Westerhout 49-2

Westerhout 49-2 (W49-2) is a very massive and luminous star in the H II region Westerhout 49. At a mass of 250 solar masses (although with significant uncertainty) and a luminosity of over, it is one of the most massive and most luminous stars known.

Properties
Westerhout 49-2 is located within the H II region Westerhout 49, about 11.1 kiloparsecs from the Sun. The star is heavily reddened, and it is reddened in the K band by nearly 5 magnitudes, the most of any star in the region. Westerhout 49-2 is classified as an evolved slash star, with a spectral type of O2-3.5If*. The star is one of the most luminous stars known, with a luminosity of, and has a temperature of about 35,500 K, corresponding to a radius of over 55 times that of the Sun.

Uncertainties
There is significant uncertainty about Westerhout 49-2's properties. For example, its luminosity may be anywhere between and. Moreover, there is even greater uncertainty about its mass, which may be anywhere between, though it's more likely to be between 90 and 240 M☉.