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Published June 7, 1993 | public
Journal Article Open

Observations of the plasma flow in comet P/Swift‐Tuttle


We present direct ground based observations of the plasma flow sunward and tailward of the nucleus of comet P/Swift‐Tuttle. The observations are long‐slit high resolution spectra of the H_2O^+ emission centered at 6199Å with a velocity resolution of about 7 km s^(−1) (FWHM) and a spatial resolution of about 10^4 km at the comet. Emission is visible from just inside the predicted position of the cometopause on the sunward side of the nucleus out to 5 × 10^5 km on the tailward side. The deceleration of the solar plasma on the sunward side is clearly observed as is the acceleration of cometary ions into the tail. These observations show the effectiveness of ground based methods for the systematic study of cometary plasmas and point to the need for a better theoretical understanding of their acceleration mechanisms.

Additional Information

© 1993 American Geophysical Union. Received: March 22, 1993; accepted 16 April 1993. We are indebted to Tony Misch at Lick Observatory for his continued assistance and to Don Yeomans for an updated ephemeris. MEB acknowledges the support of a NASA Graduate Fellowship, and HS is supported by NASA grant NAGW-2883.


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