The permanently shadowed regions of dwarf planet Ceres

Schörghofer, N.; Mazarico, E.; Platz, Thomas; Preusker, Frank; Schröder, Stefan; Raymond, C. A.; Russell, C. T.

doi:10.1002/2016gl069368

Cited by 61 publications

(49 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Presently, Ceres's obliquity is about 4° [ Russell et al , ]. Due to this low obliquity, permanently shadowed regions have been detected on Ceres's surface using the Dawn Framing camera images and shape‐based illumination modeling [ Schorghofer et al , ; Platz et al , ]. This makes Ceres only the third body in the solar system after the Moon [ Zuber and Smith , ; Mazarico et al , ] and Mercury [ Chabot et al , ; Neumann et al , ] with identified PSRs.…”

Section: Introductionmentioning

confidence: 99%

Ceres's obliquity history and its implications for the permanently shadowed regions

Ermakov

Mazarico

Schröder

et al. 2017

Geophysical Research Letters

View full text Add to dashboard Cite

Due to the small current obliquity of Ceres (ε≈4°), permanently shadowed regions (PSRs) exist on the dwarf planet's surface. Since the existence and persistence of the PSRs depend on the obliquity, we compute the obliquity history over the last 3 Myr and find that it undergoes large oscillations with a period of 24.5 kyr and a maximum of εmax≈19.6°. During periods of large obliquity, most of the present‐day PSRs receive direct sunlight. Some craters in Ceres's polar regions possess bright crater floor deposits (BCFDs). We find an apparent correlation between BCFDs and the most persistent PSRs. In the north, only two PSRs remain at εmax and they both contain BCFDs. In the south, one of the two only craters that remain in shadow at εmax contains a BCFD. The location of BCFDs within persistent PSRs strongly suggests that BCFDs consist of volatiles accumulated in PSR cold traps: either water molecules trapped from the exosphere or exposed ground ice.

show abstract

Section: Introductionmentioning

confidence: 99%

Ceres's obliquity history and its implications for the permanently shadowed regions

Ermakov

Mazarico

Schröder

et al. 2017

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Schorghofer et al (2016) have illustrated these temperatures for Ceres. At current obliquity, 4°, CO 2 , SO 2 , and NH 3 could be trapped in shallow PSRs near the rotational poles.…”

Section: Cold-trapping Of Icesmentioning

confidence: 99%

“…Table 2 shows the model results for various scenarios. The first row corresponds to an equatorial source of water molecules, within 40  , as was assumed in Section 3 and in Schorghofer et al (2016). The second row corresponds to a geographically uniform source, where a slightly higher fraction is captured, because launch velocities are lower at the more polar latitudes and the source is on average closer to the cold traps.…”

Section: Cold-trapping Of Icesmentioning

confidence: 99%

“…The dynamics of exospheres with an exobase has long been studied (e.g., Öpik and Singer 1959), but here a surface-bounded exosphere is considered. Tu et al (2014) and Schorghofer et al (2016) previously modeled the cerean water exosphere. The behavior of a denser water atmosphere on Ceres was modeled by Küppers et al (2014) and Formisano et al (2016).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Putative Cerean Exosphere

Schörghofer

Byrne

Landis

et al. 2017

ApJ

Self Cite

View full text Add to dashboard Cite

The ice-rich crust of dwarf planet 1 Ceres is the source of a tenuous water exosphere, and the behavior of this putative exosphere is investigated with model calculations. Outgassing water molecules seasonally condense around the winter pole in an optically thin layer. This seasonal cap reaches an estimated mass of at least 2 10 kg 3 , and the aphelion summer pole may even retain water throughout summer. If this reservoir is suddenly released by a solar energetic particle event, it would form a denser transient water exosphere. Our model calculations also explore species other than H 2 O. Light exospheric species escape rapidly from Ceres due to its low gravity, and hence their exospheres dissipate soon after their respective source has faded. For example, the theoretical turn-over time in a water exosphere is only 7 hr. A significant fraction of CO 2 and SO 2 molecules can get trapped and stored in perennially shadowed regions at the current spin axis orientation, but not at the higher spin axis tilt, leaving H 2 O as the only common volatile expected to accumulate in polar cold traps over long timescales. The D/H fractionation during migration to the cold traps is only about 10%.

show abstract

“…This is difficult to reconcile with the SEP hypothesis (Villarreal et al, ) as a sole source of the exosphere, as an SEP event would cause an isolated spike in vapor rather than continuous production necessary to maintain an exosphere in the time between the successive detections reported by Küppers et al (). Ultimately, most of the vapor around Ceres will be lost to space and a very small amount will end up in the persistently shadowed regions at the poles (e.g., Schörghofer et al, ).…”

Section: Introductionmentioning

confidence: 99%

Water Vapor Contribution to Ceres' Exosphere From Observed Surface Ice and Postulated Ice‐Exposing Impacts

et al. 2019

View full text Add to dashboard Cite

Telescopic observations have detected an exosphere around Ceres, composed of either water vapor or its photolytic products. Proposed mechanisms for its formation include sublimation or sputtering from solar energetic particles of buried ice, surface ice, or an optically thin seasonal polar cap. We estimate the amount of water vapor produced by known exposures of water ice, detected in Dawn spacecraft image and spectral data and by ice exposures from subresolution impact craters. We use thermal and sublimation modeling to take into account slope, orientation, and, in the case of water ice within craters, shadowing due to crater walls. We use a Monte Carlo approach to calculate the number of ice‐exposing impacts, where they occur on Ceres' surface, and how long the ice within the impact crater remains bright (e.g., less than one monolayer of sublimation lag). We find that the observed water ice patches on Ceres could account for ~0.06 kg/s of water vapor to (with Oxo crater as the main contributor) and that ice‐exposing impacts that remain bright in appearance after one Ceres year supply 0.08–0.56 kg/s of vapor, depending on the regolith volume fraction of the ice. While water ice has not been detected to date at Occator crater, if it were present we find that Occator is unlikely to be a major contributor of vapor. We find a typical background water vapor production rate from all of Ceres, combining surface and buried ice, of about a few tenths of a kilogram per second.

show abstract

The permanently shadowed regions of dwarf planet Ceres

Cited by 61 publications

References 55 publications

Ceres's obliquity history and its implications for the permanently shadowed regions

Ceres's obliquity history and its implications for the permanently shadowed regions

The Putative Cerean Exosphere

Water Vapor Contribution to Ceres' Exosphere From Observed Surface Ice and Postulated Ice‐Exposing Impacts

Contact Info

Product

Resources

About