KY Cygni is a variable red supergiant of spectral class M3Ia located in the constellation Cygnus. It is approximately 4,700 light-years away.

天鹅座KY距离地球约 5000 ly，半径约为 1420 R⊙，质量约为 25 M⊙，光度约为 1.38 × 10^5 ~ 2.73 × 10^5 L⊙。 天鹅座 KY 的大小可能被高估，因为其不寻常的 K 频和人为的发红校正错误。

2023年5月8日 · KY Cygni measures close to 1,033 times the width of the sun, according to a 2020 paper in the journal Astrophysics of Galaxies.

2024年8月8日 · KY Cygni is a red supergiant with an apparent magnitude of 10.87. It’s also a pulsating long-period variable star whose magnitude varies from 13.5 to 15.5. KY Cygni was discovered in 1930. Image Credit: Roy Britt / Space.com.

2005年2月3日 · The size of the star KY Cygni is shown in comparison to Betelgeuse, one of the largest stars previously known. KY Cygni has a diameter about 1,500 times larger than the sun.

2020年7月19日 · KY Cygni. 虽然KY Cygni至少是太阳半径的1420倍，但一些估计认为它更接近于2850倍太阳半径(尽管它可能更接近较小的估计)。KY天鹅座位于天鹅座，距离地球约5000光年。不幸的是，目前还没有这颗恒星的图像。 KW Sagittarii

KY Cygni is a red star in the Cygnus constellation. [1] It is one of the largest stars known [ 2 ] and with a radius about 1,420–1,503 R ☉ (6.60–6.99 au ). If it was placed at the center of the Solar System , it would extend past the orbit of Jupiter (or Saturn ).

2020年7月28日 · KY Cygni (KY Cyg) is a supergiant star in the constellation of Cygnus and one of the largest stars known. The star is thought to have a radius 1,420 times larger than the Sun's making it slightly smaller than the radius of the largest star known, UY Scuti, at 1,700 solar radii.

KY Cyg lies near the bright open cluster NGC 6913, but is not thought to be a member. The location is close to the bright star γ Cygni. It was identified as a variable star in 1930, and later named as KY Cygni. The spectrum was given the MK classification of M3 Ia, with only minor adjustments since.

KY Cygni The red supergiant belongs to the same category as VV Cephei and the Garnet Star. In contrast to these its gigantic diameter is undisputable. Maybe it is bigger than the both. Constellation: Cygnus Distance: 5200 light-years Spectral class: M4 Visual magnitude: 13.3 Luminosity: 300 000 * Sun Mass: circa 25 * Sun Diameter: 1500 * Sun