The formation of high-mass stars remains one of the most significant unsolved problems in all of astrophysics. These stars, with masses greater than 8-10 solar masses, eventually explode as supernovae and produce most of the heavy elements in the universe. Observations of HII regions produced by massive stars are a prime tool for extragalactic astronomers to determine the star formation rate and abundances in galaxies. Despite the importance of massive star formation, relatively little is known about it. Massive star forming sites are rare and thus tend to be farther from Earth than low-mass star forming regions.
Observations therefore demand high spatial resolution.
Massive star formation occurs in clusters with high stellar densities, so even greater resolution is required to avoid confusion. In addition, massive stars destroy their natal environment via HII regions. Much of what we do know comes from observations of ultracompact HII regions that become visible only after star formation is nearly complete. The massive stars' radiation is heating the nebula, causing it to glow, and will eventually destroy it. Massive star formation also poses major theoretical challenges.