Le 29 janvier 2016
De 10h30 à 12h00
Mirel BIRLAN
IMCCE, Observatoire de Paris
M4AST (Modelling for asteroids) is a tool devoted to model and interpret spectra data in the visible and near-infrared of asteroids. It is composed by an asteroid spectral database and a set of applications for analyzing asteroid spectra. These applications cover aspects related to taxonomy, curve matching with laboratory spectra, space weathering models, and mineralogical diagnosis. Spectra data were obtained using groundbased facilities; part of these data are precompiled. One of the techniques used to characterize the surface of asteroids is reflectance spectroscopy in the visible and near-infrared wavelength regions. Diagnostic features in spectra related to electronic and vibrational transitions within minerals or molecules are detectable in the 0.35–2.50μm spectral range. The overlapping of the absorption bands from different mineral species provides a distinctive signature of the asteroid surface. Olivine, pyroxene (clino- and ortho-pyroxene), iron-nickel (Fe-Ni) metal, spinel, and feldspar are some of the most important minerals that can be identified by carefully analyzing the reflection spectra of the asteroid. M4AST database contains permanent and temporary files. Each permanent file contains a header and two or three columns (wavelength, spectral reflectance and the error on spectral reflectance). Temporary files could be uploaded by the anonymous users while they will get access to the computing routines. The computing routines are organized in order to accomplish several scientific objectives: visualize spectra, compute the asteroid taxonomic class, compare an asteroid spectra with similar spectra of meteorites, computing mineralogical parameters. M4AST is under permanent development. The database contains now more than 6,000 spectra of asteroids. The new improvements are the following:
– a new web-interface was designed with new functionalities into a user-friendly environment.
– a bridge system of access and exploiting the database SMASS- MIT (http://smass.mit.edu) of asteroids
– more than 6,000 spectra accessible into the permanent database M4AST