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Irish Astr. J., 23(2), 151156, (1996) N. W. HARRIS & M. E. BAILEY THE COMETARY COMPONENT OF THE NEAREARTH OBJECT
 

Summary: Irish Astr. J., 23(2), 151­156, (1996) N. W. HARRIS & M. E. BAILEY
THE COMETARY COMPONENT OF THE NEAR­EARTH OBJECT
POPULATION
N. W. HARRIS & M. E. BAILEY
Armagh Observatory, College Hill, Armagh BT61 9DG
email: nwh@star.arm.ac.uk, meb@star.arm.ac.uk
ABSTRACT. The problem of the origin of Near­Earth Objects (NEOs), whether predominantly cometary or asteroidal, has
attracted much recent interest. In this work, we consider NEOs to have perihelion distances q ! 1:4 AU and separate them
according to their aphelion distances into two broad classes: Class 1 NEOs have aphelia Q ? 4:2 AU, allowing these objects
possibly to have close approaches to Jupiter; whereas Class 2 objects have Q ! 4:2 AU. The latter comprise the majority
(about 90%) of the known NEO population and are dynamically `decoupled' from close Jovian encounters. This paper presents
preliminary results from long­term numerical integrations of hypothetical Jupiter­family comets, which according to these
definitions would, if inactive, be considered as Class 1 `cometary' NEOs, or `cometary asteroids'. In particular, we evaluate
the transfer probabilities to Class 2 orbits, by both gravitational and non­gravitational mechanisms, and estimate the overall
cometary contribution to the number of objects in Class 1 and Class 2. Our results are compared with estimates of the rate of
injection of NEOs from the main asteroid belt.
1. NEAR­EARTH OBJECTS
Near­Earth Objects (NEOs) are small bodies of asteroidal ap­
pearance whose perihelia, q, lie in the region of the terrestrial
planets (q ! 1:4 AU), and whose aphelia, Q, typically lie within

  

Source: Armagh Observatory

 

Collections: Physics