Astronomers explain why a star is so hot right now »

Astronomers have solved a mystery over small, unusually hot blue stars, 10 times hotter than our Sun, that are found in the middle of dense star clusters. The international team found the so-called blue hook stars throw off their cool outer layers late in life because they are rotating so rapidly, making them more luminous than usual. "We've solved an old puzzle. These stars are only half the mass of our Sun yet we could not explain how they became so luminous," said team member Dr Antonino Milone, from ANU Research School of Astronomy and Astrophysics. "As the star was forming billions of years ago from a disc of gas in the congested centre of the star cluster, another star or stars must have collided with the disc and destroyed it." Star clusters are rare environments in the Universe, in which many stars are born at the same time. The team studied the globular cluster Omega Centauri, the only cluster visible to the naked eye, which contains around 10 million stars in close proximity to one another. The model shows the formation of stars in clusters do not all form at once, said co-author Dr Aaron Dotter, also from ANU Research School of Astronomy and Astrophysics.