This graphic shows the relative size of the Sun, upper left, compared to the two stars in the binary system known as Wolf-Rayet 140, or WR 140. The O-type star is roughly 30 times the mass of the Sun, while its companion is about 10 times the mass of the Sun.

O-type stars are some of the biggest and brightest stars in the universe. They use up their fuel quickly and live relatively short lives – no more than about 10 million years, as opposed to stars like our Sun, which live for about 10 billion years.

Wolf-Rayet stars were once O-type stars that are now nearing the end of their lives. They release huge amounts of mass into space via stellar winds, exposing their hot, inner layers. The Wolf-Rayet star in WR 140 may have shed more than half its original mass. It has an estimated temperature of 60,000 Kelvin (about 110,000 degrees Fahrenheit, or about 60,000 degrees Celsius) – more than 10 times the temperature of our Sun. The temperature of the O-type star is about 35,000 Kelvin (about 63,000 F, or about 35,000 C).