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Astron. Astrophys. 348, 1020-1034 (1999)

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6. Summary

The continuum radiation of these comets can be described by the point source like emission of the nucleus and the extended halo emission, originating by the [FORMULA] density distribution being in thermal equilibrium with insolation. The center of the halo coincides with the nucleus. The inner part of the halo seems to be circularly symmetric. The steady "light" curve of the comets can be described by its geo- and heliocentric distances. The observed inner halo can be approximated by a Gaussian; the extended structure neglected in the Gaussian approximation contains 30 to 40 % of the flux density, depending on integration limits. The brightness temperature of the nucleus is probably close to equilibrium temperature and allows a determination of its size. The three most intensively observed "radio" comets seem to have a similar power law spectrum, indicating a similar particle spectrum. The apparent correlation of photometric diameter, halo size and mass, and dust production rate on the one hand and the nuclear mass on the other needs further proof. During the monitoring time none of these comets showed any significant internal variability or any transient outburst or IGH event.

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© European Southern Observatory (ESO) 1999

Online publication: August 13, 199