Titre :

Low-temperature MIR to submillimeter mass absorption coefficient of interstellar dust analogues II. Mg and Fe-rich amorphous silicates

Auteur(s) :

Demyk, Karine [Auteur]
Institut de recherche en astrophysique et planétologie [IRAP]
Meny, C. [Auteur]
Institut de recherche en astrophysique et planétologie [IRAP]
Leroux, Hugues [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Depecker, Christophe [Auteur]
Unité Matériaux et Transformations - UMR 8207 [UMET]
Brubach, J.-B. [Auteur]
Synchrotron SOLEIL [SSOLEIL]
Roy, P. [Auteur]
Synchrotron SOLEIL [SSOLEIL]
Nayral, C. [Auteur]
Laboratoire de physique et chimie des nano-objets [LPCNO]
Ojo, W.-S. [Auteur]
Laboratoire de physique et chimie des nano-objets [LPCNO]
Delpech, F. [Auteur]
Laboratoire de physique et chimie des nano-objets [LPCNO]

Titre de la revue :

Astronomy and Astrophysics - A&A

Numéro :

606

Pagination :

A50

Date de publication :

2017

Discipline(s) HAL :

Planète et Univers [physics]/Astrophysique [astro-ph]
Physique [physics]/Matière Condensée [cond-mat]/Science des matériaux [cond-mat.mtrl-sci]
Physique [physics]/Astrophysique [astro-ph]
Planète et Univers [physics]/Sciences de la Terre
Chimie/Matériaux
Physique [physics]/Physique [physics]/Géophysique [physics.geo-ph]

Résumé en anglais : [en]

Context. To model the cold dust emission observed in the diffuse interstellar medium, in dense molecular clouds or in cold clumps that could eventually form new stars, it is mandatory to know the physical and spectroscopic ...
Lire la suite >Context. To model the cold dust emission observed in the diffuse interstellar medium, in dense molecular clouds or in cold clumps that could eventually form new stars, it is mandatory to know the physical and spectroscopic properties of this dust and to understand its emission. Aims. This work is a continuation of previous studies aiming at providing astronomers with spectroscopic data of realistic cosmic dust analogues for the interpretation of observations. The aim of the present work is to extend the range of studied analogues to iron-rich silicate dust analogues. Methods. Ferromagnesium amorphous silicate dust analogues were produced by a sol-gel method with a mean composition close to Mg1−xFexSiO3 with x = 0.1, 0.2, 0.3, 0.4. Part of each sample was annealed at 500 °C for two hours in a reducing atmosphere to modify the oxidation state of iron. We have measured the mass absorption coefficient (MAC) of these eight ferromagnesium amorphous silicate dust analogues in the spectral domain 30−1000 μm for grain temperature in the range 10−300 K and at room temperature in the 5−40 μm range. Results. The MAC of ferromagnesium samples behaves in the same way as the MAC of pure Mg-rich amorphous silicate samples. In the 30−300 K range, the MAC increases with increasing grain temperature whereas in the range 10−30 K, we do not see any change of the MAC. The MAC cannot be described by a single power law in λ− β. The MAC of the samples does not show any clear trend with the iron content. However the annealing process has, on average, an effect on the MAC that we explain by the evolution of the structure of the samples induced by the processing. The MAC of all the samples is much higher than the MAC calculated by dust models. Conclusions. The complex behavior of the MAC of amorphous silicates with wavelength and temperature is observed whatever the exact silicate composition (Mg vs. Fe amount). It is a universal characteristic of amorphous materials, and therefore of amorphous cosmic silicates, that should be taken into account in astronomical modeling. The enhanced MAC of the measured samples compared to the MAC calculated for cosmic dust model implies that dust masses are overestimated by the models.Lire moins >

Langue :

Anglais

Comité de lecture :

Oui

Audience :

Internationale

Vulgarisation :

Non

Établissement(s) :

Université de Lille
ENSCL
CNRS
INRA

Collections :

• Unité Matériaux et Transformations (UMET) - UMR 8207

Équipe(s) de recherche :

Matériaux Terrestres et Planétaires

Date de dépôt :

2019-05-16T17:21:19Z
2021-02-16T08:21:15Z