Pluto’s “heart”, also known as “Tombaugh Regio”, is filled with nitrogen ice, which reflects more light than its surroundings. In addition, this region is “depressed” into the dwarf planet’s surface by an average of three kilometres.
“The elongated shape of the structure strongly suggests that the collision was not direct, but most likely at an acute angle. We recreated many such events by varying both the composition of the objects and the force, velocity and angle of impact,” the study authors explained.
According to the modelling, given that Pluto is very cold, the rocky fragments of the 730-kilometre-long impactor did not melt, but remained solid, despite releasing large amounts of heat on impact. And thanks to the angle, about 30 degrees, and the low speed of impact, they did not sink into the dwarf planet’s core, but remained relatively intact close to the surface, with the ice brought in quickly filling the resulting basin.
