Searches for Planet 9 Focus on its Many Moons and an Interstellar Object

If you are a bit tired of all of the recent talk about shooting down unidentified flying objects, we’ve got a change of pace for you. Today we’re going to discuss an unidentified flying planet and an unidentified flying asteroid. Specifically, the UFP is Planet 9, everybody’s favorite possibly missing solar system member, and CNEOS14 is an interstellar comet or meteor that splashed into the Pacific Ocean in 2014 and is now the subject of a massive meteor hunt to determine if it indeed long-traveling space rock or a long-traveling space ship. Why are they in the same article? Because one new theory claims astronomers will be able to find Planet 9 by looking for its many moons, while another new hypothesis suggests the interstellar CNEOS14 may have collided with Earth because it was deflected in our direction by Planet 9. Are either or both of these true? Let’s find out.

“However, no optical counterpart has been observed so far to verify the planet 9 scenario.”

In the opening of his new paper published in the preprint journal arXiv, Man Cho Chan, an Associate Professor in the Department of Science and Environmental Studies at The Education University of Hong Kong, expresses the frustration of all seekers of the elusive Planet 9 – no pictures. If our space telescopes can find dwarf planets in the outer reaches of the solar system amongst the Kuiper Belt objects, why can’t they find a large planet? Chan points out that many models show solar system anomalies that could only be caused by another planet, but locating it has been so frustrating that some astronomers are beginning to doubt it is a planet and instead speculate it is a primordial black hole. primordial black hole. Not willing to give up that easily, Chan proposes an alternative scenario.

“Therefore, it is possible that these large TNOs would be captured by P9 to become satellites of P9. Many– 3dwarf planets such as Pluto and TNOs outside Neptune have satellite systems (Brown et al. 2006; Grundy et al. 2019). If these small objects can have satellites, it can be conceived that the more massive P9 might also have a number of satellites.”

Chan starts with the fact that the area beyond Neptune is full of Trans-Neptunian Objects (TNO) and some of the larger ones – like the dwarf planet Pluto – have satellite systems or moons. He speculates that these satellite systems may consist of smaller TNOs captured by the gravity of the dwarf planets and other larger TNOs. Despite being too small to be considered a planet anymore, Pluto has five known moons - Charon, Styx, Nix, Kerberos, and Hydra. If tiny Pluto can have five moons, the gravity of a super-Earth like Planet 9 could have captured many more – Chan says it is those moons which can reveal its location.

"By adopting a benchmark model of Planet Nine, we show that the tidal effect can heat up the satellites significantly, which can give sufficient thermal radio flux for observations, even if Planet Nine is a dark object."

Many astronomers assume one reason we haven’t been able to ‘see’ Planet 9 is that it is a dark, non-reflective object or too far away from the Sun to reflect it, And it definitely has moons - Chan reminds us that all planets in our solar system but Mercury and Venus have at least one moon, and an object with the mass most estimates give to Planet 9 would create enough gravity to capture around 20 trans-Neptunian objects, each with a minimum diameter of 87 miles (140 km). Because these are captured rocks, they are probably jagged instead of round. The drag from those edges plus the sheer gravitational energy needed to hold on to 20 of them tells Chan that Planet 9 is radiating a large amount of thermal radiation – and that heat can be detected by radio telescopes.

“In other words, by obtaining the radio spectrum emitted from the region of the dark P9, if we can detect a relatively strong thermal radio spectrum (Sν ∝ ν2), this would be a solid evidence to verify the P9 hypothesis because there is no other astrophysical mechanism which can increase the temperature of a distant object to more than 50 K.”

So, to paraphrase Fermi’s paradox, why haven’t we found a hotspot in the sky that is Planet 9? Unfortunately, it takes a very long exposure time to gain enough sensitivity to detect the potential thermal signals, so astronomers first need to predict the most likely places Planet 9 might be, then have a telescope or interferometer spend a long time aimed at it. Chan is undoubtedly working on his sales pitch to convince astronomers to try this approach.

Perhaps Chan should talk to Hector Socas-Navarro and Ignacio Trujillo Cabrera, scientific researchers in astrophysics at the Institute of Astrophysics of the Canary Islands. In their new article published in The Conversation, they first look at meteorite CNEOS14 which fell in the Pacific in 2014. Harvard researchers Avi Loeb and Amir Siraj have proposed that CNEO214 was an interstellar object because of the speed with which it entered Earth’s atmosphere, and they are mounting a search for pieces of it to prove this theory. Socas-Navarro and Cabrera looked at the projected path CNEOS14 might have taken and noticed it matched the most common simulations of the path of Planet 9. Simulations of the path of CNEOS214 show that it would not have hit Earth unless something interfered with its trajectory … and that something matched the path of Planet 9. This change in path in astrophysics terms is a “message” or information about a celestial event, and the idea that it was caused by a deflection off of an unknown planet is a “message hypothesis.” In this case, the “message hypothesis” is that CNEOS14 was deflected in our direction by Planet 9 between 30 and 60 years ago.

“If the conjecture is correct, tracing the trajectory of CNEOS14 backwards in time we would find the location of Planet 9 which, according to our calculations , would currently be very close to the point where the constellations Aries, Taurus and Cetus meet.”

The astrophysicists note that they have an “observation campaign” underway at the Javalambre Observatory (Teruel) to scan this trisection of constellations, but the area is still very large. However, it can be done, and their work would fit nicely with Chan’s search for the thermal signature given off by the moons of Planet 9.

Or not.

Socas-Navarro and Cabrera end their article with an appropriate quote attributed to astronomer and Renaissance friar Giordano Bruno:

“Se non è vero è ben trovato (if it is not true, it is well sought).”

In other words, if it is not true, it is still a beautiful coincidence. We probably should spend more time appreciating beauytiful coincidences  instead of getting frustrated by the lack of photos of Planet 9.