Illuminate a way to find planet nine

The search for planet nine – a hypothetical ninth planet in our solar system – could boil down to locating the faintest orbits in an incredibly dark corner of space.

This is exactly what Yale astronomers Malena Rice and Gregory Laughlin are trying to do with a technique that captures scattered light from thousands of space telescope images and identifies orbits for previously unknown objects.

“Without this method, you can’t really see them. When Planet Nine is out there, it will be incredibly dark, ”said Rice, lead author of a new study accepted by the Planetary Science Journal.

Rice, a Ph.D. The National Science Foundation’s astronomy student and Graduate Research Fellow presented the findings on October 27 at the American Astronomical Society’s Department of Planetary Science annual meeting.

The possibility of a ninth planet in Earth’s solar system beyond Neptune’s orbit has gained momentum among astronomers in recent years as they study the strange orbits of a group of small icy objects in the Kuiper belt. Many astronomers believe that the orientation of these objects and their trajectories indicate the influence of an invisible object.

Although the vast majority of the light observed by planets in the solar system is reflected light, for a planet as distant as Planet Nine, the amount of reflected sunlight drops dramatically, probably 12 to 23 times farther from the Sun than Pluto.

If it existed, planet nine would be something called Super Earth. It would have 5 to 10 times the mass of the Earth and would be hundreds of times farther from the Sun than Earth and 14 to 27 times farther from the Sun than Neptune, said Laughlin, lead author of the new study and professor of astronomy at the Faculty. of Arts and Sciences.

This is an almost completely unexplored region of space.

Gregory Laughlin

“This is a region of space that is almost completely unexplored,” Laughlin said.

To detect otherwise undetectable objects, Rice and Laughlin use a method called “move and stack”. They “move” images from a space telescope – like moving a camera while taking pictures – along predefined sets of potential orbits. They then “stack” hundreds of these images in a way that combines their dim light.

From time to time the light shows the path of a moving object such as an asteroid or a planet.

According to Rice, moving and stacking have been used in the past to discover new moons in the solar system. This is the first time it is being used on a large scale to search a large area of ​​space. The images she and Laughlin used came from the Transiting Exoplanet Survey Satellite, a space telescope normally used to find planets outside our solar system.

The researchers tested their method by successfully searching for light signals from three known trans-Neptunian objects (TNOs). Next, they conducted a blind search for two sectors in the outer solar system that could reveal planet nine or previously unknown Kuiper belt objects, and discovered 17 potential objects.

“If any of these candidate objects were real, it would help us understand the dynamics of the outer solar system and the likely properties of planet nine,” Rice said. “This is compelling new information.”

He is currently working with former Yale Songhu Wang postdoc, an Indiana University faculty member, to examine the 17 candidates using ground-based telescopic objects.

Laughlin said the successful use of limited-scale displacement and stacking will pave the way for a broader study of the outer solar system, which is particularly compelling given the possibility of finding a new planet.

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