PECULIAR PAIR OF DISTANT PERIODIC COMETS C/2002 A1 AND C/2002 A2 (LINEAR)

摘要

Distant comets C/2002 A1 and C/2002 A2 make up a peculiar pair that moves about the Sun in virtually identical, somewhat unstable orbits, extending currently between about 4.7 and 29 AU from the Sun. The two objects, observed since late 2001, are unquestionably of common origin. Analysis of their relative motion indicates that their parent body split nontidally most probably between mid-1977 and early 1979 at a heliocentric distance of 22.5 +- 0.1 AU and about 2.5 AU below the ecliptic, with a separation velocity of 2.7 +- 0.2 m s~(-1). The motion of C/2002 A2, the secondary component that trails behind the primary, is found to be affected by a nongravitational deceleration of (13.4 +- 1.5) x 10~(-5) units of solar gravitational acceleration relative to C/2002 A1, which is in a range of decelerations that companions of split comets are usually subjected to. C/2002 A2 was somewhat less condensed and, interestingly, brighter than C/2002 A1.