In astronomy Westerhout 49 also known as W49, is a strong galactic thermal radio source characteristic of an HII region.

It has been compared to the giant HII region NGC 3603 which is about half as distant.

While this is partly due to interstellar absorption, any tight clustering of stars at such a great distance in the galactic plane would be scarcely distinguishable from the general background.

[citation needed] A study published in 2014, where the VLT has been used among other instruments, shows the presence of a very massive star in the central cluster of this star-forming region.

The parameters of said star (W49nr1, also known as [WBB2016] 1[2]) are so far poorly constrained, but a luminosity of several million times that of the Sun is estimated as well as an initial mass between 100 and 180 solar masses, and perhaps even more, what would place it among both the most luminous and massive stars known.