Evidence for the effects of space weathering spectral signatures on low albedo asteroids

Lantz, C.; Clark, B. E.; Barucci, Maria Antonella; Лауретта, Д. С.

doi:10.1051/0004-6361/201321593

Cited by 51 publications

(26 citation statements)

References 27 publications

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“…Since that work, however, it has been realized that there are several factors that may influence the shape of an asteroid spectrum that is not directly related to composition. Two examples are space weathering (Moroz et al 1996;Gaffey 2010;Lantz et al 2013;Miller et al 2014) and phase reddening (Sanchez et al 2012).…”

Section: Discussionmentioning

confidence: 99%

Characterizing spectral continuity in SDSSu′g′r′i′z′ asteroid photometry

Hasselmann

Fulchignoni

Carvano

et al. 2015

A&A

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Context. The 4th release of the SDSS Moving Object Catalog (SDSSMOC) is presently the largest photometric dataset of asteroids. Up to this point, the release of large asteroid datasets has always been followed by a redefinition of asteroid taxonomy. In the years that followed the release of the first SDSSMOC, several classification schemes using its data were proposed, all using the taxonomic classes from previous taxonomies. However, no successful attempt has been made to derive a new taxonomic system directly from the SDSS dataset. Aims. The scope of the work is to propose a different interpretation scheme for gauging u g r i z asteroid observations based on the continuity of spectral features. The scheme is integrated into previous taxonomic labeling, but is not dependent on them. Methods. We analyzed the behavior of asteroid sampling through principal components analysis to understand the role of uncertainties in the SDSSMOC. We identified that asteroids in this space follow two separate linear trends using reflectances in the visible, which is characteristic of their spectrophotometric features. Results. Introducing taxonomic classes, we are able to interpret both trends as representative of featured and featureless spectra. The evolution within the trend is connected mainly to the band depth for featured asteroids and to the spectral slope for featureless ones. We defined a different taxonomic system that allowed us to only classify asteroids by two labels. Conclusions. We have classified 69% of all SDSSMOC sample, which is a robustness higher than reached by previous SDSS classifications. Furthermore, as an example, we present the behavior of asteroid (5129) Groom, whose taxonomic labeling changes according to one of the trends owing to phase reddening. Now, such behavior can be characterized by the variation of one single parameter, its position in the trend.

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Section: Discussionmentioning

confidence: 99%

Characterizing spectral continuity in SDSSu′g′r′i′z′ asteroid photometry

Hasselmann

Fulchignoni

Carvano

et al. 2015

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“…Within this complex, the Ch-and Cgh-types are defined by the presence of an absorption band around 0.7 µm, and a UV-dropoff (sharper for the Cgh). These have been estimated to represent between 30% and 65% by number (Rivkin, 2012;Fornasier et al, 2014), and are associated with CM chondrites (namely the Ch-and Cgh-types, see Vilas et al, 1993;Burbine, 1998;Bus & Binzel, 2002;DeMeo et al, 2009;Lantz et al, 2013; Based on observations made with 1) ESO Telescopes at the La Silla Paranal Observatory under programs 281.C-5011 (PI Dumas), 099.D-0098 (SPHERE GTO), and 199.C-0074(A) (PI Vernazza); and 2) the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.…”

