CAOSP abstracts, Volume: 30, No.: 1, year: 2000
- Author(s): VANYSEK, V.; TICHY, M.; TICHA, J.; MORAVEC, Z.
- Journal: Contributions of the Astronomical Observatory Skalnate Pleso,
vol. 30, no. 1, p. 5-11.
- Date: 04/2000
- Title: Photometric studies of comets at the Klet Observatory
- Keyword(s): COMETS, 19P/BORRELLY, 122P/DE VICO, COMETARY DUST
- Pages: 5 -- 11
The preliminary results of the comet surface photometry performed in the
framework of the small bodies programme of the Klet Observatory are discussed.
The integrated brightness of the tail of comet 122P/de Vico has been used for
the determination of the dust flow characteristics in the tail. It is shown,
that in the dusty tail near coma, where the contribution of small ``fluffy''
and unstable dust particles to the surface brightness of the tail is
substantial, the decrease of integrated brightness with distance indicates
effects of some kind of disintegration mechanism. The apparent lifetime of
grains inferred from the tail photometry is less than one day at the
heliocentric distance 1 AU. This effect might be caused either by sublimation
or by electrostatic charge disruption of grains, and even the albedo change
should be considered. Since the narrow streams are presented on the tail images
of 122P/de Vico obtained with a R filter, a substantial contribution of the
ionized molecular species must be considered as another alternative. Among the
most abundant ions of the plasma tail are CO+ and H2O+. The contribution of
each of these species to the ion tail brightness in the red region must be
considered. Nevertheless, the discussed method for the determination of the
dissipation coefficient may also be applied here for the ion tail. In such a
case the effective lifetime of these species at heliocentric distance 1 AU, is
significantly shorter that 10 exp(5) s. Preliminary analysis of the brightness
distribution in the coma of 19P/Borrelly indicates that a population of larger
dust grains for which "mi" lower or equal than 1 dominates there.
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