The Very Large Telescope complex of the Southern Space Observatory (ESO), made up of four reflector telescopes and an interferometer, has revealed the existence of an enormous star, which measures 1,300 times the diameter of the Sun, and is a million times larger. sparkly. It is one of the ten largest stars discovered so far , surpassing even the famous red supergiant Betelgeuse, and the largest yellow star on record. Therefore, despite the great distance that separates it from Earth (about 12,000 light years), the star can be seen with the naked eye.
Observations revealed that the star HR 5171 has been progressively growing and cooling over the past 40 years. It is also part of an eclipsing binary system in which a small star revolves around a larger star. In this case, the minor star completes its orbit around HR 5171 every 1,300 days, and has a slightly higher surface temperature (5,000ºC). To draw these conclusions, the astronomers collated the data collected through a technique called interferometry, which combines the light collected by optical telescopes to recreate a giant telescope of more than 140 meters, with observations carried out by amateurs throughout sixty years.
Yellow hypergiants are a very rare class of stars, being in a very early stage of their evolution, characterized by variations in their apparent luminosity and in their surface temperature. Only a dozen of them are known in our galaxy, among which Rho Cassiopeiae stands out, one of the largest and brightest documented to date. These celestial bodies undergo periodic eruptions in which they expel material to the outside, forming a large and extended atmosphere around them.
This new discovery shows the importance of studying short-lived giant stars, since this information could help us understand the evolutionary processes of massive stars in general.
