The far reaches of the solar system are a strange and mysterious place. Beyond Neptune’s orbit, where it is cold and dark, a swarm of icy objects called the Kuiper Belt orbits the Sun, believed to be more or less unchanged since the birth of the solar system.
Because it is so dark and far away, and the objects are so small, it is difficult for astronomers to discern what exactly is going on there. This makes the results of recent research quite wonderful. Using data from the Dark Energy Survey, astronomers identified 815 Transneptunian (TNO) objects, including 461 newly discovered.
This is a big shock to the nearly 3,000 TNOs known to the Outer Solar System, information that could help us better model the formation of the solar system, and possibly even search for the elusive new planet. .
The new catalog has been submitted for publication and is available on the arXiv preprint server.
“This catalog contains 817 confirmed objects (461 first discovered in this work),” the researchers wrote in their article.
“This is the second largest TNO catalog from a single survey to date, as well as the largest catalog with multiband photometry.”
The Dark Energy Survey did not seek to find TNOs. It operated between August 2013 and January 2019, collecting 575 nights of infrared and near infrared data over the southern sky. The aim was to study a range of objects and phenomena such as supernovae and galaxy clusters in an attempt to calculate the acceleration of the expansion of the Universe, which would be influenced by dark energy.
But the high degree of depth, breadth and precision of the survey proved to be very good for finding objects in the distant solar system as well – beyond Neptune’s orbit to about 30 astronomical units.
Last year, astronomers analyzed this data to find over 100 new minor planets, a category that includes anything that isn’t a comet or a planet, roughly.
The new work, led by the same team and using an improved detection pipeline, adds 461 more. The researchers also ran TNO detection simulations, to compare their results and see if their techniques were accurate.
This region of space is fascinating. With very little to disrupt their orbits, astronomers believe the NWT retains traces of the dynamics of the early solar system. During this time, according to current models, the planets were forming and moving – the system would have been very different from what it looks like today.
As the giant planets maneuvered in their current orbits, their gravitational interactions influenced the orbits of the NWT. These resulting orbits can be studied to reconstruct the events that made them so; because TNO clusters can have quite different orbits, the more we find, the more accurate the reconstruction.
Also, the orbits of a subset of TNO are really weird. These are called extreme TNOs, with an average orbital distance (or semi-major axis) greater than 150 astronomical units. Some astronomers believe the extreme NWT is evidence of something causing gravitational heckling – the hypothetical Planet Nine.
We didn’t find many of these objects, so each new one adds an additional data point that could help find or rule out the existence of Planet Nine. The new catalog adds nine more extreme TNOs to the mix, four of which have semi-major axes greater than 230 AU.
The researchers also found a number of objects with orbital resonances with Neptune, that is, when bodies have orbital periods with a single ratio; four new Neptune Trojans, or asteroids that share the planet’s orbit in gravitationally stable Lagrange points; a large comet called C / 2014 UN271 (Bernardinelli-Bernstein) traveling inward towards the Sun (although it only comes to Saturn before leaving); and a notable “detached” object, so named because its orbit is not influenced by Neptune, with an extraordinarily high orbital angle to the plane of the solar system.
According to the researchers, all of this new information represents a significant increase in our understanding of the outer solar system. So far, Dark Energy Survey data has contributed to about 20% of all known TNOs, which is pretty huge.
“These will be valuable for further detailed statistical testing of training models for the Transneptunian region,” the researchers wrote.
The article has been submitted to the AAS and is available on arXiv.