Artist impression of white dwarf. Credit: ESA/Hubble, NASA, S. Geier.
This week Texas astronomers are announcing a new discovery: that dying stars display massive outbursts as they decay. These hot, bright flashes haven’t been seen before in stars like these.
Almost all stars end up as white dwarfs, when they run out of the fuel that makes them shine. And as white dwarfs, these dying stars pulsate like a heartbeat: bright then dim, bright then dim.
“These stars vibrate. They ring, really like a bell, in a regular – a very regular – way,” says Keaton Bell, a graduate student at the University of Texas at Austin. Working with J.J. Hermes – now at the University of Warwick in England – Bell found something different happening with white dwarfs – an irregular heartbeat. “That regular rhythmic brightening and dimming that we observe is broken up with a fairly large outburst event, where the star gets very bright for many hours.”
To find this phenomenon required a dedication to observation. Bell explains, “This star was observed for more than 1-1/2 years, just pretty much continuously. The telescope stared unblinking at the same patch of sky.”
And to make this discovery, Bell and Hermes didn’t rely on earthbound tools. “We’re not getting data during the daytimes or when it’s cloudy from the ground. And so we may miss these rare events from traditional telescopes.”
It was from the telescope on the Kepler spacecraft that made the discovery possible. Bell says, “This discovery was enabled by the sheer amount of data that the Kepler spacecraft provided us.”
Bell and Hermes are publishing their findings in academic journals.