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The dust jets in the nucleus of comet 29P/Schwassmann-Wachmann 1

Russian version  

    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.
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
Fig.1. Right: the image of the comet 29P/Schwassmann-Wachmann 1 obtained at the 6-m telescope. Left: rotation of the jets in the dust coma of comet SW1 detected after the processing of the resulting images of the comet