Loredana Prisinzano
INAF-Osservatorio Astronomico di Palermo
ABSTRACT
The ESA Gaia mission has transformed our understanding of the Milky Way through
high-precision astrometry, surveying about 1% of the Galaxy. However, observations at optical wavelengths cannot probe regions heavily obscured by interstellar dust.
A future GaiaNIR mission, operating in the near-infrared, would extend Gaia's capabilities by mapping obscured regions and intrinsically red objects, surveying approximately 25% of the Galaxy (more than 50 billion stars) with significantly improved astrometric accuracy. Planned for launch around 2045, GaiaNIR is being developed as a candidate ESA L-class mission within the Voyage 2050 programme, supported by the establishment of an international GaiaNIR consortium.
For star-forming regions, GaiaNIR will open a new parameter space by extending high-precision astrometry into the near-infrared, where extinction has so far limited Gaia's capabilities. It will provide the first homogeneous census of embedded young stellar objects, including the low-mass population that dominates the stellar initial mass function, allowing unbiased membership determination even in highly obscured environments. The combination of accurate parallaxes, proper motions, and multi-band NIR photometry will enable studies of the earliest phases of cluster formation, internal kinematics, cluster survival, and disk evolution across different environments. On Galactic scales, GaiaNIR will reveal the youngest stellar populations throughout the Galactic plane, allowing the spatial and dynamical connection between embedded clusters, molecular clouds, filaments, and large-scale star-forming structures to be investigated, ultimately providing fundamental constraints on the mechanisms driving star formation and the assembly of the Milky Way.