8 Pistol Star

The mysterious supernova

Hidden from view by a cloak of interstellar dust, the Pistol Star is a very mysterious object. Observed by Hubble in the 1990s, this highly luminous blue hypergiant is 25,000 light years from Earth, close to the Milky Way’s centre. In just 20 seconds the Pistol Star radiates as much energy as our Sun does in an entire year.

At the time of its birth it is thought to have already attained somewhere around 200 solar masses, although much of this was lost in a sequence of violent eruptions. These ejected upwards of ten solar masses of expanding gaseous material in a pair of titanic outbursts some 4,000 and 6,000 years ago. With a current radius over

300 times that of the Sun, the Pistol Star is currently thought to be about 27.5 times as massive.

It will continue to lose material until its core is exposed. By burning a figurative candlestick at both ends – its surface temperature is 11,527 degrees Celsius (20,780 degrees Fahrenheit) – the Pistol Star will meet a rapid, fiery end in a supernova within 3 million years. Alternatively it might end its days as a super-luminous ‘hypernova’, which could serve as a progenitor of long-duration gamma-ray bursts.