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Distribution 3D d'étoiles et de poussière dans le disque de la Voie Lactée

Abstract : We aim to study the structures of dust and stars of the Galactic disk thanks to large star surveys. With its second Data Release (GDR2), the Gaia satellite brings a huge number of parallaxes; however, the parallax precision degrades with distance and with extinction. And it is in the galactic disc that the dust is most present. It is then mandatory to associate near-infrared photometry, less sensible to extinction, and use statistical method to infer photometric distances.We therefore combined GDR2 Gaia astrometry with the 2MASS, UKIDSS and VVV infrared photometric catalogues, which we analysed using a Bayesian field of view analysis, FEDReD (Field Extinction - Distance Relationship Deconvolver). This algorithm makes it possible to obtain the relationship between extinction and distance in a given field of view, and also estimates the stellar density with distance.Applying FEDReD to the entire Galactic disk, we obtained an extinction density map. FEDReD can trace extinction and stellar density to a distance of about 5 kpc for crowded fields, and up to 10 kpc for the least dense fields.At small distances, FEDReD is able to confirm the presence and shape of several known extinction structures, such as the split of the local arm, the Vela cloud, or the spiral arm of the scutum, which are all detected using other methods. In addition, FEDReD improves the extinction map at larger distances by highlighting the extension of some of the known structures, and in fine improves our understanding of the Milky Way disk.
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Clément Hottier. Distribution 3D d'étoiles et de poussière dans le disque de la Voie Lactée. Astrophysique [astro-ph]. Université Paris sciences et lettres, 2019. Français. ⟨NNT : 2019PSLEO003⟩. ⟨tel-02879238⟩

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