UY Scuti


UY Scuti is a red supergiant (RSG) star. It is a pulsating variable star in the constellation Scutum and one of the largest known stars in the Milky Way Galaxy. It is also one of the most luminous and well-known of its kind.[1][2]

The star has an estimated average median radius of 1,708 times that of the Sun, or a diameter of 2.4 trillion m (1.5 billion mi; 15.9 AU); thus a volume 5 billion times that of the Sun.

It is about 2.9 kiloparsecs (9,500 light years) from Earth, so it is one of the nearest known hypergiants.[3] If placed at the center of the Solar system, its photosphere would engulf the orbit of Jupiter. The radius is not known for certain, and may be larger than the orbit of Saturn.


  1. International Variable Star Index. "Detail for UY Sct". [1]
  2. Arroyo-Torres B. et al 2013. The atmospheric structure and fundamental parameters of the red supergiants AH Scorpii, UY Scuti, and KW Sagittarii. Astronomy & Astrophysics 554: A76. [2]
  3. Jura M. & Kleinmann S.G. 1990. Mass-losing M supergiants in the solar neighborhood. The Astrophysical Journal Supplement Series 73: 769. [3]