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An estimate the rotation period of cometary nuclei is important for
understanding and describing the physical processes of the cometary activity.
Unfortunately, the measurements of the rotation periods of the comet
nucleus depend on the model assumptions and it is one of the main reasons
for the scatter of the estimates given in various articles for a given comet.
We used the cross-correlation method, which is practically independent
from model parameters, in order to estimate the rotation period of the
nucleus of comet 29P/Schwasmann-Wachmann 1. Using this method we were
able to obtain the value of the angular shift of isolated low-contrast
structures. Comet 29P/Schwasmann-Wachmann 1 belongs to a class of Centaurus,
the members of which are considered to be the "fugitives" from the Kuiper
belt. Over many years of observations, the comet episodically demonstrated
outburst activity. The dust coma had never completely disappeared in
spite of different degrees of comet activity during the whole
period of observations. Although the comet has a perihelion distance
greater than 5 AU, it shows a significant activity beyond the sublimation
of water ice and has a rich emission spectrum. We have detected new
N2+ emission bands besides the known molecular
emission CN, CO+ in the spectra of the comet obtained at
the 6-m telescope (SAO RAS) using the focal reducer
SCORPIO.
Using the R-band photometric observation of the comet with
the SCORPIO
on December 2008, the estimates of the rotation period of the cometary
nucleus were obtained. We have found the jets against the bright dust
coma using the digital filters. The rotation period of the cometary
nucleus was obtained when the comet showed the low activity and the value
equal to 12.1±1.2 for the observations on December 2008.
The observations obtained at the
2-m telescope
(Terskol, Russia) during a new outburst of the comet, using similar
techniques showed that the period is unchanged, 11.7± 1.5 days.
The authors assume that this method of the estimation of the rotation
period comets, which have long-lived active structures in a coma, is
an optimal and independent from model parameters.
Published:
V.Ivanova, V.L.Afanasiev, P.P.Korsun, A.R.Baranskii, M.V.Andreev and
V.A.Ponomarenko
2012, Solar System Research, Vol.46, pp.313-319
Contact - Aleksandra Ivanova
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