Thermal model of water and CO activity of Comet C/1995 O1 (Hale-Bopp)

Gortsas, Nikolaos; Kührt, Ekkehard; Motschmann, U.; Keller, H. U.

doi:10.1016/j.icarus.2011.01.017

Cited by 29 publications

(31 citation statements)

References 44 publications

(73 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the fixed orbital parameters this depth is mainly determined by the thermal inertia of the nucleus material, and for the inertia values obtained from the MIRO measurements the heated depth does not exceed 30−40 m. However, there is another process that needs to be taken into account since it may modify the heat penetration depth into the deep interior, i.e., sublimation erosion (removal of ice and dust from the surface). Erosion leads to a moving boundary and, as a result, to a shrinking of the heated region (Gortas et al 2011). This problem is commonly referred to as a Stefan problem.…”

Section: Depth Of Super-volatiles: Model Resultsmentioning

confidence: 99%

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

Skorov

Rezac

Hartogh

et al. 2016

A&A

View full text Add to dashboard Cite

Aims. We develop a physical model to explain the potent outbursts that occurred in the fractured terrain of comet 67P near perihelion, and predict its temporal characteristics. Methods. The feasibility of the proposed mechanism is studied using a numerical model accounting for the relevant microscopic/macroscopic processes. We rely on the thermophysical, compositional, and geo-morphological data from the published measurements of respective instruments on board Rosetta. Results. The key idea of this novel mechanism is built around observations of fractures/cracks in the region of interest. It is argued that as the stresses on the nucleus increased during the perihelion approach, a crack deepening event occurred reaching the deeper material containing super-volatile ices in equilibrium with the surrounding. This sudden opening lead to a violent sublimation of the super-volatile ices. The time scales and mass release of this process are modeled and reported. In our modeling we pay attention to the question of the existence of super-volatile ices in the deeper interior for a long time, and the thermal equilibrium in the interior. Conclusions. The deepening of pre-existing cracks (fracture) into the material containing highly volatile ices can explain the observed outburst features. The sudden disequilibration of the steady-state reservoir of highly volatile ices results in a violent release of gas and dust. The proposed mechanism also explains the rapid shut down of this activity in accordance with the observations. The proposed mechanism is independent of solar illumination history of a given region, or the pre-existance of large sealed nucleus cavities.

show abstract

Section: Depth Of Super-volatiles: Model Resultsmentioning

confidence: 99%

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

Skorov

Rezac

Hartogh

et al. 2016

A&A

View full text Add to dashboard Cite

show abstract

“…Intuitively, given the temperatures derived in this work, the sublimation of CO and CO 2 within a few diurnal skin depths would sustain strong, continuous outgassing and dust emission after sunset. However, the sublimation of CO or CO 2 in the subsurface depends not only on insolation but also strongly on heat transport in the interior of the nucleus, and will significantly lower the surface and subsurface temperatures (Gortsas et al 2011). Our future work will entail the application of a more comprehensive and consistent thermo-physical model to investigate the plausibility of the diurnal pattern of sublimation of super-volatiles, such as CO and CO 2 (Hässig et al 2015), and its relevance to the observed dust activities after sunset.…”

Section: Discussionmentioning

confidence: 99%

“…Jets may also be caused by the sublimation of super-volatiles, such as CO or CO 2 , more likely governed by the interior condition (Prialnik & Bar-Nun 1990;Enzian 1999;Belton et al 2007;Belton 2010). The plausibility of the two scenarios can be tested via a modeling approach (Prialnik et al 2004;Gortsas et al 2011). The first scenario will be specifically investigated below, given that the sunset jets in our study are consistently observed near the illuminated area and rarely far into the night side and, hence, suggest a possible diurnal pattern of activity.…”

Section: A Model For Thermal Lag and Dust Activitymentioning

confidence: 99%

Sunset jets observed on comet 67P/Churyumov-Gerasimenko sustained by subsurface thermal lag

