 Frost line (astrophysics)

In astrophysics, the "frost line" (also known as the "snow line") refers to a specific region in a protoplanetary disk, located at a certain distance from the central star, where temperatures drop low enough for volatile compounds—such as water, ammonia, and methane—to condense into solid ice. Inside this line, the temperatures are too high for these materials to freeze, while beyond this line, they can exist in solid form.