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J/A+A/609/A22       Interstellar dust through the Fe K-edge   (Rogantini+, 2018)

Investigating the interstellar dust through the Fe K-edge. Rogantini D., Costantini E., Zeegers S.T., de Vries C.P., Bras W., de Groot F., Mutschke H., Waters L.B.F.M. <Astron. Astrophys. 609, A22 (2018)> =2018A&A...609A..22R (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics ; Interstellar medium ; X-ray sources Keywords: X-rays: ISM - astrochemistry - dust, extinction - X-rays: binaries Abstract: The chemical and physical properties of interstellar dust in the densest regions of the Galaxy are still not well understood. X-rays provide a powerful probe since they can penetrate gas and dust over a wide range of column densities (up to 1024cm-2). The interaction (scattering and absorption) with the medium imprints spectral signatures that reflect the individual atoms which constitute the gas, molecule, or solid. In this work we investigate the ability of high resolution X-ray spectroscopy to probe the properties of cosmic grains containing iron. Although iron is heavily depleted into interstellar dust, the nature of the Fe-bearing grains is still largely uncertain. In our analysis we use iron K-edge synchrotron data of minerals likely present in the ISM dust taken at the European Synchrotron Radiation Facility. We explore the prospects of determining the chemical composition and the size of astrophysical dust in the Galactic centre and in molecular clouds with future X-ray missions. The energy resolution and the effective area of the present X-ray telescopes are not sufficient to detect and study the Fe K-edge, even for bright X-ray sources. From the analysis of the extinction cross sections of our dust models implemented in the spectral fitting program SPEX, the Fe K-edge is promising for investigating both the chemistry and the size distribution of the interstellar dust. We find that the chemical composition regulates the X-ray absorption fine structures in the post edge region, whereas the scattering feature in the pre-edge is sensitive to the mean grain size. Finally, we note that the Fe K-edge is insensitive to other dust properties, such as the porosity and the geometry of the dust. Description: We analysed a sample of six silicates and two iron sulfides. The two iron sulfides have different origins. The pyrrothite was synthesised in the laboratory at Astrophysikalisches Institut und Universitaets-Sternwarte (AIU), whereas the troilite has a meteoritic origin. The data presented in this paper (except metallic iron) were measured at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 71 8 List of samples in our set with their relative chemical formulae sample/* 64 8 *Individual files for extinction, scattering and absorption cross section
Note on sample/*: Header included 3 rows: - Compound name and chemical formula - Units - Column labels
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1 I1 --- Seq Sequential number 3- 13 A11 --- Name Name (1) 15 A1 --- n_Name Note on Name (2) 17- 43 A27 --- For Chemical formula 45- 55 A11 --- State State 57- 71 A15 --- FileName Name of the file in subdirectory sample
Note (1): The nomenclature En(x)Fs(x-1) reveals the fraction of iron (or magnesium) included in the compound; 'En' stands for enstatite (the magnesium end-member of the pyroxene silicate mineral series, MgSiO3) and 'Fs' for ferrosilite (the respective iron end-member, FeSiO3) Note (2): Origin of elements as follows: a = origin Sri Lanka b = synthesised in laboratories at AIU Jena and Osaka University c = meteoritic origin d = origin: Paul Island, Labrador
Byte-by-byte Description of file (# headlines): sample/*
Bytes Format Units Label Explanations
8- 16 F9.7 keV Energy Energy around the Fe K-edge 20- 32 E13.7 cm+2/H Ext Extinction cross section 36- 48 E13.7 cm+2/H Sca Scattering cross section 52- 64 E13.7 cm+2/H Abs Absorption cross section
Acknowledgements: Daniele Rogantini, d.rogantini(at)sron.nl
(End) Patricia Vannier [CDS] 12-Dec-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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