Space-Weathering of Solar System Bodies: A Laboratory Perspective

Bennett, Chris J.; Pirim, Claire; Orlando, Thomas M.

doi:10.1021/cr400153k

Cited by 153 publications

(110 citation statements)

References 727 publications

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“…A complication with these considerations is that, while a 3-micron absorption band has been detected on Pallas, the irradiation and the heating reduce and completely remove the 3-micron band, respectively (see e.g. Bennett et al 2013).…”

Section: Discussionmentioning

confidence: 99%

Differences between the Pallas collisional family and similarly sized B-type asteroids

Alí-Lagoa

Licandro

Gil-Hutton

et al. 2016

A&A

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Context. B-type asteroids constitute a peculiar spectral class within the C-complex. Previous work has pointed out the difference between the visible geometric albedos of B-types and those of the Pallas collisional family (PCF), whose few members with observed spectra are B-types (one exception out of eight objects). This has been interpreted as being due to compositional differences. However, the PCF members are typically smaller than the spectroscopically classified B-types, and the following possibilities have not been ruled out: the albedo differences might be related to a size-albedo dependence and/or to the generally larger errors of the WISE data and best-fitting values of the derived parameters expected for smaller objects. Aims. We compare albedos and beaming parameters of PCF members and B-types of similar sizes and re-examine our conclusion on the different composition of the PCF. Methods. By modelling their WISE/NEOWISE data, we derived sizes and albedos of all objects whose Sloan Digital Sky Survey reflectances are similar to the typical B-type reflectance spectra. In particular, we derived the so-called infrared beaming parameters (η), effective diameters (D), and corresponding visible geometric albedos (p V ), and studied their value distributions. Results. We obtained the effective diameter and geometric visible albedo for ∼600 B-type asteroids whose sizes range between 2 and 100 km, approximately half of which have fitted η-values that are inversely correlated to size. We found that the albedo distributions of the PCF is significantly different from that of other B-types in the same size range (2−20 km), and we rule out any size-albedo dependency or biases related to the lower quality of the p V -values of smaller objects. In addition, we also found differences between the η-value distribution of the PCF and the other similarly-sized B-types. Conclusions. The differences in the visible albedos of PCF members and the other B-types of similar sizes is a strong indication that their compositions are different. The trend between beaming parameter and size of the B-types (excluding the PCF) is consistent with the expectation that the surfaces of smaller asteroids have coarser rocks than do those of larger objects (D > 40 km), which are thought to be covered by a finer, more insulating layer of dust.

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Section: Discussionmentioning

confidence: 99%

Differences between the Pallas collisional family and similarly sized B-type asteroids

Alí-Lagoa

Licandro

Gil-Hutton

et al. 2016

A&A

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“…All studied ices were submitted to the same fluence of electron energy ∼2×10 21 eV cm −2 . Radiation fluences were scaled to the outer-solar system based on the electron flux at 1 au, which was deduced from values given in Bennett et al (2013). We found that the total fluence received by our ice samples corresponds to a timescale of 0.2 Myr for an object at 5 au and 1.8 Myr at 15 au.…”

Section: Experimental Methodologymentioning

confidence: 99%

Production of Sulfur Allotropes in Electron Irradiated Jupiter Trojans Ice Analogs

