Model for Cameron band emission in comets: A case for EPOXI mission target comet 103P/Hartley 2

Abstract

The CO2 production rate has been derived in comets using the Cameron band (a3Pi - X1Sigma) emission of CO molecule assuming that photodissociative excitation of CO2 is the main production mechanism of CO in a3Pi metastable state. We have devoloped a model for the production and loss of CO(a3Pi) which has been applied to comet 103P/Hartley 2: the target of EPOXI mission. Our model calculations show that photoelectron impact excitation of CO and dissociative excitation of CO2 can together contribute about 60-90% to the Cameron band emission. The modeled brightness of (0-0) Cameron band emission on comet Hartley 2 is consistent with Hubble Space Telescope observations for 3-5% CO2 (depending on model input solar flux) and 0.5% CO relative to water, where photoelectron impact contribution is about 50-75%. We suggest that estimation of CO2 abundances on comets using Cameron band emission may be reconsidered. We predict the height integrated column brightness of Cameron band of ~1300 R during EPOXI mission encounter period.

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References in corpus (4)

• The radiative lifetime of metastable CO ($a^3\Pi ,v=0$)
• Spitzer Space Telescope Observations of the Nucleus of Comet 103P/Hartley 2
• Optical observations of 23 distant Jupiter Family Comets, including 36P/Whipple at multiple phase angles
• The nucleus of 103P/Hartley 2, target of the EPOXI mission

Cited by in corpus (10)

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• The CO2 Abundance in Comets C/2012 K1 (PanSTARRS), C/2012 K5 (LINEAR), and 290P/Jager as Measured with Spitzer
• Model for Atomic Oxygen Visible Line Emissions in Comet C/1995 O1 Hale-Bopp
• Photochemistry of atomic oxygen green and red-doublet emissions in comets at larger heliocentric distances
• Model for the Production of CO Cameron band emission in Comet 1P/Halley
• Prediction of forbidden ultraviolet and visible emissions in comet 67P/Churyumov-Gerasimenko
• A photochemical model of ultraviolet atomic line emissions in the inner coma of comet 67P/Churyumov-Gerasimenko