They have very low mass and emit their light mainly in the infrared, being invisible to the human eye.
Astrophysicists from Northwestern University and the University of California San Diego, both in the US, have identified the ultracold, low-mass binary stellar system with the shortest orbital period ever observed, they reported this week. The two stars are so close that the “year” of each is only 20.5 hours long.. The newly discovered system, which was dubbed ‘LP 413-53AB’, is also the oldest of all previously discovered systems.
Astronomers had only detected three ultracold dwarf binary systems with compact orbits, but the orbital period of LP 413-53AB is at least three times shorter than all those discovered so far. Likewise, these earlier systems are relatively young, up to 40 million years old. For its part, it is estimated that LP 413-53AB is billions of years old, making it the oldest ever detected.
“It’s exciting to discover such an extreme system,” said Chih-Chun ‘Dino’ Hsu, the Northwestern University astrophysicist who led the study. “In principle, we knew that these systems should exist, but such systems had not yet been identified,” he stressed.
something remarkably amazing
Examining the spectral data for LP 413-53AB, Hsu noticed something strange and realized that there were two stars locked in an incredibly compact binary. The team directed powerful telescopes towards the constellation Taurus, where the binary system is located, and made several observations.
“When we were doing this measurement, we could see things change within a couple of minutes of observing,” said UC San Diego professor Adam Burgasser. “Most of the binaries we track have orbit periods of years. So, you get a measurement every few months. Then after a while, you can put the puzzle together. With this system, we were able to see the spectral lines moving in real time.. It’s amazing to see something happen in the universe on a human time scale,” she explained.
no chance for life
The distance between the two stars is about 1% of the distance between the Earth and the Sun.. “This is remarkable because when they were young, at something like 1 million years old, these stars would have been on top of each other,” Burgasser said. Since the distance of the habitable zone is the same as the stellar orbit in LP 413-53AB, the formation of habitable planets in this system is impossible.