A First Taste of MEAD (Measuring Extinction and Abundances of Dust). I. Diffuse Milky Way Interstellar Dust Extinction Features in JWST Infrared Spectra
We present the initial results of the Measuring Extinction and Abundances of Dust project, with a focus on the dust extinction features observed in our JWST near- and mid-infrared spectra of nine diffuse Milky Way sightlines (1.2 ≤ A(V) ≤ 2.5). For the first time, we find strong correlations between...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/384897 |
| Acceso en línea: | http://hdl.handle.net/10261/384897 https://api.elsevier.com/content/abstract/scopus_id/85216356733 |
| Access Level: | acceso abierto |
| Palabra clave: | Dust composition Interstellar dust extinction Interstellar dust Silicate grains Carbonaceous grains Interstellar abundances Extinction http://astrothesaurus.org/uat/2271 http://astrothesaurus.org/uat/837 http://astrothesaurus.org/uat/836 http://astrothesaurus.org/uat/1456 http://astrothesaurus.org/uat/832 http://astrothesaurus.org/uat/201 http://astrothesaurus.org/uat/505 |
| Sumario: | We present the initial results of the Measuring Extinction and Abundances of Dust project, with a focus on the dust extinction features observed in our JWST near- and mid-infrared spectra of nine diffuse Milky Way sightlines (1.2 ≤ A(V) ≤ 2.5). For the first time, we find strong correlations between the 10 μm silicate feature strength and the column densities of Mg, Fe, and O in dust. This is consistent with the well-established theory that Mg- and Fe-rich silicates are responsible for this feature. We obtain an average stoichiometry of the silicate grains in our sample of Mg:Fe:O = 1.1:1:11.2, constraining the grain composition. We find variations in the feature properties, indicating that different sightlines contain different types of silicates. In the average spectrum of our sample, we tentatively detect features around 3.4 and 6.2 μm, which are likely caused by aliphatic and aromatic/olefinic hydrocarbons, respectively. If real, to the best of our knowledge, this is the first detection of hydrocarbons in purely diffuse sightlines with A(V) ≤ 2.5, confirming the presence of these grains in diffuse environments. We detected a 3 μm feature toward HD073882 and tentatively in the sample average, likely caused by water ice (or solid-state water trapped on silicate grains). If confirmed, to the best of our knowledge, this is the first detection of ice in purely diffuse sightlines with A(V) ≤ 2.5, supporting previous findings that these molecules can exist in the diffuse interstellar medium. |
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