Section: Introductionmentioning

confidence: 99%

Homogeneous internal structure of CM-like asteroid (41) Daphne

Carry

Vachier

Berthier

et al. 2019

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Context. CM-like asteroids (Ch and Cgh classes) are a major population within the broader C-complex, encompassing about 10% of the mass of the main asteroid belt. Their internal structure has been predicted to be homogeneous, based on their compositional similarity as inferred from spectroscopy (Vernazza et al., 2016, AJ 152, 154) and numerical modeling of their early thermal evolution (Bland & Travis, 2017, Sci. Adv. 3, e1602514). Aims. Here we aim to test this hypothesis by deriving the density of the CM-like asteroid (41) Daphne from detailed modeling of its shape and the orbit of its small satellite. Methods. We observed Daphne and its satellite within our imaging survey with the Very Large Telescope extreme adaptive-optics SPHERE/ZIMPOL camera (ID 199.C-0074, PI P. Vernazza) and complemented this data set with earlier Keck/NIRC2 and VLT/NACO observations. We analyzed the dynamics of the satellite with our Genoid meta-heuristic algorithm. Combining our high-angular resolution images with optical lightcurves and stellar occultations, we determine the spin period, orientation, and 3-D shape, using our ADAM shape modeling algorithm. Results. The satellite orbits Daphne on an equatorial, quasi-circular, prograde orbit, like the satellites of many other large main-belt asteroids. The shape model of Daphne reveals several large flat areas that could be large impact craters. The mass determined from this orbit combined with the volume computed from the shape model implies a density for Daphne of 1.77 ±0.26 g·cm −3 (3 σ). This density is consistent with a primordial CM-like homogeneous internal structure with some level of macroporosity (≈17%). Conclusions. Based on our analysis of the density of Daphne and 75 other Ch/Cgh-type asteroids gathered from the literature, we conclude that the primordial internal structure of the CM parent bodies was homogeneous.

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“…Here we focus on the CM2 Murchison chondrite because of the well established link between the CM meteorites and the C-class asteroids (see, e.g., Burbine et al 2002). This meteorite also has a matrix that has undergone a certain degree of aqueous alteration (Buseck & Hua 1993) and the CM-class can be easily used to look for similarities with primitive asteroids (Lantz et al 2013;Fornasier et al 2014). Furthermore, we chose the Murchison meteorite to test the presence of the organic compounds after irradiation through the analysis of the aliphatic CH stretching bands at 3.4 µm, by analogy to what is observed on some C-class asteroids (e.g., 24 Themis, Campins et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Ion irradiation of the Murchison meteorite: Visible to mid-infrared spectroscopic results

Lantz

Brunetto

Barucci

et al. 2015

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Aims. The goal of this study is to simulate space weathering processes on primitive bodies. We use ion implantation as a simulation of solar wind irradiation, which has been suggested by several authors to be the major component of space weathering on main belt asteroids. The laboratory analogs we irradiate and analyze are carbonaceous chondrites; we started the study with the Allende CV meteorite and in this companion paper we present results on the Murchison CM meteorite. Methods. We performed irradiations on pressed pellets of Murchison with 40 keV He+ and Ar + ions using fluences up to 3 × 10 16 ions/cm 2 . Reflectance spectra were acquired ex situ before and after irradiation in the visible to mid-infrared range (0.4-16 µm). A Raman analysis was also performed to investigate the modifications of the aromatic carbonaceous component. Results. Our results indicate that spectral variations after irradiation within the visible range are smaller than spectral variations due to sample grain size or viewing geometry of the Murchison meteorite. The aqueous alteration band profile near 3 µm changes after irradiation, as adsorbed water is removed, and phyllosilicates are affected. Raman spectroscopy highlights the insoluble organic matter (IOM) modification under irradiation. We observe a shift of the silicates band at 9.9 µm, probably due to a preferential loss of Mg (compared to Fe, the lighter Mg is more easily sputtered backward) and/or amorphization of Mg-rich materials. We compare our results to previous experiments on organic-rich materials (like asphaltite or carbonaceous chondrites), and on ordinary chondrites and olivine grains. We find that the reddening/darkening trend observed on silicate-rich surfaces is not valid for all carbonaceous chondrites, and that the spectral modifications after irradiation are a function of the initial albedo.

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Evidence for the effects of space weathering spectral signatures on low albedo asteroids

Cited by 51 publications

References 27 publications

Characterizing spectral continuity in SDSSu′g′r′i′z′ asteroid photometry

Characterizing spectral continuity in SDSSu′g′r′i′z′ asteroid photometry

Homogeneous internal structure of CM-like asteroid (41) Daphne

Ion irradiation of the Murchison meteorite: Visible to mid-infrared spectroscopic results

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