The nature of two anomalous structures observed in the dust tail of Comet Bennett 1970. II - A possible Neck-Line Structure
Abstract
Three red-light photographs of Comet Bennett 1970II, taken at the Karl Schwarzschild Observatory, Tautenburg close to the date of the Earth passage through the comet nodal line, are presented. All the plates show an anomalous ray-shaped structure (RSS) stretching from the nucleus across a regular, edgewise-seen dust tail, and a short sunward spike (SWS), strongly recalling that of Comet Tago-Sato-Kosaka 1969 IX. The shape and the behaviour of the RSS during the relevant time strongly recall the sunward spike of Comet Arend-Roland 1957III observed under similar geometrical circumstances (although here the RSS is oriented in the direction opposite to the Sun, as the main tail). The spectral range of the observations, and other circumstantial proofs allow to consider such features as dusty structures. Image processing is developed in order to enhance the low visibility of the SWS, partly embedded in the coma. The classical explanation, based on the meteoric swarm, could explain, as in the case of Comet Arend-Roland, the RSS, but the ouly realistic model which can explain both the structures is the NLS model developed by Kimura and Liu (1977) using the rigorous treatment of the motion of the comet tail dust grains. A new complete model of these twodimensional structures is developed, whose results are able to explain the observations. In order to account for the shape and extension of the SWS, a dust ejection velocity from the inner coma >0.03 km s-1is required, in disagreement with the hypothesis of zero velocity release assumed in the meteoric swarm model.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 1987
- Bibcode:
- 1987A&A...176..358P
- Keywords:
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- Celestial Mechanics;
- Comet Tails;
- Cosmic Dust;
- Data Reduction;
- Image Processing;
- Photographic Plates;
- COMETS;
- STRUCTURE;
- ANOMALIES;
- COMET TAILS;
- BENNETT;
- COMPARISONS;
- DUST;
- EARTH-BASED OBSERVATIONS;
- FEATURES;
- CELESTIAL MECHANICS;
- IMAGE PROCESSING;
- PROCEDURE;
- ASTRONOMY;
- MODELS;
- MOTION;
- PHOTOGRAPHS;
- PARAMETERS;
- DENSITY;
- GEOMETRY;
- CALCULATIONS;
- THEORETICAL STUDIES;
- GRAINS;
- Astrophysics; Comets