Ultraviolet Observations of Comet 96/P Machholz at Perihelion

Journal
Date Issued
2022
Author(s)
Raymond, J. C.
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•
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Povich, Matthew S.
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DOI
Abstract
Ultraviolet spectra of Comet 96/P Machholz were obtained during its 2002 perihelion with the UltraViolet Coronagraph Spectrometer instrument on board the SOHO satellite. Emission from H i, C ii, C iii, and O i is detected near the nucleus. The outgassing rate is in line with the value extrapolated from rates at larger distances from the Sun, and abundances of C and O are estimated. Reconstructed images show a nearly spherical cloud of H i Lyα emission and an ion tail seen in C iii. Radiation pressure on the hydrogen atoms produces a modest distortion of the shape of the Lyα cloud as seen from SOHO and Doppler shifts up to 30 km s-1 in the outer parts of the cloud. We estimate a ratio of C to H2O similar to what is observed in other comets, so low carbon abundance does not account for the anomalously low C2 and C3 ratios to NH2 observed at optical wavelengths.
Volume
926
Issue
1
Start page
93
Uri
Url
Issn Identifier
0004-637X
Rights
open.access
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