Mahjoub

Poston

Blacksberg

et al. 2017

ApJ

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In this paper, we investigate sulfur chemistry in laboratory analogs of Jupiter Trojans and Kuiper Belt Objects (KBOs). Electron irradiation experiments of CH 3 OH-NH 3 -H 2 O and H 2 S-CH 3 OH-NH 3 -H 2 O ices were conducted to better understand the chemical differences between primordial planetesimals inside and outside the sublimation line of H 2 S. The main goal of this work is to test the chemical plausibility of the hypothesis correlating the color bimodality in Jupiter Trojans with sulfur chemistry in the incipient solar system. Temperature programmed desorption (TPD) of the irradiated mixtures allows the detection of small sulfur allotropes (S 3 and S 4 ) after the irradiation of H 2 S containing ice mixtures. These small, red polymers are metastable and could polymerize further under thermal processing and irradiation, producing larger sulfur polymers (mainly S 8 ) that are spectroscopically neutral at wavelengths above 500 nm. This transformation may affect the spectral reflectance of Jupiter Trojans in a different way compared to KBOs, thereby providing a useful framework for possibly differentiating and determining the formation and history of small bodies. Along with allotropes, we report the production of organosulfur molecules. Sulfur molecules produced in our experiment have been recently detected by Rosetta in the coma of 67P/Churyumov-Gerasimenko. The very weak absorption of sulfur polymers in the infrared range hampers their identification on Trojans and KBOs, but these allotropes strongly absorb light at UV and Visible wavelengths. This suggests that high signal-to-noise ratio UV-Vis spectra of these objects could provide new constraints on their presence.

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“…In a recent review of the space weathering of solar system bodies, Bennett et al (2013) report the available data on the mass flux of dust on the surfaces of several objects in the solar system (see their Table 3). While those fluxes are not known for objects in the Jupiter system, they are available for the Saturnian and Uranian systems.…”

Section: Implication For Molecular Formation and Erosion Of Solid Carmentioning

confidence: 99%

A laboratory study of ion-induced erosion of ice-covered carbon grains

Sabri

Baratta

Jäger

et al. 2015

A&A

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Context. It has been confirmed that solid carbon dioxide (CO 2 ) is abundantly present along the line of sight to quiescent clouds and star-forming regions via space IR observations with ISO-SWS and Spitzer Space Telescope. Since CO 2 has low abundance in the gas-phase, the assumption is that it is synthesized on grains after energetic processing of icy mantles and surface reactions. Aims. The role of solid carbon is investigated as a reservoir for molecule formation and structural modifications of the material with and without an ice layer upon ion bombardment. Methods. A gas-phase condensation technique was used to prepare a layer of 13 C amorphous grains. These grains were covered with H 2 O and O 2 ice and finally bombarded with 200 keV protons. The formation of new molecular species was analyzed using IR spectroscopy. The formation cross sections of solid 13 CO and 13 CO 2 were determined from the increase in the column density as a function of the fluence. In addition, bare carbon grains were bombarded with a comparable fluence of protons to study the processing of the grains without ice layer. Imaging techniques such as transmission electron microscopy were used to monitor the changes in the structure. Results. CO and CO 2 were formed efficiently at the interface between ice and solid carbon grains at the expense of solid carbon, leading to strong grain erosion. Given the initial thickness of our C-samples (about 120 nm), this resulted in an erosion of about 50% after 200 keV proton bombardment with 6.76 × 10 16 ions/cm 2 . The column density of CO and CO 2 follows an exponential trend as a function of the irradiation fluence. The asymptotic values obtained when O 2 ice is deposited on top of the carbon grains are about one order of magnitude higher than the values obtained when H 2 O ice is deposited on the solid carbon layer. The carbon grains were strongly graphitized upon ion bombardment in a surface layer. Less graphitization accompanied by the formation of fullerene molecules and structures from cage fragments present in the original material were observed beneath the graphitic layer. Conclusions. The formation of CO and CO 2 at the expense of solid carbon strongly restricts the lifetime of the solid carbon material and may influence the formation of more complex molecules in astrophysical environments. Graphitization of carbonaceous grains upon ion bombardment affect the spectral properties of the carbon grains in particular in the far-IR range.

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Space-Weathering of Solar System Bodies: A Laboratory Perspective

Cited by 153 publications

References 727 publications

Differences between the Pallas collisional family and similarly sized B-type asteroids

Differences between the Pallas collisional family and similarly sized B-type asteroids

Production of Sulfur Allotropes in Electron Irradiated Jupiter Trojans Ice Analogs

A laboratory study of ion-induced erosion of ice-covered carbon grains

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