The Lifetime of Ice on Main Belt Asteroids

Schörghofer, N.

doi:10.1086/588633

Cited by 182 publications

(189 citation statements)

References 31 publications

(24 reference statements)

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“…Each row corresponds to a tilt angle between the object's rotation axis and its orbital plan. The Bond albedo is 2% and the thermal inertia at the surface is 3 J K −1 m −2 s −1/2 consistent with the results obtained by Schorghofer (2008) on the survival of water ice, and suggest that a detailed analysis needs to be performed for constraining the survival of minor volatile species.…”

Section: Thermal Processing and Ice Survivalsupporting

confidence: 84%

“…However, given the small number of MBCs and the different individual cases, both scenarios have to be taken into account. Schorghofer (2008) studied the survival of water ice inside asteroids, assumed to be spherical icy objects on orbits ranging from 2 to 3.3 au from the Sun. They introduced the concept of the 'buried snowline', i.e., the limit beyond which subsurface water ice can be sustained for the age of the Solar System inside asteroids.…”

Section: Family Originsmentioning

confidence: 99%

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The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies.

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Section: Thermal Processing and Ice Survivalsupporting

confidence: 84%

Section: Family Originsmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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“…Any ice buried under a dusty crust does not sublimate freely, but follows a diffusion regime where gas escapes through the crust. The mass loss rate from such a buried layer can be written as (assuming an ideal gas law, (Fanale & Salvail 1984;Schorghofer 2008;Gundlach et al 2011;Guilbert-Lepoutre 2014):…”

Section: Dusty Crust At the Surface Of 67pmentioning

confidence: 99%

Pre-perihelion activity of comet 67P/Churyumov-Gerasimenko

Guilbert-Lepoutre

Schulz

Rożek

et al. 2014

A&A

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Context. Comets are believed to hold a relatively pristine record of the physical and chemical processes that occurred during the formation and evolution of the solar system. Thorough investigations of these small bodies, such as the one that will be performed by the ESA/Rosetta cornerstone mission, are thus supposed to bring strong and unique constraints on the origins of the solar system. Aims. Because comet 67P/Churyumov-Gerasimenko was only recently selected as the target for the ESA/Rosetta mission, there has been little opportunity to study its pre-perihelion activity. This phase is, however, very important for the mission, since the global mapping of the nucleus and the choice of landing site for Philae will be performed during this pre-perihelion phase. Here, we report previously unpublished data of the last pre-perihelion passage of this comet, observed between May and September 2008. Methods. The gas and dust activity of comet 67P/Churyumov-Gerasimenko are studied through visible spectroscopy and broadband imaging, respectively, covering a range of pre-perihelion heliocentric distances between 2.99 and 2.22 AU. Results. The data we have gathered on the dust activity are consistent with trends observed by other authors and show a strong asymmetry between the pre-and post-perihelion phases of the orbit. The spectra do not show any lines due to the emission of volatiles, and upper limits on their production rates are typically one order of magnitude lower than at the equivalent post-perihelion heliocentric distances. The asymmetry in the pre-and post-perihelion phases of the activity may be due to a dusty crust quenching the activity at the surface of 67P. We estimate that this crust could be about 12 cm thick, although not uniform across the surface. Even if no gas is individually detected, the coma surface brightness profiles might indicate a possible contamination from gaseous species emitted before the comet actually reaches perihelion.

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“…In the above analysis, all asteroids in a given target category are assumed to be dormant MBCs, but in truth, the extent of this dormant population is unconstrained, except that it must assuredly be larger than the active population. In fact, if recent thermal and dynamical models are correct, the population of dormant MBCs could, in principle, span the entire main belt (Schorghofer 2008;Levison et al 2009). …”

Section: Mbc Population Sizementioning

confidence: 99%

The Hawaii trails project: comet-hunting in the main asteroid belt

Hsieh

2009

A&A

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Context. The mysterious solar system object 133P/(7968) Elst-Pizarro is dynamically asteroidal, yet displays recurrent comet-like dust emission. Two scenarios were hypothesized to explain this unusual behavior: 1) 133P is a classical comet from the outer solar system that has evolved onto a main-belt orbit or 2) 133P is a dynamically ordinary main-belt asteroid on which subsurface ice has recently been exposed. If 1) is correct, the expected rarity of a dynamical transition onto an asteroidal orbit implies that 133P could be alone in the main belt. In contrast, if 2) is correct, other icy main-belt objects should exist and could also exhibit cometary activity. Aims. Believing 133P to be a dynamically ordinary, yet icy main-belt asteroid, I set out to test the primary prediction of the hypothesis: that 133P-like objects should be common and could be found by an appropriately designed observational survey. Methods. I conducted just such a survey -the Hawaii Trails Project -of selected main-belt asteroids in a search for objects displaying cometary activity. Optical observations were made of targets selected from among the Themis, Koronis, and Veritas asteroid families, the Karin asteroid cluster, and low-inclination, kilometer-scale outer-belt asteroids, using the Lulin 1.0 m, small and moderate aperture research telescope system (SMARTS) 1.0 m, University of Hawaii 2.2 m, southern astrophysical research (SOAR) 4.1 m, Gemini North 8.1 m, Subaru 8.2 m, and Keck I 10 m telescopes. Results. I made 657 observations of 599 asteroids, discovering one active object now known as 176P/LINEAR, leading to the identification of the new cometary class of main-belt comets (MBCs). These results suggest that there could be ∼100 currently active MBCs among low-inclination, kilometer-scale outer-belt asteroids. Physically and statistically, MBC activity is consistent with initiation by meter-sized impactors. The estimated rate of impacts and sizes of resulting active sites, however, imply that 133P-sized bodies should become significantly devolatilized over Gyr timescales, suggesting that 133P, and possibly the other MBCs as well, could be secondary, or even multigenerational, fragments from recent breakup events.

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The Lifetime of Ice on Main Belt Asteroids

Cited by 182 publications

References 31 publications

The Main Belt Comets and ice in the Solar System

The Main Belt Comets and ice in the Solar System

Pre-perihelion activity of comet 67P/Churyumov-Gerasimenko

The Hawaii trails project: comet-hunting in the main asteroid belt

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