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arXiv · 2111.15644

Ultraviolet Observations of Comet 96/P Machholz at Perihelion

J. C. Raymond·S. Giordano·S. Mancuso·M. S. Povich·A. Bemporad
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Abstract

Ultraviolet spectra of Comet 96/P Machholz were obtained during its 2002 perihelion with the UVCS instrument aboard 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 in H I Ly$α$ emission and an ion tail seen in C III. Radiation pressure on the hydrogen atoms produces a modest distortion of the shape of the Ly$α$ cloud as seen from SOHO, and it produces Doppler shifts up to 30 km s$^{-1}$ in the outer parts of the cloud. We estimate a ratio of C to H$_2$O similar to what is observed in other comets, so low carbon abundance does not account for the anomalously low C$_2$ and C$_3$ ratios to NH$_2$ observed at optical wavelengths.

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J. C. Raymond, S. Giordano, S. Mancuso, M. S. Povich, A. Bemporad. 2021-11-30. Ultraviolet Observations of Comet 96/P Machholz at Perihelion. https://doi.org/10.3847/1538-4357%2Fac3cbd

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