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Imaging Borrelly |
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| Authors: | LA Soderblom DC Boice RH Brown RL Kirk RM Nelson BR Sandel N Thomas |
| Institution: | a United States Geological Survey, 2255 N Gemini Drive, Flagstaff, AZ 86001, USA b Southwest Research Institute, Space Sciences and Engineering Division, 6220 Culebra Road, PO Drawer 28510, San Antonio, TX 78228-0510, USA c Department of Physics, The University of Central Florida, PO Box 162385, Orlando, FL 32816-2385, USA d Departments of Planetary Sciences and Astronomy, University of Arizona, 1629 E. University Boulevard, Tucson, AZ 85721, USA e Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA f German Aerospace Center, Institute of Planetary Research, Rutherfordstrasse 2, D-12489 Berlin, Germany g Lunar and Planetary Laboratory, 1040 East Fourth Street, Room 901, University of Arizona, Tucson, AZ 85721, USA h Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 400, Boulder, CO 80302, USA i Space Research and Planetology Division, Physikalisches Institut, Sidlerstr. 5, CH-3012 Bern, Switzerland |
| Abstract: | The nucleus, coma, and dust jets of short-period Comet 19P/Borrelly were imaged from the Deep Space 1 spacecraft during its close flyby in September 2001. A prominent jet dominated the near-nucleus coma and emanated roughly normal to the long axis of nucleus from a broad central cavity. We show it to have remained fixed in position for more than 34 hr, much longer than the 26-hr rotation period. This confirms earlier suggestions that it is co-aligned with the rotation axis. From a combination of fitting the nucleus light curve from approach images and the nucleus' orientation from stereo images at encounter, we conclude that the sense of rotation is right-handed around the main jet vector. The inferred rotation pole is approximately perpendicular to the long axis of the nucleus, consistent with a simple rotational state. Lacking an existing IAU comet-specific convention but applying a convention provisionally adopted for asteroids, we label this the north pole. This places the sub-solar latitude at ∼60° N at the time of the perihelion with the north pole in constant sunlight and thus receiving maximum average insolation. |
| Keywords: | Comet Imaging Nucleus Topography Coma Dust jet Short-period comets 19P/Borrelly Borrelly Deep Space 1 Rotation axis Rotation pole |
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