Astronomers study a new and unique typology of asteroids: cometary asteroids . Unlike other typologies, active asteroids show one or more tails whose origin they are trying to reveal. Of the more than 750,000 asteroids discovered to date, only a few dozen are in this category.
The investigations carried out in recent years by a group of astronomers led by Javier Licandro and Fernando Moreno from the Instituto de Astrofísica de Canarias (IAC) and Andalucía (IAA), respectively, focus on determining what are the causes that are causing the appearance of this characteristic so characteristic in some asteroids.
Another aspect of interest is its origin. Are they cometary in nature or are they “common” asteroids originating in the Main Belt region? Whatever the answer, these objects have been called active asteroids , although because of their similarity to comets they are also known as “Main Belt comets.”
The first active asteroid discovered in 1996 was 7968 Elst-Pizarro . Its detection aroused the interest of astrophysicists and since then research has been carried out to better understand the nature of these unique objects.
The scientific value of these asteroids is that they can provide information about the processes of fragmentation and debris production , as well as the presence of ice in their interior; or perhaps they can offer information about the internal structure of these bodies.
It has been hypothesized that these unique objects originate from cometary orbits and that they were captured in some regions of the Main Belt of asteroids during the early stages of the formation of the Solar System. Although there is also the possibility that they had their origin in the Main Belt itself and that certain processes are causing the sublimation of particles, recreating behind them a tail similar in appearance to that of comets.
In the studies carried out by the IAC and the IAA, they have focused on the analysis of some of the recently discovered active asteroids. In total, they have analyzed twelve objects using images obtained with the Gran Telescopio de Canarias and the OSIRIS camera / spectrograph. The contrast of the high resolution images compared to the images generated with numerical models has made it possible to recreate the circumstances that could be causing the ejection of material .
Among the causes of these detachments of material would be the excessive speed of rotation of some asteroids that would cause the instability of the internal structure, which could lead to the fracture of the asteroid. Thermal disintegration would be another cause . The forces caused by the thermal expansion of the materials would cause cracks in the asteroid with the consequent production of dust and rock debris.
In previous studies carried out by the Instituto de Astrofísica de Canarias, it was suggested that asteroids composed of hydrated minerals could undergo a process of dehydration and sublimation of water.
Asteroids are relics of the different stages of the formation of the solar system and their study contributes to understanding the accretion processes that gave rise to the origin and evolution of our planetary system as we know them today.
Amadeo Aznar
APT Observatories Group
Aras Rural
