Highly Embedded 8 μm cores of Star Formation in the Spiral Arms and Filaments of 15 Nearby Disk Galaxies
Bruce G. Elmegreen and Debra Meloy Elmegreen 2019 ApJS 245 14
Spitzer Space Telescope observations of 15 spiral galaxies show numerous dense cores at 8 μm that, with a possible age between 0.2 and 2 Myr, likely represent the earliest phase for most star formation in these galaxies.