BD+05 4868Ab

Lore & Background

BD+05 4868Ab is an extreme case of a catastrophically evaporating planet. It currently has a mass similar to the Moon, but mass is being stripped off, forming long comet-like trails 9 million kilometers long behind and in front of it. These trails extend over half of the planet's orbit around the star. Dust grains found within the trails are 1–10 microns in size. It is thought that BD+05 4868Ab initially had a mass greater than Mercury, but over a time scale of several billion years, it lost that mass due to evaporation. The planet is one of four known disintegrating planets, along with Kepler-1520b, KOI-2700b, and K2-22b.

Reader's Guide

BD+05 4868Ab represents a rare and extreme class of exoplanets: disintegrating planets. Its significance lies in providing a direct observational window into planetary evaporation processes. The planet's dust trails, extending 9 million kilometers and covering over half its orbit, allow astronomers to study the composition and dynamics of material being lost from a planetary body. As one of only four known disintegrating planets, it serves as a key comparative object alongside Kepler-1520b, KOI-2700b, and K2-22b. The fact that BD+05 4868Ab likely started with a mass greater than Mercury and has been reduced to lunar mass over billions of years demonstrates the long-term effects of stellar irradiation on close-orbiting planets. Its discovery in 2025 via the transit method adds to the growing catalog of planets observed in the process of destruction, offering insights into planetary interiors and the fate of worlds orbiting too close to their stars.

Did You Know?

• BD+05 4868Ab is located 140 light years from Earth in the constellation Pegasus.
• The planet's dust trails extend 9 million kilometers and cover over half its orbit.