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Recent replenishment of aliphatic organics on Ceres from a large subsurface reservoir

Cite this dataset

De Sanctis, Maria Cristina et al. (2024). Recent replenishment of aliphatic organics on Ceres from a large subsurface reservoir [Dataset]. Dryad. https://doi.org/10.5061/dryad.cnp5hqcdd

Abstract

Ceres hosts significant aliphatic-organic concentrations, ranging from approximately 5 wt.% to >30 wt.% in specific surface areas. The origins and persistence of these organics are under debate due to the intense aliphatic signature and radiation levels in Ceres' orbit, which would typically lead to their destruction, hindering detection. To investigate this, we conducted laboratory experiments to replicate how the signature of the organic-rich regions would degrade due to radiation. Our findings indicate a fast degradation rate, implying the exposure of buried organics within the last few million years. This degradation rate, coupled with observed quantities, implies that the aliphatics must be present in substantial quantities within the shallow subsurface. Our estimates suggest an initial aliphatic abundance 2-30 times greater than currently observed, surpassing significantly the levels found in carbonaceous chondrites, indicating either a significant concentration or remarkable purity.

README: Recent replenishment of aliphatic organics on Ceres from a large subsurface reservoir

https://doi.org/10.5061/dryad.cnp5hqcdd

Data set of figures of the article.

Description of the data and file structure

Text files (ascii) in table form with the physical units in the first line of the table.

Data fig.1: Spectrum of aliphatic rich pixels compared with an average spectrum of the Ernutet region taken by the VIR spectrometer.

Data in Fig.2 :  Energetic ion irradiation experiments were performed at INAF – Osservatorio Astrofisico di Catania (Italy). Three analogs in the form of compact pellets (named CU-1, CU-2, and CU-3) were irradiated under high vacuum at room temperature by 200 keV He+, N+, and H+ ions respectively. At selected fluences, samples were removed from the irradiation chamber and analised by means of diffuse reflectance IR spectroscopy at room pressure and temperature (see Material and Methods section). The data shows the  decrease of  the 3.4 µm feature of the CU-3 sample as prepared and after irradiation with 200 keV H+ at increasing fluences. 

Data in fig.3  show  the trend of  3.4 µm band area of Ceres’ analog samples as a function of irradiation dose after exposure to 200 keV H+, He+, and N+.  The data reported In Fig. 3A are  the normalised 3.4 µm band area  as a function of the dose for the three samples after irradiation with 200 keV He+, N+, and H+, respectively. 

Data of fig.4 show the estimated  Lifetime of the 3.4 µm band exposed to solar particle irradiation (100 keV – 1 GeV) at Ceres. Lifetime is estimated from OMERE simulations adopting the destruction cross section σ in units of 16u/eV obtained from the experimental data for three different porosity values. Dashed vertical lines show the estimated IR photons penetration depth in laboratory analogues (5 µm) and in the Ceres surface (about 100 µm). 

Data in fig.5 show* *Diffuse reflectance spectra of Ceres simulant sample in the range 3.24-3.68 µm at room temperature acquired during UV irradiation.

Data in fig.6  show  the  transmission spectra of the Ceres’ analog sample after continuum subtraction in the range 3.30-3.60 µm as produced and after hydrogen atom exposure for 3600 s and 18000 s; b)  evolution of the integrated optical depth of the aliphatic C-H modes with H atom exposure time.

Data in fig.7  show  the diffuse reflectance spectrum acquired at room temperature of the Ceres analogue sample. 

Data in fig.8 represent  the Residual fraction CH.  Residual fraction of CH bonds after exposure to SEP radiation as a function of depth for different porosity values (0.0, 0.5, and 0.9) and different irradiation time (0.1, 1, and 5 million years).

Methods

The data set show the modification of the 3.4 micron band under the influence of different energetic sources. the experiments have been conducted at INAF – Osservatorio Astrofisico di Catania (Italy); INAF – Osservatorio Astrofisico di Arcetri (Italy) and INAF – Osservatorio Astrofisico di Napoli(Italy)

 

Funding

Organic Material on Ceres, Award: 1.05.01.86.08 E