According to a new study, the dynamics of unusual things known as “detached objects” may be explained by bumper car-like interactions at the fringes of our solar system rather than a mystery ninth planet.
Collective gravitational torques make eccentric trans-Neptunian objects vulnerable to out-of-plane buckling. This instability causes orbital inclinations to increase, perihelia to rise, and perihelion arguments to cluster.
Ann-Marie Madigan, an assistant professor at CU Boulder, and a group of academics have proposed a new theory for the existence of planetary anomalies like Sedna. This small planet orbits Earth’s sun at a distance of 8 billion miles from the rest of the solar system, but appears to be isolated.
The orbits of Sedna and other detachable objects may have been altered by an as-yet-undiscovered ninth planet beyond Neptune, according to one idea. However, Madigan and her colleagues determined that the orbits of Sedna and its kin may be caused by collisions between these asteroids and space debris in the outer solar system.
“There are so many of these bodies out there. What does their collective gravity do?” said Madigan of the Department of Astrophysical and Planetary Sciences (APS) and JILA. “We can solve a lot of these problems by just taking into account that question.”
The researchers will present their findings at a press conference on June 4 at the 232nd meeting of the American Astronomical Society, which will take place in Denver from June 3 to 7.
Detached objects are a dynamical type of minor planets in the Solar System’s far reaches that belong to the trans-Neptunian object (TNOs) family. In the scientific literature, these objects have been referred to as extended scattered disc objects (E-SDO), distant detached objects (DDO), or scattered–extended, according to the Deep Ecliptic Survey’s formal categorization.
There are so many of these bodies out there. What does their collective gravity do? We can solve a lot of these problems by just taking into account that question.
Ann-Marie Madigan
Detached objects like Sedna receive their names from the fact that they orbit the Sun in gigantic, circular orbits that take them nowhere near Jupiter or Neptune. It’s still a mystery how they arrived to the outer solar system on their own.
Madigan’s team came up with one feasible solution using computer simulations. These frozen particles orbit the sun like the hands of a clock, according to Jacob Fleisig, undergraduate studying astrophysics at CU Boulder. Smaller things like asteroids, on the other hand, move quicker than larger ones like Sedna.
“You see a pileup of the orbits of smaller objects to one side of the sun,” said Fleisig, who is the lead author of the new research. “These orbits crash into the bigger body, and what happens is those interactions will change its orbit from an oval shape to a more circular shape.”
The perihelia of detached objects is substantially greater than Neptune’s aphelion. Their orbits are frequently very eccentric and very vast, with semi-major axes of a few hundred astronomical units (AU, the radius of Earth’s orbit).
In other words, it is solely due to those small-scale interactions that Sedna’s orbit changes from normal to disconnected. The findings are also consistent with studies from 2012, which found that the larger a detachable object develops, the further away its orbit from the sun becomes. The new study was also co-authored by Alexander Zderic, a graduate student in APS at CU Boulder.
The discoveries could also provide light on another occurrence: the extinction of dinosaurs. The orbits of these objects tighten and widen in a recurrent cycle as space debris interacts in the outer solar system. On a predictable period, this cycle could end up launching comets toward the inner solar system, even in the direction of Earth.
“While we’re not able to say that this pattern killed the dinosaurs,” Fleisig said, “it’s tantalizing.”
