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

S. Potin, S. Manigand, P. Beck, C. Wolters, B. Schmitt

In Press, Journal Pre-proof, Available online 7 February 2020


• Exponentially Modified Gaussians are used to model the shape of the 3-μm band.
• The band is deconvoluated into several OH-group carriers.
• This model returns significantly reduced residuals compared to other fits.
• It allows a precise analysis of variations detected using spectroscopy.
• The errors on the model can be calculated using a statistical bootstrap method.”


“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.”