Eileen Ryan (Magadalena Ridge Observatory, New Mexico Institute of Mining and Technology), William H. Ryan (Magadalena Ridge Observatory, New Mexico Institute of Mining and Technology)
Keywords: Multi-object systems
Abstract:
The lightcurves of objects in mutual orbits will display occultation and/or eclipse events, collectively referred to as mutual events, under favorable geometric circumstances. Given that the unresolved image of a multiple object system is simply the sum of the scattered light from each individual object, these mutual events will appear as attenuations in the total detected light when one object (resulting in an occultation) or its shadow (resulting in an eclipse) passes in front of the other. Under certain geometric circumstances, it is possible to have both types of events occurring simultaneously, resulting in an even deeper minimum of the observed lightcurve.
The identification of mutual event signatures in the lightcurves of asteroids has led to the detection of several asynchronous Near Earth Asteroid (Pravec et al. 2006) and Main Belt (Ryan et al. 2004, Warner et al. 2005, and Krugly et al. 2005) binary systems. Such asynchronous systems, where the rotation period of the primary object differs from the mutual orbital period of the system, usually display the most unambiguous signature of a binary system. Suspected binary systems where the primarys rotational and the mutual orbits period are synchronous have also been observed (Behrend et al. 2004). However, the binary nature of these systems is more difficult to confirm since the signatures of the mutual events appear simply as more extended depressions in the minima already resulting from the asteroids rotation.
Recently, there has been interest in identifying potentially hostile companions to artificial satellites. The detection of mutual events as described above is one possible method to accomplish this for non-resolved systems. However, these companions will typically be much smaller relative to the parent body than previously observed asteroid binary systems, and hence, the expected attenuations due to the mutual events will be rather modest. Therefore, we will explore the parameter space of relative sizes, orbital dimensions, and surface characteristics, and report on the practicality of applying this technique to the detection of maneuvering microsatellite companions to artificial resident space objects.
%Z Behrend et al., (854) Frostia, IAU Circular 8389, (1089) Tama, IAU Circular 8265, (1313) Berna, IAU Circular 8292, and (4492) Debussy, IAU Circular 835, 2004
Krugly et al., Binary main-belt asteroid 11264 Claudiomaccone, presented at Dynamics and Physics of Solar System Bodies, May 22-25, 2005, Kiev, Ukraine, 2005
Pravec et al., Photometric survey of near-Earth binary asteroids, Icarus 181, 63-93, 2006
Ryan,W.H., E. Ryan, and C. Martinez, 3782 Celle: Discovery of a Binary System within the Vesta Family of Asteroids. Planetary and Space Science, 52, 1093 -1101, 2004
Warner et al., (5905) Johnson, IAU Circular 8511 and (76818) 200 RG79, IAU Circular 8592, 2005
Date of Conference: September 10-14, 2006
Track: Poster