A model of the 3-μm hydration band with Exponentially Modified Gaussian (EMG) profiles: Application to hydrated chondrites and asteroids

1S.Potin,2S.Manigand,1,3P.Beck,1 C.Wolters,1B.Schmitt
Icarus (in Press) Link to Aricle [https://doi.org/10.1016/j.icarus.2020.113686]
1Université Grenoble Alpes, CNRS, IPAG, 414 rue de la Piscine, 38400 Saint-Martin d’Hères, France
2Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5–7, DK-1350 Copenhagen K., Denmark
3Institut Universitaire de France, Paris, France
Copyright Elsevier

We present here a new method to model the shape of the 3-μm absorption band in the reflectance spectra of meteorites and small bodies. The band is decomposed into several OH/H2O components using Exponentially Modified Gaussian (EMG) profiles, as well as possible organic components using Gaussian profiles when present. We compare this model to polynomial and multiple Gaussian profile fits and show that the EMGs model returns the best rendering of the shape of the band, with significantly lower residuals. We also propose as an example an algorithm to estimate the error on the band parameters using a bootstrap method. We then present an application of the model to two spectral analyses of smectites subjected to different H2O vapor pressures, and present the variations of the components with decreasing humidity. This example emphasizes the ability of this model to coherently retrieve weak bands that are hidden within much stronger ones.


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