AB Pic b sits right at the boundary between a planet and a brown dwarf, an object too small to shine as a star. It orbits AB Pic, a young star a little cooler than the Sun about 160 light-years away, very far out: a 2023 study puts its orbit at about 190 times Earth's distance from the Sun.
A team led by G. Chauvin found it in 2005 in deep infrared images, as a faint red point 5.5 arcseconds from the star. Images at two more times showed it moving with the star rather than being a distant background object, and a spectrum classed it as an early L-type object. Because the system is young, about 30 million years old, the team estimated from its brightness a mass of 13 to 14 Jupiter masses, right at the dividing line often used between planets and brown dwarfs, and asked directly whether it is a massive planet or a minimum-mass brown dwarf.
In 2023 a team led by P. Palma-Bifani combined spectra and images collected over two decades. They found its temperature about 1,700 kelvin and, for the first time, measured the ratio of carbon to oxygen in its atmosphere, which is close to the Sun's. It spins once every 2.1 hours, and its spin axis appears tilted relative to its orbit, by about 45 or 135 degrees. They also found that the star's slight shift in position, measured by the Hipparcos and Gaia satellites, points to a possible second planet of about 6 Jupiter masses much closer in, which still needs confirming.