Abstract
We analyse the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) - the Double FocusingMass Spectrometer data between 2014 August and 2016 February to examine the effect of seasonal variations on the four major species within the coma of 67P/Churyumov- Gerasimenko (H2O, CO2, CO, and O2), resulting from the tilt in the orientation of the comet's spin axis. Using a numerical data inversion, we derive the non-uniform activity distribution at the surface of the nucleus for these species, suggesting that the activity distribution at the surface of the nucleus has not significantly been changed and that the differences observed in the coma are solely due to the variations in illumination conditions.Athree-dimensional Direct Simulation Monte Carlo model is applied where the boundary conditions are computed with a coupling of the surface activity distributions and the local illumination. The model is able to reproduce the evolution of the densities observed by ROSINAincluding the changes happening at equinox. While O2 stays correlated with H2O as it was before equinox, CO2 and CO, which had a poor correlation with respect to H2O pre-equinox, also became well correlated with H2O post-equinox. The integration of the densities from the model along the line of sight results in column densities directly comparable to the VIRTIS-H observations. Also, the evolution of the volatiles' production rates is derived from the coma model showing a steepening in the production rate curves after equinox. The model/data comparison suggests that the seasonal effects result in the Northern hemisphere of 67P's nucleus being more processed with a layered structure while the Southern hemisphere constantly exposes new material.
| Original language | English (US) |
|---|---|
| Pages (from-to) | S156-S169 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 462 |
| DOIs | |
| State | Published - 2016 |
Fingerprint
Keywords
- Comets: general
- Comets: individual: 67P/Churyumov-Gerasimenko
- Space vehicles
- Space vehicles: instruments
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
Cite this
Direct Simulation Monte Carlo modelling of the major species in the coma of comet 67P/Churyumov-Gerasimenko. / the VIRTIS and the ROSINA teams.
In: Monthly Notices of the Royal Astronomical Society, Vol. 462, 2016, p. S156-S169.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Direct Simulation Monte Carlo modelling of the major species in the coma of comet 67P/Churyumov-Gerasimenko
AU - the VIRTIS and the ROSINA teams
AU - Fougere, Nicolas
AU - Altwegg, K.
AU - Berthelier, J. J.
AU - Bieler, A.
AU - Bockelée-Morvan, D.
AU - Calmonte, U.
AU - Capaccioni, F.
AU - R. Combi, M.
AU - De Keyser, J.
AU - Debout, V.
AU - Erard, S.
AU - Fiethe, B.
AU - Filacchione, G.
AU - Fink, Uwe -
AU - Fuselier, S. A.
AU - Gombosi, T. I.
AU - Hansen, K. C.
AU - Hässig, M.
AU - Huang, Z.
AU - Le Roy, L.
AU - Leyrat, C.
AU - Migliorini, A.
AU - Piccioni, G.
AU - Rinaldi, G.
AU - Rubin, M.
AU - Shou, Y.
AU - Tenishev, V.
AU - Toth, G.
AU - Tzou, C. Y.
PY - 2016
Y1 - 2016
N2 - We analyse the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) - the Double FocusingMass Spectrometer data between 2014 August and 2016 February to examine the effect of seasonal variations on the four major species within the coma of 67P/Churyumov- Gerasimenko (H2O, CO2, CO, and O2), resulting from the tilt in the orientation of the comet's spin axis. Using a numerical data inversion, we derive the non-uniform activity distribution at the surface of the nucleus for these species, suggesting that the activity distribution at the surface of the nucleus has not significantly been changed and that the differences observed in the coma are solely due to the variations in illumination conditions.Athree-dimensional Direct Simulation Monte Carlo model is applied where the boundary conditions are computed with a coupling of the surface activity distributions and the local illumination. The model is able to reproduce the evolution of the densities observed by ROSINAincluding the changes happening at equinox. While O2 stays correlated with H2O as it was before equinox, CO2 and CO, which had a poor correlation with respect to H2O pre-equinox, also became well correlated with H2O post-equinox. The integration of the densities from the model along the line of sight results in column densities directly comparable to the VIRTIS-H observations. Also, the evolution of the volatiles' production rates is derived from the coma model showing a steepening in the production rate curves after equinox. The model/data comparison suggests that the seasonal effects result in the Northern hemisphere of 67P's nucleus being more processed with a layered structure while the Southern hemisphere constantly exposes new material.
AB - We analyse the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) - the Double FocusingMass Spectrometer data between 2014 August and 2016 February to examine the effect of seasonal variations on the four major species within the coma of 67P/Churyumov- Gerasimenko (H2O, CO2, CO, and O2), resulting from the tilt in the orientation of the comet's spin axis. Using a numerical data inversion, we derive the non-uniform activity distribution at the surface of the nucleus for these species, suggesting that the activity distribution at the surface of the nucleus has not significantly been changed and that the differences observed in the coma are solely due to the variations in illumination conditions.Athree-dimensional Direct Simulation Monte Carlo model is applied where the boundary conditions are computed with a coupling of the surface activity distributions and the local illumination. The model is able to reproduce the evolution of the densities observed by ROSINAincluding the changes happening at equinox. While O2 stays correlated with H2O as it was before equinox, CO2 and CO, which had a poor correlation with respect to H2O pre-equinox, also became well correlated with H2O post-equinox. The integration of the densities from the model along the line of sight results in column densities directly comparable to the VIRTIS-H observations. Also, the evolution of the volatiles' production rates is derived from the coma model showing a steepening in the production rate curves after equinox. The model/data comparison suggests that the seasonal effects result in the Northern hemisphere of 67P's nucleus being more processed with a layered structure while the Southern hemisphere constantly exposes new material.
KW - Comets: general
KW - Comets: individual: 67P/Churyumov-Gerasimenko
KW - Space vehicles
KW - Space vehicles: instruments
UR - http://www.scopus.com/inward/record.url?scp=85015813160&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85015813160&partnerID=8YFLogxK
U2 - 10.1093/mnras/stw2388
DO - 10.1093/mnras/stw2388
M3 - Article
AN - SCOPUS:85015813160
VL - 462
SP - S156-S169
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
ER -