This object does not fit into the known framework. What is a 2009 DQ118?

They provide very important support to astronomers, often relieving them of basic tasks related to observing the sky. They recently dealt with something that is neither a comet nor an asteroid. The results so far in this regard have been presented in: Astrophysical Journal Letters.

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These observations were made as part of the Active Asteroids project. Participants analyzed data from 2009 DQ118, looking for signs of comet-like behavior. This evidence was clear in images taken in March 2016, where signs of the comet’s tail could be seen.

However, this year’s observations showed an increase in activity as the object approaches the Sun. The problem is that sometimes asteroids can behave similarly. For example, the collision of two such meteorites may spew out dust, creating the characteristic cloud of comets. Sometimes asteroids can spin fast enough to eject material on their own.

2009 DQ118 is an object that moves in orbits similar to asteroids, but at the same time shows characteristics characteristic of comets.

2009 DQ118 challenges this framework, so astronomers are considering different scenarios. Maybe it’s a comet behaving like an asteroid. We also cannot rule out the scenario in which an unknown process is responsible for “activating” asteroids.

In the context of this kind of consideration, it is worth taking into account a concept such as the Hilda asteroid family. It moves in an orbit similar to Jupiter and remains in orbital resonance with it in a ratio of 3:2. This means that when the gas giant orbits the sun three times, it does so twice at the same time. About 5,000 of these objects are known to science, but it can be assumed that there are many more in reality.

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The 2009 DQ118, however, is not part of this family, although it can be considered a ‘quazihild’. But how can we distinguish between an asteroid and a comet? The very general assumption is that asteroids are rocky and comets are icy, although sometimes the composition of both is mixed. When ice turns into gas through sublimation, which may occur as the distance from the Sun decreases, such an object resembles a comet. Temperatures around Jupiter are much lower, so the ice remains icy.

So what is the answer to the question about the nature of 2009 DQ118? It is one of the major comets in the belt. Astronomers define them as objects moving in orbits similar to those of asteroids while exhibiting optical properties similar to those of comets. So far, so few major belt comets have been identified that each subsequent discovery is worth its weight in gold and is considered a valuable discovery for researchers who deal with them.