Scientists have discovered a record-breaking binary star system consisting of two ultra-cold dwarf stars very close together, orbiting each other in less than a day. The stars are only separated by about 1.5 million miles, about 1% of the distance from Earth. And by the sun that means For these stars, a year takes only 17 hours. This makes the star system the densest supercold dwarf binary ever found.

Couple systemLabeled LP 413–53AB and located in the constellation TaurusIt was discovered by Northwestern University and UC San Diego astrophysicists using the WM Keck Observatory, located at the foot of the extinct Maunakea volcano in Hawaii.

“This is an exciting discovery of such an extreme system,” said Chi-Chun “Dino” Hsu, a team leader and astrophysicist at Northwestern University.. “We knew, in principle, that these systems should exist, but no such system had yet been described.”

Ultracool dwarfs are one of the most common types of stars in the universe. Universe, but these low-mass stars are so cold that most of the light they emit is in the form of infrared light. This means they are invisible to the human eye and difficult to detect. Short-period binary systems of these stars are even rarer.

Prior to the discovery of LP 413-53AB, astronomers had discovered only three extremely cold dwarf binary systems with short-period orbits, each less than 40 million years old, almost a baby compared to our 4.6 billion-year-old Sun. On the other hand, the team estimates that LP 413-53AB is much older than stars in previously known systems, several billion years old, and much closer to the age of this Sun. The system’s orbital period is about four times shorter than the orbital period of the densest of the ultracold dwarf binary systems previously discovered.

The team first discovered this record-breaking duo while probing archival data when they noticed something strange in the light spectrum from the Hsu LP 413-53AB. Early observations captured a binary system when the stars aligned, meaning their spectral data matched and mixed with a single star. The spectral lines then diverged and moved in opposite directions as the stars continued to orbit, suggesting Xu was actually looking at two stars. The astrophysicist also realized that these stars must have been locked in a very close binary system.

Researching this discovery with the Keck Observatory’s Near Infrared Spectrograph (NIRSPEC), Hsu and his team made several observations of the system between March 2022 and January 2023. These observations confirmed Hsu’s prediction that the distance between stars was about 1.48 million miles.