If that sounds like beating hearts, that’s because it is — in a way. It’s the sound of “heartbeat” stars. If you plot how the light from such a star changes, it looks like an EKG — like a beating heart. Scientists have converted some of those beats to sound, and sped them up to show the rhythm of the heartbeats.

The stars are actually binaries — pairs of stars locked in orbit around each other. Their orbits are stretched out — they’re long and thin. Depending on the system, each orbit takes a few days to a few weeks, so the system “beats” at up to a few times per month.

When the two stars are at their closest, the gravity of each star distorts the shape of the other, making the stars bulge toward each other. That creates more surface area for both stars, making the system brighter. At the same time, the surfaces of the stars vibrate like ringing bells. That also changes their brightness.

Astronomers have discovered about 1300 heartbeat systems. Most of them consist of stars that are bigger, brighter, and more massive than the Sun. Such stars are more likely to be born in pairs than Sun-like stars are.

Several heartbeat systems are in Cygnus. The swan’s brightest star, Deneb, is high in the east-northeast as night falls, and passes almost directly overhead later on — surrounded by stars that produce their own heartbeats.
 

Script by Damond Benningfield