Binary Dwarf Stars Found Orbiting Each Other Every 20 Hours. They Were Once Almost Touching

A team of astrophysicists has discovered a binary pair of ultra-cool dwarfs so close together that they look like a single star. They’re remarkable because they only take 20.5 hours to orbit each other, meaning their year is less than one Earth Day. They’re also much older than similar systems.

We can’t see ultra-cool dwarf stars with the naked eye, but they’re the most numerous stars in the galaxy. They have such low masses that they only emit infrared light, and we need infrared telescopes to see them. They’re interesting objects because theory shows stars this close together should exist, but this system is the first time astronomers have observed this extreme proximity.

“It’s amazing to see something happen in the universe on a human time scale.”

Professor Adam Burgasser, UC San Diego.

A team of astronomers presented their findings at the 241st Meeting of the American Astronomical Society in Seattle. Chih-Chun “Dino” Hsu, an astrophysicist at Northwestern University, led the research. The system is named LP 413-53AB.