A simple model for understanding the DIM dust measurement at comet 67P/Churyumov–Gerasimenko

Podolak, M.; Flandes, A.; Corte, Vincenzo Della; Krüger, Harald

doi:10.1016/j.pss.2016.04.006

Cited by 7 publications

(5 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The observational evidence thus far indicates higher abundance of CO 2 from the unilluminated southern heminucleus (Hässig et al 2015) and, in particular, its depletion in Ma'at, Ash, Seth(-Hapi), and (Aten-)Babi regions in the northern hemi-nucleus where surface changes were detected (Bockelée-Morvan et al 2015;Fink et al 2016;Migliorini et al 2016). Podolak et al (2016) suggested that the measured CO 2 production rate, a few percent of water production, is insufficient to account for the typical speed of dust grains at meters per second.…”

Section: Discussionmentioning

confidence: 97%

Seasonal erosion and restoration of the dust cover on comet 67P/Churyumov-Gerasimenko as observed by OSIRIS onboard Rosetta

Shi

Sierks

et al. 2017

A&A

View full text Add to dashboard Cite

Context. Dust deposits or dust cover are a prevalent morphology in the northern hemi-nucleus of comet 67P/Churyumov-Gerasimenko (67P). The evolution of the dust deposits was captured by the OSIRIS camera system onboard the Rosetta spacecraft having escorted the comet for over two years. The observations shed light on the fundamental role of cometary activity in shaping and transforming the surface morphology. Aims. We aim to present OSIRIS observations of surface changes over the dust deposits before and after perihelion. The distribution of changes and a timeline of their occurrence are provided. We perform a data analysis to quantify the surface changes and investigate their correlation to water activity from the dust deposits. We further discuss how the results of our investigation are related to other findings from the Rosetta mission. Methods. Surface changes were detected via systematic comparison of images, and quantified using shape-from-shading technique. Thermal models were applied to estimate the erosion of water ice in response to the increasing insolation over the areas where surface changes occurred. Modeling results were used for the interpretation of the observed surface changes. Results. Surface changes discussed here were concentrated at mid-latitudes, between about 20• N and 40• N, marking a global transition from the dust-covered to rugged terrains. The changes were distributed in open areas exposed to ample solar illumination and likely subject to enhanced surface erosion before perihelion. The occurrence of changes followed the southward migration of the sub-solar point across the latitudes of their distribution. The erosion at locations of most changes was at least about 0.5 m, but most likely did not exceed several meters. The erosive features before perihelion had given way to a fresh, smooth cover of dust deposits after perihelion, suggesting that the dust deposits had been globally restored by at least about 1 m with ejecta from the intensely illuminated southern hemi-nucleus around perihelion, when the north was inactive during polar night. Conclusions. The erosion and restoration of the northern dust deposits are morphological expressions of seasonality on 67P. Based on observations and thermal modeling results, it is inferred that the dust deposits contained a few percent of water ice in mass on average. Local inhomogeneity in water abundance at spatial scales below tens of meters is likely. We suspect that dust ejected from the deposits may not have escaped the comet in bulk. That is, at least half of the ejected mass was afloat in the inner-coma or/and redeposited over other areas of the nucleus.

show abstract

Section: Discussionmentioning

confidence: 97%

Seasonal erosion and restoration of the dust cover on comet 67P/Churyumov-Gerasimenko as observed by OSIRIS onboard Rosetta

Shi

Sierks

et al. 2017

A&A

View full text Add to dashboard Cite

show abstract

“…They are consistent with a particle radius of 0.9 mm, density of 250 kg m −3 , and porosity close to 90 %. Data and estimations also indicate that the particle likely moved at near 4 m s −1 with respect to the comet (Podolak et al 2016;Flandes et al 2018).…”

Section: Dimmentioning

confidence: 90%

Synthesis of the morphological description of cometary dust at comet 67P/Churyumov-Gerasimenko

Güttler

Mannel

Rotundi

et al. 2019

A&A

139

View full text Add to dashboard Cite

Before Rosetta, the space missions Giotto and Stardust shaped our view on cometary dust, supported by plentiful data from Earth based observations and interplanetary dust particles collected in the Earth's atmosphere. The Rosetta mission at comet 67P/Churyumov-Gerasimenko was equipped with a multitude of instruments designed to study cometary dust. While an abundant amount of data was presented in several individual papers, many focused on a dedicated measurement or topic. Different instruments, methods, and data sources provide different measurement parameters and potentially introduce different biases. This can be an advantage if the complementary aspect of such a complex data set can be exploited. However, it also poses a challenge in the comparison of results in the first place. The aim of this work therefore is to summarise dust results from Rosetta and before. We establish a simple classification as a common framework for inter-comparison. This classification is based on a dust particle's structure, porosity, and strength as well as its size. Depending on the instrumentation, these are not direct measurement parameters but we chose them as they were the most reliable to derive our model. The proposed classification already proved helpful in the Rosetta dust community and we propose to take it into consideration also beyond. In this manner we hope to better identify synergies between different instruments and methods in the future.

show abstract

“…if using C d ∼ 4/3 (Epstein 1924;Podolak et al 2016) for spherical dust particles. For present-day Phaethon, considering a maximum surface temperature of ∼800 K near perihelion, but a steady mean gas flux of J s <∼ 3 × 10 17 m −2 s −1 , the critical radius b max is only about 1.8 μm.…”

Section: Dust Accelerationmentioning

confidence: 99%

What mechanisms dominate the activity of Geminid Parent (3200) Phaethon?

Liangliang

Spohn

2018

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

A long-term sublimation model to explain how Phaethon could provide the Geminid stream is proposed. We find that it would take ∼6 Myr or more for Phaethon to lose all of its internal ice (if ever there was) in its present orbit. Thus, if the asteroid moved from the region of a 5:2 or 8:3 mean motion resonance with Jupiter to its present orbit less than 1 Myr ago, it may have retained much of its primordial ice. The dust mantle on the sublimating body should have a thickness of at least 15 m but the mantle could have been less than 1 m thick 1000 yr ago. We find that the total gas production rate could have been as large as 10 27 s −1 then, and the gas flow could have been capable of lifting dust particles of up to a few centimetres in size. Therefore, gas production during the past millennium could have been sufficient to blow away enough dust particles to explain the entire Geminid stream. For present-day Phaethon, the gas production is comparatively weak. But strong transient gas release with a rate of ∼4.5 × 10 19 m −2 s −1 is expected for its south polar region when Phaethon moves from 0 • to 2 • mean anomaly near perihelion. Consequently, dust particles with radii of <∼260 μm can be blown away to form a dust tail. In addition, we find that the large surface temperature variation of >600 K near perihelion can generate sufficiently large thermal stress to cause fracture of rocks or boulders and provide an efficient mechanism to produce dust particles on the surface. The timescale for this process should be several times longer than the seasonal thermal cycle, thereby dominating the cycle of appearance of the dust tail.

show abstract

A simple model for understanding the DIM dust measurement at comet 67P/Churyumov–Gerasimenko

Cited by 7 publications

References 14 publications

Seasonal erosion and restoration of the dust cover on comet 67P/Churyumov-Gerasimenko as observed by OSIRIS onboard Rosetta

Seasonal erosion and restoration of the dust cover on comet 67P/Churyumov-Gerasimenko as observed by OSIRIS onboard Rosetta

Synthesis of the morphological description of cometary dust at comet 67P/Churyumov-Gerasimenko

What mechanisms dominate the activity of Geminid Parent (3200) Phaethon?

Contact Info

Product

Resources

About