Investigation into the disparate origin of CO2 and H2O outgassing for Comet 67/P

摘要: Abstract We present an investigation of the emission intensity CO 2 and H O their distribution in coma 67P/ Churyumov–Gerasimenko obtained by VIRTIS-M imaging spectrometer on Rosetta mission. analyze 4 data cubes from Feb. 28, 7 April 27, 2015. For both sets spacecraft was at a sufficiently large distance comet to allow images whole nucleus surrounding coma. find that unlike water which has reasonably predictable behavior correlates well with solar illumination, outgasses mostly local regions or spots. Furthermore for evolves almost exclusively southern hemisphere, region not received illumination since comet's last perihelion passage. Because have such disparate origins, deriving mixing ratios column density measurements cannot provide meaningful measurement /H ratio comet. obtain total production rates integrating band annulus pro-forma rate ∼5.0% ∼2.5% 28 respectively. highly variable nature evolution surface we do believe these numbers are diagnostic bulk composition. our provides explanation observed variations reported literature ratios. Our maps indicate that, besides difference vapor pressure two gases, this depends rotational orientation combined its complex geometric shape can result quite erosion different areas as northern hemisphere. 2.21AU Sun is 2.5 × 10 26 molecules/s while 27 1.76 AU it 4.65 × 10 . about 83% resides illuminated portion 17% night side. also make attempt fraction coming active neck versus rest pole-on view estimate 60% derives area. A rough evaporation yields 5 × 10 19 molecules/s/m Spatial radial profiles side comet, extending 1.78 6.47 km center, show follows model predictions well, gas accelerating expands into dayside profile allows us empirical determination expansion velocity water. On spatial 1/ ρ The exhibit any acceleration but closely matched profile.