Could there be a planet that is naturally comprised of elements past ununoctium?

Because elements are classified by the number of protons they have, could there potentially be planets or environments that are so dense that they are made up of elements potentially greater than Ununoctium? Although, it would most likely be ridiculously unstable, the properties of all these new elements and their effects leaves me in curiosity.

• I very much doubt that is possible. Even if it is somehow possible for such a planet to form, I don't see how it could last for any appreciable period of time. – a CVn Apr 22 '16 at 14:25
• Does a black hole count? If not, what about a neutron star? – Xandar The Zenon Apr 22 '16 at 22:05

Sort of.

Planets, in the terrestrial ball of rock sense, won't be comprised of elements past ununoctium, because those elements aren't formed in supernovas, which are what create the majority of the terrestrial elements that form rocky planets. Furthermore, planets don't have enough gravity to hold together larger balls of nucleons through gravity alone.

However, there are objects that do. They're called neutron stars. In neutron stars, intense gravitational forces can stabilize nuclei of substantially greater size than what are found in 'ordinary' matter. Furthermore, the core of a neutron star is of such density that it can, in some ways, be thought of as a single giant nucleus. Unfortunately, most of the heavy nuclei found in neutron stars are expected to have far more neutrons than protons, so it's hard to say exactly what the largest atoms found in a neutron star are in terms of atomic number. Nonetheless, neutron stars are probably the closest thing to a ball made of huge atoms you can find in the universe.

"But wait!" you say, "Those are stars, not planets!" Well, as luck would have it, the new IAU definition of a planet doesn't specify any limits on the composition of a planet, merely on its size. Theoretically, there's no reason a neutron star can't be small, though the circumstances which create them tend to lead to stars with masses a few times that of our sun. If a neutron star were to somehow lose most of its mass during formation and pop out with a mass lower than around 13 Jupiters, and was then captured in orbit around a star, whereupon it would presumably clear its orbit, you would have a planet comprised mostly of huge atoms.

Sort of.

• I expect there are no atoms in neutron stars, not neutron stars with masses less than 1.4 Suns, because the Chandrasekhar limit and neuron degeneracy pressure... – Serban Tanasa Apr 22 '16 at 16:11
• @SerbanTanasa Past the outermost 'atmosphere' of the star, where atoms and molecuels can exist in a stable state, there aren't atoms, per se, since electrons can't stably orbit the nuclei, but there are atomic nuclei. This paper goes into detail about what some of them are: int.washington.edu/PROGRAMS/Baldo.pdf – ckersch Apr 22 '16 at 17:20

Most of the elements theorized to exist at those high numbers are extremely unstable and tend to break down quickly. According to Wiki, all elements over 101 (except dubnium-268) have a half-life less than a day. So unless we discover the 'Island of Stability' (and it is significantly more stable than expected) theorized most of the elements would deteriorate before a planet could even be formed.

It would however suggest that the planet was created by an intelligence should one exist, though why?

• Even the elements of the Island of Stability, if it exists, are unlikely to be that stable. They, too, would most likely decay before a planet could form, though no one can really say for sure. – Aurast Apr 22 '16 at 14:38
• @Aurast I suspected as much – bowlturner Apr 22 '16 at 14:39
• 1-2 isotopes in the island of stability could have half-lives up to $10^9$ years but since we've never found one of those isotopes I think everyone would be surprised if they did have a half-life that large. – Jim2B Apr 22 '16 at 17:46

I'm no nuclear physicist, but I'll take a crack at this. As you stated ununoctonium and the like are extremely unstable. If a planet of ununoctonium appeared it would decay in milliseconds. The only way I could see this happening is if your planet was constantly bombarded with enough energy to continually form new heavy elements. Cosmic ray spallation is known to produce heavier radioactive isotopes (cosmogenic radioisotopes), compared to normal stellar nucleosynthesis. A casual search brought up the idea of a planet bombarded by a ultra-high-energy cosmic ray. A source of these rays, called a Zevatron (I love science words), could be a relativistic jet from an active galactic nucleus. One example of such a jet is in the M87 galaxy, the energy of which has been estimated at 5.1 × 1049J

So basically, a planet directly over the center of a supermassive black hole in a center of the galaxy might be bombarded with enough energy to produce some heavier elements. Or far more likely just disintegrate.