MSCA MWGaiaDN PhD position: Digging for the spiral arms through interstellar extinction and young stars

Interstellar dust is mainly concentrated in the Galactic plane, along the spiral arms, where young stars are being born. The dust modifies the light that reaches us from the stars: it absorbs it and reddens it. Knowing the 3D distribution of the extinction not only allows us to trace the spiral arms but also to derive the intrinsic light of the stars, which is essential for studying their astrophysical parameters such as their age. The European space mission Gaia is revolutionising our knowledge of our Galaxy by providing astrometric, photometric and spectroscopic data for more than one billion stars. The aim of the thesis is to extract extinction information from Gaia spectrophotometry, newly available with the 3rd release of Gaia data, combined with 2MASS near-infrared photometry. This will allow an update of the extinction map of Lallement et al. (2022). An optimised selection of young stars can be achieved simultaneously. This will enable the study of the similarities between the 3D position of the interstellar extinction and the young stars, with the aim of tracing the spiral arms (Gaia Collaboration, Drimmel et al. 2022). Using the young star velocities measured by Gaia together with maps of gaz emission line velocities, kinematic information will be added to the 3D view of the spiral arms.

This PhD project is part of the MWGaiaDN MSCA Doctoral Network. The network consists of 10 academic partners across Europe at which 12 PhD students will be active in the network researching a range of topics with Gaia and other data.