Ambient and cold‐temperature infrared spectra and XRD patterns of ammoniated phyllosilicates and carbonaceous chondrite meteorites relevant to Ceres and other solar system bodies

Ehlmann, B. L.; Hodyss, Robert; Bristow, T. F.; Rossman, George R.; Ammannito, E.; Sanctis, M. C. De; Raymond, C. A.

doi:10.1111/maps.13103

Cited by 36 publications

(36 citation statements)

References 45 publications

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“…These absorptions are most straightforwardly interpreted as due to ammoniated minerals, like those of Ceres are interpreted by de Sanctis et al (). Ehlmann et al () report absorptions throughout this range in spectra of smectites that were ammoniated in the laboratory, attributing the variation in wavelength to the degree of hydrogen bonding of NH 4 ‐H 2 O complexes.…”

Section: Analysis and Resultsmentioning

confidence: 99%

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Infrared Spectroscopy of Large, Low‐Albedo Asteroids: Are Ceres and Themis Archetypes or Outliers?

2019

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Low‐albedo, hydrated objects dominate the list of the largest asteroids. These objects have varied spectral shapes in the 3‐μm region, where diagnostic absorptions due to volatile species are found. Dawn's visit to Ceres has extended the view shaped by ground‐based observing and shown that world to be a complex one, potentially still experiencing geological activity. We present 33 observations from 2.2 to 4.0 μm of eight large (D > 200 km) asteroids from the C spectral complex, with spectra inconsistent with the hydrated minerals we see in meteorites. We characterize their absorption band characteristics via polynomial and Gaussian fits to test their spectral similarity to Ceres, the asteroid 24 Themis (thought to be covered in ice frost), and the asteroid 51 Nemausa (spectrally similar to the CM meteorites). We confirm most of the observations are inconsistent with what is seen in meteorites and require additional absorbers. We find clusters in band centers that correspond to Ceres‐ and Themis‐like spectra, but no hiatus in the distribution suitable for use to simply distinguish between them. We also find a range of band centers in the spectra that approaches what is seen on Comet 67P. Finally, variation is seen between observations for some objects, with the variation on 324 Bamberga consistent with hemispheric‐level difference in composition. Given the ubiquity of objects with 3‐μm spectra unlike what we see in meteorites, and the similarity of those spectra to the published spectra of Ceres and Themis, these objects appear much more to be archetypes than outliers.

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Section: Analysis and Resultsmentioning

confidence: 99%

“…Sub-Earth and subsolar coordinates for the Hygiea observations are available from the DAMIT website (Durech et al, 2010). There is no correlation seen between Gaussian fit band center and longitude, though there is a moderate correlation for longer-wavelength bands to be found at more positive latitudes.…”

Section: Variation On Objectsmentioning

confidence: 99%

Infrared Spectroscopy of Large, Low‐Albedo Asteroids: Are Ceres and Themis Archetypes or Outliers?

2019

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“…In contact with liquid water, NH 3 forms NH 4 + , which exchanges readily with univalent cations in clays, especially smectites, but not with serpentine (Ehlmann et al. ). This substitution could have occurred in a cooler environment nearer the surface (Castillo‐Rogez et al.…”

Section: Rationalizing the Differencesmentioning

confidence: 99%

Carbonaceous chondrites as analogs for the composition and alteration of Ceres

McSween

Emery

Rivkin

et al. 2017

Meteorit & Planetary Scien

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The mineralogy and geochemistry of Ceres, as constrained by Dawn's instruments, are broadly consistent with a carbonaceous chondrite (CM/CI) bulk composition. Differences explainable by Ceres's more advanced alteration include the formation of Mgrich serpentine and ammoniated clay; a greater proportion of carbonate and lesser organic matter; amounts of magnetite, sulfide, and carbon that could act as spectral darkening agents; and partial fractionation of water ice and silicates in the interior and regolith. Ceres is not spectrally unique, but is similar to a few other C-class asteroids, which may also have suffered extensive alteration. All these bodies are among the largest carbonaceous chondrite asteroids, and they orbit in the same part of the Main Belt. Thus, the degree of alteration is apparently related to the size of the body. Although the ammonia now incorporated into clay likely condensed in the outer nebula, we cannot presently determine whether Ceres itself formed in the outer solar system and migrated inward or was assembled within the Main Belt, along with other carbonaceous chondrite bodies.

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“…; Ehlmann et al. ), whereas the 3.3–3.5 μm feature, when observed in conjunction with a 3.95–4.0 μm absorption band, has been definitively attributed to carbonates (Rivkin et al. ; De Sanctis et al.…”

Section: Introductionmentioning

confidence: 98%

Mineralogy and temperature of crater Haulani on Ceres

Tosi

Carrozzo

Raponi

et al. 2018

Meteorit & Planetary Scien

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We investigate the region of crater Haulani on Ceres with an emphasis on mineralogy as inferred from data obtained by Dawn's Visible InfraRed mapping spectrometer (VIR), combined with multispectral image products from the Dawn Framing Camera (FC) so as to enable a clear correlation with specific geologic features. Haulani, which is one of the youngest craters on Ceres, exhibits a peculiar "blue" visible to nearinfrared spectral slope, and has distinct color properties as seen in multispectral composite images. In this paper, we investigate a number of spectral indices: reflectance; spectral slopes; abundance of Mg-bearing and NH 4 -bearing phyllosilicates; nature and abundance of carbonates, which are diagnostic of the overall crater mineralogy; plus a temperature map that highlights the major thermal anomaly found on Ceres. In addition, for the first time we quantify the abundances of several spectral endmembers by using VIR data obtained at the highest pixel resolution (~0.1 km). The overall picture we get from all these evidences, in particular the abundance of Na-and hydrous Na-carbonates at specific locations, confirms the young age of Haulani from a mineralogical viewpoint, and suggests that the dehydration of Na-carbonates in the anhydrous form Na 2 CO 3 may be still ongoing.

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Ambient and cold‐temperature infrared spectra and XRD patterns of ammoniated phyllosilicates and carbonaceous chondrite meteorites relevant to Ceres and other solar system bodies

Cited by 36 publications

References 45 publications

Infrared Spectroscopy of Large, Low‐Albedo Asteroids: Are Ceres and Themis Archetypes or Outliers?

Infrared Spectroscopy of Large, Low‐Albedo Asteroids: Are Ceres and Themis Archetypes or Outliers?

Carbonaceous chondrites as analogs for the composition and alteration of Ceres

Mineralogy and temperature of crater Haulani on Ceres

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