Astronomers have discovered the largest yellow star ever observed in our galaxy, the Milky Way, which is 1,300 times larger than our sun and about 1 million times brighter than it, according to measurements made with a Very Large Telescope Interferometer of the European Southern Observatory in Paranal, Chile.
This hypergiant star called HR 5171 located at a distance of about 12,000 light-years from Earth in the Centaurus constellation, belonged also among the 10 largest stars known in the Milky Way.
HR 5171 is 50% larger than the famous supergiant Betelgeuse, said Olivier Chesneau (Observatoire de la Côte d’Azur, Nice, France), a member of the international team of the astronomers who made the discovery.
“The new observations have revealed that this huge yellow star has a very close companion, a smaller star, together they form a binary star system”, said the same astronomer.
Yellow supergiant stars are very rare – only 10 have been discovered in our galaxy ( e.g Rho Cassiopeiae). They are belong to the biggest and brightest stars in the sky and are at a stage of their existence when they are unstable and rapidly changing. The result of this instability: yellow supergiant expel material into space forming a vast atmosphere around them.
Despite the fact that it is far from Earth, about 12,000 light years (one light year is 9.46073 million billion miles), the star HR 5171 can be seen with the naked eye.
Over the last 40 years, the star has grown in size and cooled, and this evolution could be recorded by the scientists, Only a few stars are caught in this short phase of their existence.
For the latest monitoring of the star HR 5171, astronomers used a technique called interferometry, which is combine the light collected from multiple individual telescopes.