Five new and three improved mutual orbits of transneptunian binaries
Abstract
We present three improved and five new mutual orbits of transneptunian binary systems (58534) LogosZoe, (66652) BorasisiPabu, (88611) TeharonhiawakoSawiskera, (123509) 2000 WK _{183}, (149780) Altjira, 2001 QY _{297}, 2003 QW _{111}, and 2003 QY _{90} based on Hubble Space Telescope and Keck II laser guide star adaptive optics observations. Combining the five new orbit solutions with 17 previously known orbits yields a sample of 22 mutual orbits for which the period P, semimajor axis a, and eccentricity e have been determined. These orbits have mutual periods ranging from 5 to over 800 days, semimajor axes ranging from 1600 to 37,000 km, eccentricities ranging from 0 to 0.8, and system masses ranging from 2 × 10 ^{17} to 2 × 10 ^{22} kg. Based on the relative brightnesses of primaries and secondaries, most of these systems consist of near equalsized pairs, although a few of the most massive systems are more lopsided. The observed distribution of orbital properties suggests that the most looselybound transneptunian binary systems are only found on dynamically cold heliocentric orbits. Of the 22 known binary mutual orbits, orientation ambiguities are now resolved for 9, of which 7 are prograde and 2 are retrograde, consistent with a random distribution of orbital orientations, but not with models predicting a strong preference for retrograde orbits. To the extent that other perturbations are not dominant, the binary systems undergo Kozai oscillations of their eccentricities and inclinations with periods of the order of tens of thousands to millions of years, some with strikingly high amplitudes.
 Publication:
 Icarus
 Pub Date:
 June 2011
 DOI:
 10.1016/j.icarus.2011.03.012
 arXiv:
 arXiv:1103.2751
 Bibcode:
 2011Icar..213..678G
 Keywords:

 Astrophysics  Earth and Planetary Astrophysics
 EPrint:
 In press in Icarus, 29 pages, 5 figures, 13 tables