Astronomers have discovered 139 new minor planets on the edge of the Milky Way, just beyond Neptune.
The discovery was made by the Dark Energy Survey project, which is attempting to map dark energy in the southern sky. The project uses a 520-megapixel Dark Energy Camera (DES), which is mounted on the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory in Chile.
These minor planets, which are defined as small bodies circling the sun that are neither official planets nor comets, were identified from the first four years of data collected by the project.
Called trans-Neptunian objects (TNOs), they are difficult to spot as they are so small and far away so do not reflect much light.
“The number of TNOs you can find depends on how much of the sky you look at and what’s the faintest thing you can find,” said physicist and astronomer Gary Bernstein of the University of Pennsylvania.
The project originally identified 7 billion “dots” which were reduced to 400 which were analysed to see if they were actually minor planets.
To filter this number, scientists compared the original data set to see if they could find other images of that object.
“Say we found something on six different nights. For TNOs that are there, we actually pointed at them for 25 different nights. That means there’s images where that object should be, but it didn’t make it through the first step of being called a dot,” said graduate student Pedro Bernardinelli who led the research.
To make this work simpler, Bernardinelli developed a way to stack multiple images to create a sharper view, which helped confirm whether a detected object was a real TNO.
After many months of method-development and analysis, the researchers found 316 TNOs, including 245 discoveries made by DES and 139 new objects that were not previously published.
The catalogue of these TNOs will be a useful tool for research about the solar system. By studying the orbits of these objects, researchers might be one step closer to finding Planet Nine, a hypothesized Neptune-sized planet that’s thought to exist beyond Pluto.
“There are lots of ideas about giant planets that used to be in the solar system and aren’t there anymore, or planets that are far away and massive but too faint for us to have noticed yet,” said Bernstein. “Making the catalog is the fun discovery part. Then when you create this resource; you can compare what you did find to what somebody’s theory said you should find.”
Image: Reider Hann/ Fermilab