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

Anil Bhardwaj, Susarla Raghuram
2011 Monthly Notices of the Royal Astronomical Society: Letters  
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
more » ... te 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.
doi:10.1111/j.1745-3933.2010.00998.x fatcat:woeofvpewfed5hk2bqhxipm33a