These Dying Stars Have Erratic ‘Heartbeats’

August 27, 2015 Updated: September 1, 2015

Astronomers using the planet-hunting spacecraft Kepler have discovered a dying star with irregular pulsations that cause the star to get a few percent brighter and fainter every few minutes.

They also observed massive outbursts every few days that significantly heated up its surface for many hours.

The star, a white dwarf called PG1149+057, is in the constellation Virgo, which is roughly 120 light years from Earth. Our sun will eventually become a white dwarf in more than 6 billion years, after it runs out of its nuclear fuel.

“We have essentially found rogue waves in a pulsating star, akin to ‘irregular heartbeats.’ These were truly a surprise to see: We have been watching pulsating white dwarfs for more than 50 years now from the ground, and only by being able to stare uninterrupted for months from space have we been able to catch these events,” said JJ Hermes of the University of Warwick’s Astrophysics Group, who led the project.

15 Percent Brighter in an Hour




“These are highly energetic events, which can raise the star’s overall brightness by more than 15 percent and its overall temperature by more than 750 degrees in a matter of an hour,” said Hermes. “For context, the sun will only increase in overall brightness by about 1 percent over the next 100 million years.”

Not the Only Star



“The theory of stellar pulsations has long failed to explain why pulsations in white dwarfs stop at the temperature we observe them to,” argues Keaton Bell of the University of Texas at Austin, who analyzed the first pulsating white dwarf to show an irregular heartbeat, KIC 4552982.


What’s Going On?


“Ultimately, this may be a new type of nonlinear behavior that is triggered when the amplitude of a pulsation passes a certain threshold, perhaps similar to rogue waves on the open seas here on Earth, which are massive, spontaneous waves that can be many times larger than average surface waves,” said Hermes. “Still, this is a fresh discovery from observations, and there may be more to these irregular stellar heartbeats than we can imagine yet.”

The research appears in the Astrophysical Journal Letters.

This article was published by the University of Warwick in the U.K. Republished via under Creative Commons License 4.0.