Scientists hit "rewind" to discover how white dwarfs play a role in the evolution of a supernova.
Astronomers have found the first direct evidence that some star explosions are triggered by compact stars called white dwarfs.
Scientists studying the youngest type of Ia supernova ever found worked backward to pinpoint its explosion time with unparalleled accuracy. In doing so, they confirmed that a white dwarf was the source of the blast, and gleaned insights into the nature of the dwarf's companion star.
The discovery occurred in August, when astronomer Peter Nugent spotted a surprising object while poring over data from the Palomar Transit Survey's robotic telescope at Palomar Observatory in Southern California. The object was quickly confirmed to be a type Ia supernova. High-resolution follow-up observations were made within hours by the Keck telescope in Mauna Kea, Hawaii, identifying the elements that burst from the blast.
The speedy response allowed Nugent and his team to follow the evolution of the supernova, called SN 2011fe. [Amazing Photos of Supernova Explosions]
As the light of the explosion reached the brightness of 2.5 billion suns, then slowly faded, the team worked backward to determine exactly when the supernova occurred. Located only 21 million light-years from Earth in the Pinwheel Galaxy, the supernova is the closest one to our planet in 25 years. (A light-year is the distance light travels in a year, about 6 trillion miles, or 10 trillion kilometers.)