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Formation of jets in Comet 19P/Borrelly by subsurface geysers

January 1, 2004

Observations of the inner coma of Comet 19P/Borrelly with the camera on the Deep Space 1 spacecraft revealed several highly collimated dust jets emanating from the nucleus. The observed jets can be produced by acceleration of evolved gas from a subsurface cavity through a narrow orifice to the surface. As long as the cavity is larger than the orifice, the pressure in the cavity will be greater than the ambient pressure in the coma and the flow from the geyser will be supersonic. The gas flow becomes collimated as the sound speed is approached and dust entrainment in the gas flow creates the observed jets. Outside the cavity, the expanding gas loses its collimated character, but the density drops rapidly decoupling the dust and gas, allowing the dust to continue in a collimated beam. The hypothesis proposed here can explain the jets seen in the inner coma of Comet 1P/Halley as well, and may be a primary mechanism for cometary activity. ?? 2003 Published by Elsevier Inc.

Publication Year 2004
Title Formation of jets in Comet 19P/Borrelly by subsurface geysers
DOI 10.1016/j.icarus.2003.08.020
Authors R.V. Yelle, L. A. Soderblom, J.R. Jokipii
Publication Type Article
Publication Subtype Journal Article
Series Title Icarus
Index ID 70027691
Record Source USGS Publications Warehouse