Gaia Sky comes with most of the mesh sets preinstalled.
Here are some resources for the galaxy map.
Python scripts for creating and selecting the meshes:
Gaia Sky key frame animator:
All map meshes set up in Blender with lighting and materials:
Gaia Sky meshes:
All but the two largest mesh sets (Non ionizing ranges ge25 lt50 and Non ionizing peaks ge25 lt50) are part of the normal Gaia Sky install.
Individual map meshes:
These are for use outside of Gaia Sky and are larger more detailed versions. As the hot star, dust and HII region meshes were created using different bin sizes and orientations, it probably makes sense to convert them to a standard coordinate system representing parsecs where the galactic centre (0 degrees) is to the right and the sun is at (0,0,0).
Here are the transformations:
hot star meshes: multiply mesh coordinates by 3, translate by (-3027,-2997,-597), rotate by -90 degrees
dust meshes: multiply mesh coordinates by 5, translate by (-2045,-1995,-300), rotate by -90 degrees
HII regions: no transformation should be necessary.