Other
Scientific paper
Dec 1996
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996jkass..29...65l&link_type=abstract
Journal of the Korean Astronomical Society, v. 29 Supplement, p.S65
Other
Scientific paper
Isotropic and axi-symmetric models of a cometary atmosphere, made up of H_2O and its daughter radicals (H, OH, O and H_2), have been computed using the Monte Carlo particle transport method. The approach on which the Monte Carlo models is based was checked against the cases of purely adiabatic expansion and of a vectorial model for OH, and was shown to be consistent with the results from other numerical techniques. The simulated velocity profile of water molecules in the optically thick coma (up to r = 10,000 km) is in good agreement with Giotto NMS (Neutral Mass Spectrometer) measurements of comet Halley in March, 1986. The detailed fit to the measured velocity profile in the outer coma requires the inclusion of rotational cooling of water molecules in this transition region from the optically thick to optically thin regime. The axi-symmetric model shows that the outward expansion of water molecules is mainly radial with negligible mean lateral velocity from the intermediate coma to the outer coma. The outflow velocity of water molecules increases with increasing local gas production rates, and the outflow velocity of H decreases with increasing local production rates. The isotropic model was also applied to comet Levy and it is shown that the simulated results can fit the 18-cm line profile by assuming an anisotropic distribution in the coma. The OH 1667 MHz transition is saturated (optically thick) from the inner coma to the intermediate coma and this results in a total reduction of about 25% in the retrieved gas production rate for comet Levy. The dynamic model of OH with collisions included is needed to give a better fit than the collisionless vectorial model.
Lee Myung Gyoon
Lyo A.-Ran
No associations
LandOfFree
The Brightest Stars in Galaxies as Distance Indicators does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Brightest Stars in Galaxies as Distance Indicators, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Brightest Stars in Galaxies as Distance Indicators will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1503610