How do active asteroids such as 133P/Elst-Pizarro produce cometlike activity?

Active asteroids, such as 133P/Elst-Pizarro, are a group of small bodies located in the main asteroid belt that exhibit cometlike activity, such as the development of a coma or tail.1

While traditional asteroids are primarily composed of rock and metal and lack the volatile components necessary to produce such features, these "main-belt comets" behave differently. Their cometlike activity is driven by the presence of volatile ices—such as water ice—that sublimate when the object is warmed by the Sun. As these ices transform directly from a solid to a vapor, the escaping gas carries away embedded dust particles, creating the characteristic atmosphere and tail associated with comets.123

This suggests that despite their location in the asteroid belt, these objects retain volatile materials from the early solar system, similar to the icy bodies found in the Kuiper belt or Oort cloud.12