Westerlund 1 W75 or Wd 1-75 is a
red supergiant (RSG) located in the
Westerlund 1
Westerlund 1 (abbreviated Wd1, sometimes called Ara Cluster) is a compact young super star cluster about 3.8 kpc (12,000 ly) away from Earth. It is thought to be the most massive young star cluster in the Milky Way, and was discovered by Ben ...
super star cluster
A super star cluster (SSC) is a very massive young open cluster that is thought to be the precursor of a globular cluster. These clusters called "super" because they are relatively more luminous and contain more mass than other young star clusters. ...
. Its radius is calculated to be around 668
solar radii (4.65 × 10
8 km, 3.10
au). This corresponds to a volume 298 million times bigger than the
Sun. If placed at the center of the
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
, Westerlund 1-75 would engulf the inner limits of the
asteroid belt.
The star is classified as a luminous cool
supergiant emitting most of its energy in the
infrared spectrum
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
. 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.
See also
*
List of largest known stars
Below are lists of the largest stars currently known, ordered by radius and separated into categories by galaxy. The unit of measurement used is the radius of the Sun (approximately ).
The angular diameters of stars can be measured directly us ...
Notes
References
{{DEFAULTSORT:Westerlund 1-75
Ara (constellation)
M-type supergiants
J16470892-4549585
TIC objects