The Split Nucleus of Comet Wilson (C/1986 P1 = 1987 VII)

摘要: Abstract We present CCD observations of Comet Wilson (C/1986 P1 = 1987 VII) from 26 nights during the time period 1986 October to 1991 February, which brackets perihelion, During observing run 1988 comet was observed have split into two fragments. Our broadband photometry, along with photometry International Cometary Quarterly , shows a steady decline in brightness post-perihelion, an outburst between heliocentric distances r 2.8 and 3.3 AU November. By ≈ 7 AU, fragment had faded respect parent no longer centrally condensed. A limit m R 25, when at 12.65 constrains primary nucleus maximum radius 5 km, assuming albedo 0.04. The accuracy direct orbital solutions for body determine splitting limited by presence significant nongravitational forces coverage. used relative position calculate consistent outburst. discuss possible causes splitting. coma surface-brightness profile fell off as p -1 (characteristic canonical steady-state under influence radiation pressure) all data exception taken November gradient -1.3 . This steeper slope probably caused injection new material October, there break may be interpreted distance grains are swept tail. profiles suggested grain velocities few x 10 2 sec 1 hundred micrometers. Finson-Probstein dust modeling showed that ejection began preperihelion gt; 6 peaking near perihelion very rapid thereafter, occurring roughly 170 days post-perihelion. found evidence existence discrete features coma. Both nuclei grew redder time, being than parent, picture smaller leaving field view aperture more quickly larger grains.