Shi

Sierks

et al. 2016

A&A

Self Cite

View full text Add to dashboard Cite

We present observations of sunset jets on comet 67P/Churyumov-Gerasimenko by Rosetta/OSIRIS camera. In late April 2015, when the comet was at a heliocentric distance of ∼1.8 AU, clusters of dust jets that originated in the Ma'at region on the comet's small lobe were identified from multiple images and were apparently sustained for about an hour beyond local sunset. Emanating from the shadowed nucleus, these jets became visible by solar illumination at their apparent sources up to only a few tens of meters above the nucleus surface. We investigate the plausibility of these jets as having been triggered by water ice sublimation and sustained by thermal lag in the subsurface beyond sunset. A general thermo-physical model was parameterized such that the thermal lag in the subsurface is consistent with the elapsed time of observation after sunset. It is found that the sublimation of water ice from a depth of 6 mm and with a low thermal inertia of 50 W m −2 K −1 s 1/2 could explain the spatial pattern and evolution of the apparent sources, particularly their disappearance due to the eventual cooling of the subsurface. Our analysis suggests that these sunset jets were essentially day-side dust activities that continued after sunset. Specific observational conditions for the sunset jets constrain their possible sources to mostly within the less abrupt, dusty terrains. The uneven distribution of these jets is possibly related to subsurface inhomogeneities in the dusty area.

show abstract

“…where C s is the solar constant (W m −2 ), A b the bolometric Bond albedo, R h the heliocentric distance (UA), and ξ the solar zenith distance calculated as (see Sekanina 1979;Fanale & Salvail 1984;Prialnik 2004;Gortsas et al 2011):…”

Section: Equations Of Conservation Of Energymentioning

confidence: 99%

A cometary nucleus model taking into account all phase changes of water ice: amorphous, crystalline, and clathrate

Marboeuf

Schmitt

Petit

et al. 2012

A&A

View full text Add to dashboard Cite

Context. Current theories, models of cometary nuclei and of ice formation in the protoplanetary disk, and laboratory studies suggest that cometary materials could be formed of pure crystalline water ice, amorphous water ice, clathrate hydrate, or a mixture of these structures of water ice. However, current models of cometary nuclei consider only two forms of ice during the thermodynamic evolution of comets: amorphous and crystalline water ices. Aims. In this work, we have developed a model of cometary nucleus that takes into account all water ice structures and phase changes in order to predict the outgassing profile of volatile molecules that could be measured by the Rosetta mission and can be used to constrain the structural type of ice existing in the interior of the Comet 67P/Churyumov-Gerasimenko, the target comet of the Rosetta mission, and, hopefully, its initial composition. Methods. We added the physic of formation/dissociation of clathrate hydrates in addition to others physical processes that are taken into account in models without clathrate hydrates. All thermal changes, as well as the release and trapping of gas with water phase changes are taken into account. Results. This model describes heat transmission, latent heat exchanges, all water ices structures and transitions (amorphous-to-pure crystalline, amorphous-to-clathrate hydrates and pure crystalline-to-clathrate hydrates and vise versa), sublimation/recondensation of volatile molecules in the nucleus, gas diffusion, gas released and trapped by crystallization and clathrate formation/dissociation processes, as well as gas and dust release and mantle formation at the surface. Applying this model to the comet 67P/ChuryumovGerasimenko, results show different outgassing profiles of volatiles molecules from the nucleus depending on the water ice structure, the distribution of volatile molecules between the "trapped" and "condensed" states in the nucleus and the thermal inertia of its porous matrix. Conclusions. Given these results, we pretend that this model is able to constrain the water ice structure and chemical composition in comets from outgassing profiles of volatile molecules, and especially those of the target comet of the Rosetta mission.

show abstract

Thermal model of water and CO activity of Comet C/1995 O1 (Hale-Bopp)

Cited by 29 publications

References 44 publications

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

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

Sunset jets observed on comet 67P/Churyumov-Gerasimenko sustained by subsurface thermal lag

A cometary nucleus model taking into account all phase changes of water ice: amorphous, crystalline, and clathrate

Contact Info

Product

Resources

About