Scientists Identified Four Incredibly Young Asteroid Families

Scientists Identified Four Incredibly Young Asteroid Families

Researchers went back in time to the asteroid formation era through numerical simulation and found some young asteroid families.

The minor planets, particularly of the inner solar system, are called asteroids. Initially, this term was used to describe all the sun-orbiting astronomical objects that didn’t fulfill the criteria of being a planet. The definition of an asteroid changed over time as astronomers got assistance from advanced technology and differentiated celestial objects like meteoroids and comets. Scientists are quite keen to keep a close look at the surrounding asteroids because an Asteroid Strike can lead to some disastrous results. The researchers at the São Paulo State University (UNESP) recently found four families of extremely young asteroids through a numerical simulation method. Valerio Carruba, a Professor of Mathematics at the UNESP, explained their work in the following words:

We identified the new families by means of numerical simulation using the backward integration method (BIM), which is much more precise than other methods for dating asteroid families. But BIM only works for really young families that are less than 20 million years old. Until recently, only eight families had been studied by this method. We now know 13, almost a third of which were identified by our group.

All of these four families were found in the Main Asteroid Belt which lies between Mars and Jupiter. The longitudes of the pericenter and ascending node were the key parameters which allowed the researchers to determine the age of these asteroid families. It was observed that all of them are less than 7 million years old. The term ‘Pericenter’ refers to a point at which the orbiting asteroid, comet, or planet comes closest to the Sun in case of an elliptical orbit. On the other hand, the Ascending Node is the point at which the orbit crosses the southern side of a reference plane to a northern side. Carruba explained that to the world by saying,

When an asteroid family is formed, all the asteroids’ pericenters and ascending nodes are aligned, but as the family evolves, the alignment is lost owing to gravitational disturbances produced by planets and possibly by some massive asteroids. Based on current data, BIM lets you go back in time using numerical simulation to reconstruct the setting in which the parameters were aligned and thereby date the asteroid family.”    

The study described that there are two possible ways through these asteroid families are born. The first one of them is the fission of a precursor body. It involves the ejection of the matter by a precursor body either because it recently expelled a secondary body that broke up or it acquired an extremely rapid rotation on its own axis. Contrary to that, these families are also formed as a result of a collisional event. The researchers examined a total of 59 new families (55 were detected by other scientists) and came up with a considerable precise diagram which differentiates between families formed by fission and by the collisional event. Carruba mentioned that one of the families they discover did form as a result of a collision by saying,

One of the four families we identified was undoubtedly formed by a collisional event. Collision is very likely to have been the origin of another. The rest were identified very recently, and we need more studies to formulate a hypothesis regarding their formation.

The number of asteroids in the Main Asteroid Belt is increasing continuously due to the introduction of improved methods of detection. According to an estimate, this number could go up to a million. Carruba mentioned that the distribution of these asteroids in the Main Belt is far from even. The complex gravitational interaction between numerous bodies and the powerful gravitational field of the Jupiter has led to the formation of several different regions. ‘Mean-motion Resonance’ is one of the most important factors, which contribute to the properties of the Main Belt. It occurs when the orbital periods of two bodies, orbiting around a third, match with each other. Carruba summed up their statistical findings by saying,

Between 33% and 35% of the asteroids in the Main Belt are members of families. There are over 120 recognizable families and dozens of less statistically significant groups. Large families comprise hundreds of members, whereas small families may have some ten members.”  

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