Researchers suggest the pair may have got too close to the hypothetical Planet Nine, resulting in their current orbits.
The dynamical properties of these asteroids, observed spectroscopically for the first time using the Gran Telescopio CANARIAS, suggest a possible common origin and give a clue to the existence of a planet beyond Pluto, the so-called ‘Planet Nine’, reports Phys.org.
In the year 2000 the first of a new class of distant solar system objects was discovered, orbiting the Sun at a distance greater than that of Neptune: the “extreme trans Neptunian objects” (ETNOs). Their orbits are very far from the Sun compared with that of the Earth.
We orbit the Sun at a mean distance of one astronomical unit (1 AU which is 150 million kilometres) but the ETNOs orbit at more than 150 AU. To give an idea of how far away they are, Pluto’s orbit is at around 40 AU and its closest approach to the Sun (perihelion) is at 30 AU. This discovery marked a turning point in Solar System studies, and up to now, a total of 21 ETNOs have been identified.
Recently, a number of studies have suggested that the dynamical parameters of the ETNOs could be better explained if there were one or more planets with masses several times that of the Earth orbiting the Sun at distances of hundreds of AU.
In particular, in 2016 the researchers Brown and Batygin used the orbits of seven ETNOs to predict the existence of a “superearth” orbiting the sun at some 700 AU. This range of masses is termed sub Neptunian. This idea is referred to as the Planet Nine Hypothesis and is one of the current subjects of interest in planetary science.
However, because the objects are so far away the light we receive from them is very weak and until now the only one of the 21 trans Neptunian objects observed spectroscopically was Sedna.
Now, a team of researchers led by the Instituto de Astrofísica de Canarias (IAC) in collaboration with the Complutense University of Madrid has taken a step towards the physical characterization of these bodies, and to confirm or refute the hypothesis of Planet Nine by studying them.
The scientists have made the first spectroscopic observations of 2004 VN112 and 2013 RF98, both of them particularly interesting dynamically because their orbits are almost identical and the poles of the orbits are separated by a very small angle. This suggests a common origin, and their present-day orbits could be the result of a past interaction with the hypothetical Planet Nine.
This study, recently published in Monthly Notices of the Royal Astronomical Society, suggests that this pair of ETNOs was a binary asteroid which separated after an encounter with a planet beyond the orbit of Pluto.
The report continues here.