraff (Alfred University), D. Tholen (IfA, University of Hawai'i), R. Whiteley, S. Larson (Univ. of Arizona, LPL), A. Grauer (Dept. of Physics and Astronomy, U. Arkansas at Little Rock), G. M. Funkhouser, B. L. Knight, S. M. Slivan (Dept. of Astronomy, Whitin Observatory, Wellesley College), A. Oksanen (Nyrola Observatory, Jyvaskylan Sirius, Finland), D. Higgins (Hunters Hill Observatory, Australia), F. P. Velichko (Inst. of Astronomy of Kharkiv National University, Ukraine), G. Masi (Physics Dept., University of Rome ``Tor Vergata'', Italy), W. R. Cooney, Jr. (Blackberry Observatory), K. Kirsch, R. Dyvig (Badlands Observatory), R. Stephens (Santana Observatory), L. Snyder (MacLean/Tahoe Observatories)
We revisited and re-analysed photometric data obtained for 16 binary near-Earth asteroids (14 of them are certain detections, either from photometry or from radar, two are serious suspects). We present an overview of general properties of the binary NEA population. Satellite sizes of all but one of the systems are in the range 0.2 to 0.5 primary's diameter, with the upper limit appearing significant. Primary diameters span most of the size range of rubble-pile near-Earth asteroids, i.e., from 0.2 km up to a few km. All but one system are asynchronous systems, with the primary rotating much faster than the mutual orbital period - most of the reliably estimated primary rotation periods are confined to the narrow range 2.2--2.8 h; the two outliers have primary periods of 3.594 h and 13.89 h. Orbital periods distribution shows a significant lower limit of ~12 h while there is no obvious upper limit. Secondary rotations appear mostly (but not generally) synchronized with the mutual orbital motions. While primaries show lightcurves with low amplitudes indicating that they have roughly spheroidal shapes with low equatorial elongations, secondary lightcurves suggest that some of them have more elongated shapes. We will investigate observational selection effects and biases present in the observed sample in order to debias the observed parameters distributions. The distributions will be discussed and compared with theoretical predictions. An updated estimate of the fraction of binary systems among near-Earth asteroids will also be derived.
The work at Ondrejov was supported by the Grant Agency of the Czech Academy of Sciences, Grant A3003204.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.