A model of short-lived outbursts on the 67P from fractured terrains

Skorov, Yu. V.; Rezac, Ladislav; Hartogh, P.; Bazilevsky, A. T.; Keller, H. U.

doi:10.1051/0004-6361/201628365

Cited by 32 publications

(21 citation statements)

References 65 publications

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“…For any bona fide parameter set the layer above the CO2 sublimation front amounts to several decimetres. The depth of CO is considerably larger because of its very low sublimation temperature and should be at least several meters (Skorov et al 2016). Even centimetre sized aggregates may still contain water ice if the effective pore size is in the 100 µm or smaller range.…”

Section: The Dichotomy Of the Gas Coma Com-positionmentioning

confidence: 99%

Seasonal mass transfer on the nucleus of comet 67P/Chuyumov–Gerasimenko

Keller

Mottola

Hviid

et al. 2017

Monthly Notices of the Royal Astronomical Society

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119

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We collect observational evidence that supports the scheme of mass transfer on the nucleus of comet 67P/Churyumov-Gerasimenko. The obliquity of the rotation axis of 67P causes strong seasonal variations. During perihelion the southern hemisphere is four times more active than the north. Northern territories are widely covered by granular material that indicates back fall originating from the active south. Decimetre sized chunks contain water ice and their trajectories are influenced by an anti-solar force instigated by sublimation. OSI-RIS observations suggest that up to 20 % of the particles directly return to the nucleus surface taking several hours of travel time. The back fall covered northern areas are active if illuminated but produce mainly water vapour. The decimetre chunks from the nucleus surface are too small to contain more volatile compounds such as CO2 or CO. This causes a north-south dichotomy of the composition measurements in the coma. Active particles are trapped in the gravitational minimum of Hapi during northern winter. They are "shock frozen" and only reactivated when the comet approaches the sun after its aphelion passage. The insolation of the big cavity is enhanced by self-heating, i. e. reflection and IR radiation from the walls. This, together with the pristinity of the active back fall, explains the early observed activity of the Hapi region. Sobek may be a role model for the consolidated bottom of Hapi. Mass transfer in the case of 67P strongly influences the evolution of the nucleus and the interpretation of coma measurements.

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Section: The Dichotomy Of the Gas Coma Com-positionmentioning

confidence: 99%

Seasonal mass transfer on the nucleus of comet 67P/Chuyumov–Gerasimenko

Keller

Mottola

Hviid

et al. 2017

Monthly Notices of the Royal Astronomical Society

Self Cite

119

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“…That the outbursts occurred most often at either early morning or afternoon indicates that they could have been triggered by thermal stress. Alternatively, the sudden opening of a fracture or crack, also because of thermal stress, could also lead to a violent sublimation of the super-volatile ices buried in the deep interior according to Skorov et al (2016).…”

Section: Introductionmentioning

confidence: 99%

Seasonal variations in source regions of the dust jets on comet 67P/Churyumov-Gerasimenko

Lai

Lee

et al. 2019

A&A

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Aims. We investigate the surface distribution of the source regions of dust jets on comet 67P/Churyumov-Gerasimenko as a function of time. Methods. The dust jet source regions were traced by the comprehensive imaging data set provided by the OSIRIS scientific camera. Results. We show in detail how the projected footpoints of the dust jets and hence the outgassing zone would move in consonance with the sunlit belt. Furthermore, a number of source regions characterized by repeated jet activity might be the result of local topographical variations or compositional heterogeneities. Conclusions. The spatial and temporal variations in source regions of the dust jets are influenced significantly by the seasonal effect. The strong dependence on the solar zenith angle and local time could be related to the gas sublimation process driven by solar insolation on a surface layer of low thermal inertia.

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“…3The most important cause of a potential temperature increase above 30 K therefore is surface heating by insolation and subsequent conductive heat transfer from the surface to the interior. However, Skorov et al (2016) showed that ice sublimation in near-surface regions does not only cause substantial surface ablation, but also prevents an appreciable temperature increase below a depth of about 10 m. Thus, the active comet does not come to a thermal equilibrium and the center temperature stays close to the formation value. The exact knowledge of T i is not a precondition for our analysis in any case, as expounded in Appendix B.…”

Section: Initial Conditionsmentioning

confidence: 99%

3D thermal modeling of two selected regions on comet 67P and comparison with Rosetta/MIRO measurements

Macher

Kömle

Skorov

et al. 2019

A&A

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Context. The Microwave Instrument for the Rosetta Orbiter (MIRO) was one of the key instruments of the Rosetta mission, which acquired a wealth of data, in particular as the orbiter moved in the close environment of comet 67P/Churyumov-Gerasimenko (August 2014–September 2016). It was the only instrument of the Rosetta payload that was able to measure temperatures in the near-subsurface layers of the cometary nucleus down to a depth of some centimeters. This range is most relevant for understanding the mechanisms of cometary activity. Aims. We simulate the 3D temperature distribution for two selected regions that were observed by MIRO in March 2015 when the comet was at a distance of about 2 au from the Sun. The importance of a full 3D treatment for a realistic subsurface temperature distribution and the thermal heat balance in the uppermost subsurface is investigated in comparison with analogous 1D simulations. Methods. For this purpose, we developed a numerical heat transfer model of the surface as well as the near-subsurface regions. It enabled us to solve the heat transfer equation in the subsurface volume with appropriate radiation boundary conditions taken into account. The comparison with 1D simulations was made on the basis of the same solar irradiation history. Results. Although the temperature gradient is predominantly normal to the comet surface, we still find that tangential flows may be responsible for local temperature differences of up to 30 K (a few Kelvin on the average) in the uppermost subsurface layers. From the results of the 3D simulations, we calculated the MIRO antenna temperature. A comparison with the actual measurements shows good agreement for the MIRO submillimeter channel, but there is a notable discrepancy for the millimeter channel. This last assessment is not related to the use of the 3D model; potential causes are discussed in some detail with a view to future studies.

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A model of short-lived outbursts on the 67P from fractured terrains

Cited by 32 publications

References 65 publications

Seasonal mass transfer on the nucleus of comet 67P/Chuyumov–Gerasimenko

Seasonal mass transfer on the nucleus of comet 67P/Chuyumov–Gerasimenko

Seasonal variations in source regions of the dust jets on comet 67P/Churyumov-Gerasimenko

3D thermal modeling of two selected regions on comet 67P and comparison with Rosetta/MIRO measurements

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