The motion of dust and gas in the heads of comets with type II tails |
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| Authors: | Karl Wurm Augusto Mammano |
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| Institution: | (1) Asiago Observatory, Italy |
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| Abstract: | Photographs of Comet Bennett 1969i taken in the dust-scattered continuum reveal that the dust particles, leading to the formation of the type II tail, leave the vicinity of the nucleus only within a certain cone with the aperture in the direction to the Sun. Three parabolic envelopes embracing the nucleus are formed by the dust (vertex always about on the radius vector) reaching distances from the nucleus of 30 000, 60 000 and 100 000 km.There exists no relation between the production and motion of this dust and the production and motion of the neutral coma gases. The cone of expulsion of the dust is identical with the cone of expulsion for the ions leading to the formation of the type I tail. Dust- and ion envelopes have, however, different kinematical properties. The cone of expulsion is identical with Bessel's  Ausströmungskegel of visible matter observed by him in Comet Halley 1835.Comet Bennett is compared with Comet Halley 1910; they are related in many respects although Comet Halley had a lower dust production than the Comet Bennett.We ascribe to the dust particles of the tail II from the beginning of the expulsion an electrical charge. |
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