Westerlund 1-75

Westerlund 1 W75 or Wd 1-75 is a red supergiant located in the Westerlund 1 super star cluster. Its radius is calculated to be around 668 solar radii. This corresponds to a volume 298 million times bigger than the Sun. If placed at the center of the Solar System, Westerlund 1-75 would engulf the inner limits of the asteroid belt.
Image:Comparison of Radii of RSGs located in the Westerlund 1 star cluster.png|300px|thumb|left|Westerlund 1-75 compared to the other 3 RSGs in the Westerlund 1 star cluster.
The star is classified as a luminous cool supergiant emitting most of its energy in the infrared spectrum. It occupies the upper right corner of the Hertzsprung-Russell diagram. Using the effective temperature of 3,600 K, the bolometric luminosity of 68,000 L_☉ and the solar effective temperature of 5,772 K, the radius of Westerlund 1-75 can be calculated using the Stefan-Boltzmann law at.
Like Westerlund 1-20, Westerlund 1 W26 and Westerlund 1-237, Westerlund 1-75 was observed to be a radio source, however it is weakest along the RSGs in its cluster and remains unresolved at any wavelength.
Westerlund 1-75 is surrounded by extended nebula, although it appears less massive than nebulae around typical red supergiant stars.