Latest Search for the Elusive Planet Nine Falls Short

Astronomers have purpose to imagine {that a} huge object is ready to be found within the outer reaches of the photo voltaic system—the so-called Planet Nine. A current seek for this proposed planet produced a null end result, however the case is way from closed.

Planet Nine, if it’s out there, is doing a stellar job of staying invisible. A group of researchers led by Sigurd Naess, a researcher on the Institute of Theoretical Astrophysics on the University of Oslo in Norway, was the most recent to aim to identify it, utilizing the Atacama Cosmology Telescope in Chile. “No significant detections [were] found,” they write of their new paper, revealed in The Astrophysical Journal.

That a ninth planet exists in our photo voltaic system is a definite possibility, as scientists Konstantin Batygin and Michael Brown cogently argued in 2016. Astronomers have an inkling to its presence owing to the peculiar actions of objects within the distant Kuiper Belt. To date, over 30 of those objects have been recognized, every exhibiting exaggerated and inclined orbits in addition to clustering conduct.

To clarify this, scientists have invoked the presence of a relatively giant object—the proposed Planet Nine. But for this to work, the planet should be moderately huge and heavy. Astronomers determine that the planet is between 5 and 10 instances the scale of Earth and positioned so far as 200 au to 800 au (18.6 billion to 74.5 billion miles) from the Sun. Large, or no less than large-ish, objects do exist within the area past Neptune—objects like Pluto, Eris, Haumea, and Makemake—so the concept isn’t completely bananas.

It would possibly seem to be we should always’ve noticed one thing so huge a very long time in the past, however our failure to detect the article is just not altogether stunning, given the distances concerned and the probably dim nature of the planet. If it’s on the market, Planet Nine is reflecting little or no daylight and emitting scant quantities of radiation. In earlier surveys, astronomers failed to detect it with the Wide-field Infrared Explorer, resulting in rival theories that try to clarify the Kuiper Belt anomalies, comparable to a bowling-ball-sized black gap within the Oort Cloud or a huge ring of particles within the outer photo voltaic system.

For the most recent search, the group used the Atacama Cosmology Telescope, which scans area at millimeter wavelengths. ACT is primarily used for learning cosmic microwave background radiation produced by the Big Bang, however the telescope’s sensitivity lends itself to this sort of needle-in-a-haystack search. Arthur Kosowsky, an astronomer on the University of Pittsburgh and a co-author of the research, mentioned ACT was up for the duty owing to 2 distinctive traits.

“We have sufficient sensitivity to microwave-wavelength radiation to possibly detect Planet Nine’s thermal emission, and we have observed a wide swath of the sky where Planet Nine might be located,” he defined in an e mail. “ACT is the only current experiment which meets these two criteria.”

The group took observations at 98 GHz, 150 GHz, and 229 GHz as they looked for an object at distances between 300 and a couple of,000 au (1 au is the common distance from Earth to the Sun). For an object 5 instances greater than Earth, the scientists anticipated to see one thing between 325 and 625 au, and for objects 10 instances greater than Earth, they anticipated to see one thing between 425 and 775 au.

The astronomers scanned 87% of the sky accessible from the southern hemisphere, gathering information from 2013 to 2019. Various strategies have been used to course of the info, together with a computational “binning and stacking,” a technique that “might uncover faint sources but at the expense of losing positional information,” in keeping with a press release from the Center for Astrophysics | Harvard & Smithsonian.

No one is aware of the place Planet Nine sits within the sky, if it’s actually there, nevertheless it should reside inside sure ranges to clarify its gravitational affect. At the identical time, the hypothetical planet is shifting, and in particular potential instructions.

“Since we don’t know which position or direction of motion, we performed a computational search over all 100 million possibilities,” mentioned Kosowsky. “For each one of these possibilities, we averaged together all of the data we collected along one specific path to see if we can pick out a faint source moving along that path.”

Naess and his colleagues discovered just a few promising paths, however this got here with a catch. By doing this 100 million instances, “you are bound to find some paths which look like an object is there, but really that is just due to random noise in the data,” Kosowsky defined.

As the astronomers write, their scan produced round 38,000 “raw candidates,” of which roughly 3,500 might be categorized as one thing approximating Planet Nine. Perhaps discouragingly, “none” of those candidate indicators “could be confirmed,” and “there were no statistically significant detections,” the Center for Astrophysics launch mentioned. The group is 95% assured that the brand new survey excludes a photo voltaic system object contained in the surveyed space with the acknowledged search properties.

Still, the group listed the ten strongest candidate indicators for potential follow-ups. But even then, “our 10 brightest average signals looked just like we would expect from random noise,” mentioned Kosowsky.

This newest survey can hardly be described as exhaustive, because the analysis eliminates about 17% of the full potential orbits during which Planet Nine may be shifting if it’s a 5-Earth mass object, and 9% of the potential orbits for a planet with 10 Earth plenty. “There are still a lot of places Planet Nine can be lurking,” Kosowsky added.

With new telescopes poised to return on-line within the close to future, astronomers might lastly have the instruments required to detect one thing so faint and distant. Planet Nine can solely cover for thus lengthy.

“I’m confident that if Planet Nine is out there, astronomers with new telescopes will nab it over the next five years,” mentioned Kosowsky.

More: Is the Elusive ‘Planet Nine’ Actually a Massive Ring of Debris within the Outer Solar System?