Hey Space Placers!
A team of astronomers has published a paper which states that there are asteroids in the asteroid belt that are really comets. Their paper details that 12 rocks came to life as comets thus the name for them - "Lazarus Comets".
It has been thought that some asteroids and some comets could be one in the same, defined only by the current state in which they exist. An asteroid could have the ingredients necessary to become a comet but for the lack of energy received from the Sun prevents its ices from evaporating. A comet could have been so active that it has evaporated off all of its cometary raw material to reveal bedrock.
Jupiter's gravity has a major role in jostling the asteroid belt so that these dead comets can come back to life by being moved closer to the Sun. The extra energy from the Sun begins the process of evaporating the ice and frozen gases from the surface of the former dead comet to form a live comet.
No one knows how many of these Lazarus Comets exist in the asteroid belt. Perhaps continued and improved observations of the asteroid belt can identify characteristics of these asteroid-comets or comet-asteroids if you prefer.
Read More About It: http://www.ras.org.uk/news-and-press/224-news-2013/2325-a-cometary-graveyard
I look forward to more research results.
Sky Guy in VA