EXPLODING STARS have helped astronomers to discover one of the greatest mysteries of science, acting like a time machine to help us understand why the universe is spreading out at an accelerating rate, a Harvard professor says.
Prof Bob Kirshner, the Clowes Professor of Science at Harvard, was in Dublin yesterday to give two talks about the mysterious substance known as dark energy.
“We do not understand what this is. We really have no deep understanding of it,” he said before his talk last night at the Science Gallery at Trinity College.
Yet it represents one of the most important forces in the universe, given its ability to stretch out space and cause stars and galaxies to move away from one another at an accelerating rate.
Despite its central role, astronomers were unaware of dark energy until 1998 when the first scientific papers about it began to be published. Prof Kirshner was involved from the earliest days and has studied dark energy since.
He described how exploding stars, supernovas, were used by astronomers as beacons that can give information about distance and time. “We can see into the past in a kind of time machine,” he said. It was while studying these beacons that astronomers learned something was making stars accelerate away faster than they should have. “We found the supernovas were a little bit further away than we expected,” he said.
Studies since have convinced scientists that the effects are real; a kind of “anti-gravity” is pushing the universe apart, he said. The challenge now was to understand the force responsible for this.
An Irish amateur astronomer discovered a new star when looking for something else, writes Ronan McGreevy .
Dave McDonald was trying to find asteroids when he noticed the light from a known star had dimmed, making it a variable star.
He had discovered a companion star passing in front of the one he was looking at, and causing its light to fade. The two stars together are known as eclipsing binaries. Our Sun is a solitary star, making it an exception, as most stars have at least one companion.
The discovery has been confirmed by the American Association of Variable Star Observers, which has given the discovery the unwieldy designation VSX J012426.9+084154. Mr McDonald, one of most successful amateur Irish astronomers, is one of only a few Irish people with an asteroid named after them.