Coma morphology of comet 67P controlled by insolation over irregular nucleus

Shi, Xian; Hu, Xuanyu; Mottola, S.; Sierks, H.; Keller, H. U.; Rose, Martin G.; Güttler, C.; Fulle, M.; Fornasier, S.; Agarwal, Jessica; Pajola, M.; Tubiana, C.; Bodewits, Dennis; Barbieri, C.; Lamy, Philippe; Rodrigo, R.; Koschny, D.; Barucci, M. A.; Bertaux, Jean-Loup; Bertini, Ivano; Boudreault, S.; Cremonese, G.; Deppo, V. Da; Davidsson, B.; Debei, S.; Cecco, M. De; Deller, Jakob; Groussin, O.; Gutiérrez, P. J.; Hviid, S. F.; Ip, W.-H.; Jordá, L.; Knollenberg, J.; Kovács, Gábor; Kramm, J. R.; Kührt, Ekkehard; Küppers, M.; Lara, L. M.; Lazzarin, M.; Moreno, J. J. Lopez; Marzari, F.; Naletto, G.; Oklay, N.; Tóth, I.; Vincent, J.-B.

doi:10.1038/s41550-018-0481-5

Cited by 23 publications

(22 citation statements)

References 38 publications

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“…We also observe a direct link between 67P's coma and the depressions (Shi et al, ). OSIRIS observations from the same period (March 14 and May 10) show a significant amount of dust coming from the location of the depressions (see SOM; Figure S4/S10).…”

Section: Observational Evidence Of Subsurface Water Ice and Mass Losssupporting

confidence: 75%

Migrating Scarps as a Significant Driver for Cometary Surface Evolution

Birch

Hayes

Umurhan

et al. 2019

Geophysical Research Letters

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Rosetta observations of 67P/Churyumov‐Gerasimenko (67P) reveal that most changes occur in the fallback‐generated smooth terrains, vast deposits of granular material blanketing the comet's northern hemisphere. These changes express themselves both morphologically and spectrally across the nucleus, yet we lack a model that describes their formation and evolution. Here we present a self‐consistent model that thoroughly explains the activity and mass loss from Hapi's smooth terrains. Our model predicts the removal of dust via reradiated solar insolation localized within depression scarps that are substantially more ice rich than previously expected. We couple our model with numerous Rosetta observations to thoroughly capture the seasonal erosion of Hapi's smooth terrains, where local scarp retreat gradually removes the uppermost dusty mantle. As sublimation‐regolith interactions occur on rocky planets, comets, icy moons, and Kuiper belt objects, our coupled model and observations provide a foundation for future understanding of the myriad of sublimation‐carved worlds.

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Section: Observational Evidence Of Subsurface Water Ice and Mass Losssupporting

confidence: 75%

Migrating Scarps as a Significant Driver for Cometary Surface Evolution

Birch

Hayes

Umurhan

et al. 2019

Geophysical Research Letters

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“…(b) the outburst of December 13, 2015, and its source in the southern outskirts of the Low bank, near the pancake feature. near sunset has also been observed in other sites (Shi et al 2016(Shi et al , 2018. It shows that subsurface heat diffusion and thermal-lagged water sublimation (Prialnik et al 2008) at 1.8 AU are enough to sustain activity for several hours after solar input has ceased.…”

Section: Low Bank: Patch 1 and Surroundingssupporting

confidence: 64%

“…Both C6 and F1 could have been depleted through a low steady dust production rate. The diurnal cycle alongside a low thermal inertia leads to a time-lagged thermal-wave penetration of a few millimeters and can sustain outgassing and dust removal through hours after sunset (Shi et al 2016(Shi et al , 2018. During the cooling down late at night, the uppermost layer is again drenched by ices that percolate and recondensate from ice-rich layers below.…”

Section: Activity Mechanismmentioning

confidence: 99%

Pronounced morphological changes in a southern active zone on comet 67P/Churyumov-Gerasimenko

Hasselmann

Barucci

Fornasier

et al. 2019

A&A

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A smooth deposit in the southern Khonsu region has been seen in ESA/Rosetta observations as active during the second half of 2015, when the southern summer coincided with the perihelion passage of 67P/Churyumov-Gerasimenko (67P). Image color sequences acquired by the OSIRIS instrument in the period of January 2015 to July 2016, pre-and post-perihelion, show the occurrence of several small transient events as well as three massive outbursts (∼10 to 1500 tons). High spatial resolution images taken one year and a half apart allowed us to track a variety of sources: the formation of cavities that are 1.3-14 m deep, ice-enriched patches, scarp retraction, and a second 50 m-wide boulder. We then estimated their masses and the dust mass of their corresponding plumes and outbursts. In particular, the deformation left by that boulder and its lack of talus may provide evidence for the lifting and subsequent falling back to the surface of large blocks. We calculate that a minimum vapor production rate of 1.4 × 10 24 m −2 s −1 is required to lift such an object. The comparison of the masses that are lost in the new cavities to the dust mass of outbursts gives indirect evidence of highly volatile ice pockets underneath. The spectrophotometric analysis and boulder counting also provides evidence for cavities that formed only 30 m apart with different spectral slopes, two long-standing ice patches, and local variations in the boulder-size frequency distribution. All this points to sub-surface ice pockets with different degrees of depth. Finally, the total mass of the morphological changes compared to most recent calculations of the total released mass by activity on 67P is estimated to be between 1.5 and 4.2%. This means that as many as about 25 similar active zones across the nucleus would be enough to sustain the entire cometary activity.

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“…Forward modeling of cometary activity, and link to topography, and particularly the interaction of dust and gas flows in "jets", have been published by many authors. Prominent results can be found for instance in Crifo et al (2005), Kramer and Noack (2016), Marschall et al (2017), Shi et al (2018). Such simulations provide a strong strong support for the topography driven model with a very repetitive coma structure with each nucleus rotation, with 90% correlation between simulation and measured intensity around the nucleus (Kramer and Noack, 2016).…”

Section: Active Sourcesmentioning

confidence: 62%

“…The collimation is mostly due to interactions of the flow with the topography, which explains why one is more likely to observe jets from cliff and pits rather than smooth, flat terrains. A more recent example including numerical simulations of this effect can be found in Shi et al (2018).…”

Section: Wake-upmentioning

confidence: 99%

Local Manifestations of Cometary Activity

et al. 2019

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Comets are made of volatile and refractory material and naturally experience various degrees of sublimation as they orbit around the Sun. This gas release, accompanied by dust, represents what is traditionally described as activity. Although the basic principles are well established, most details remain elusive, especially regarding the mechanisms by which dust is detached from the surface and subsequently accelerated by the gas flows surrounding the nucleus.During its 2 years rendez-vous with comet 67P/Churyumov-Gerasimenko, ESA's Rosetta has observed cometary activity with unprecedented details, in both the inbound and outbound legs of the comet's orbit. This trove of data provides a solid ground on which new models of activity can be built. In this chapter, we review how activity manifests at close distance from the surface, establish a nomenclature for the different types of observed features, discuss how activity is at the same time transforming and being shaped by the topography, and finally address several potential mechanisms.

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Coma morphology of comet 67P controlled by insolation over irregular nucleus

Cited by 23 publications

References 38 publications

Migrating Scarps as a Significant Driver for Cometary Surface Evolution

Migrating Scarps as a Significant Driver for Cometary Surface Evolution

Pronounced morphological changes in a southern active zone on comet 67P/Churyumov-Gerasimenko

Local Manifestations of Cometary Activity

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