Describing their observations in the Monthly Notices of the Royal Astronomical Society, the astronomers said such enriched material in the space between stars is necessary for forming planetary systems.
A collaboration of scientists from Britain, Chile, Germany and the United States searching our galaxy for ejected material from evolved stars said they made a remarkable discovery while observing a super star cluster dubbed Westerlund 1, the most massive cluster of stars in our galaxy.
Around one of the stars, known as W26, they saw a huge cloud of glowing hydrogen gas; such clouds are rarely found around massive stars and are even rarer around red supergiant stars such as W26, they said.
The researchers realized the star is probably the largest star ever discovered, with a radius 1500 times larger than the Sun.
It is also one of the most luminous red supergiants known, they said.
Such large and luminous massive stars are believed to be highly evolved, suggesting W26 is coming towards the end of its life and will eventually explode as a supernova, astronomers said.