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dc.contributor.authorGerig, S-Ben_US
dc.contributor.authorPinzon-Rodriguez, O.en_US
dc.contributor.authorMarschall, R.en_US
dc.contributor.authorWu, J-Sen_US
dc.contributor.authorThomas, N.en_US
dc.date.accessioned2020-10-05T02:02:00Z-
dc.date.available2020-10-05T02:02:00Z-
dc.date.issued2020-11-15en_US
dc.identifier.issn0019-1035en_US
dc.identifier.urihttp://dx.doi.org/10.1016/j.icarus.2020.113968en_US
dc.identifier.urihttp://hdl.handle.net/11536/155416-
dc.description.abstractWe have determined the dust coma brightness ratio between the dayside and the nightside (DS:NS) in OSIRIS images of comet 67P/Churyumov-Gerasimenko and compared them to results from numerical dust coma simulations to learn more about the dynamic processes that are involved in coma formation. The primary focus of this paper lies in the analysis of a subset of OSIRIS images acquired during one comet rotation on 11. April 2015 when the spacecraft was at a phase angle of 90 degrees and therefore directly above the terminator. The DS:NS ratio was found to be 2.49 +/- 0.18 on average - a very low value if insolation-driven sublimation of water dominates dust emission. We investigated two possible hypotheses: First, the influence of direct activity from non-illuminated (nightside) areas of the comet and second, the brightness contribution of large gravity-dominated particles in the innermost coma. For our numerical simulations, we used a combination of DSMC gas dynamics simulation and particle propagation by an equation of motion to simulate the dust coma. Our simulations show that direct activity from the nightside is preferred, contributing approximate to 10% of the total emission. We show that intensity profiles, used to quantify dust outflow behaviour, fit the observations better when nightside activity is present and we suggest that nightside gas emission by CO2 or CO is responsible for the observed dust flux. With the help of a simplified Keplerian modelling approach we exclude large particles on gravitationally bound or ballistic orbits from being the major contributor to the observed dust coma brightness. Additionally, we show the DS:NS ratio as a function of days to perihelion and observe that it is on a similar level as in the April OSIRIS time series from February to mid-June 2015, but increases towards a maximum of >= 4.07 +/- 0.49 shortly after perihelion passage. We suggest that this is correlated to the increasing importance of H2O production when approaching perihelion.en_US
dc.language.isoen_USen_US
dc.subjectRosettaen_US
dc.subjectSimulationen_US
dc.subjectDust comaen_US
dc.subjectNightside activityen_US
dc.titleDayside-to-nightside dust coma brightness asymmetry and its implications for nightside activity at Comet 67P/Churyumov-Gerasimenkoen_US
dc.typeArticleen_US
dc.identifier.doi10.1016/j.icarus.2020.113968en_US
dc.identifier.journalICARUSen_US
dc.citation.volume351en_US
dc.citation.spage0en_US
dc.citation.epage0en_US
dc.contributor.department機械工程學系zh_TW
dc.contributor.departmentDepartment of Mechanical Engineeringen_US
dc.identifier.wosnumberWOS:000561215600025en_US
dc.citation.woscount0en_US
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