Asteroids present astronomers and researchers with a lot of amazing opportunities to learn about many different things. Some asteroids have traveled from far outside the galaxy, and others have been orbiting in our own solar system for millions of years.

One of the many interesting things about them is that they can be made up of any number of different things. Some are made of ice, others of rock, and still others of precious metals like gold.

Occasionally, an asteroid will be analyzed that doesn’t appear to be made of anything that we know about, and that is the case with asteroid 33 Polyhymnia. It appears to have a mass that is much greater than could be accounted for if it were composed of rock, gold, or even something very dense like lead.

So, with this puzzle in mind, a team of physicists from the University of Arizona started researching what this type of asteroid, which as a group is known as Compact Ultradense Objects (CUDOs), could be made of.

The team published a study on their findings in the European Physical Journal Plus, and in it they wrote:

“In particular, some observed asteroids surpass this mass density threshold. Especially noteworthy is the asteroid 33 Polyhymnia. Since the mass density of asteroid 33 Polyhymnia is far greater than the maximum mass density of familiar atomic matter, it can be classified as a CUDO with an unknown composition.”

One element that they thought may work was Osmium, which is the densest known stable element, but even that wasn’t dense enough to account for what has been observed with this asteroid. They turned to potential elements with atomic numbers (Z) higher than those found on the periodic table.

Humans have been able to synthesize a variety of superheavy elements, but they are unstable and usually only exist for fractions of a second before breaking down due to their extremely short half-life. Researchers have theorized that elements with even higher density could be stable if they exist in what has been called the island of nuclear stability, which is at and around 164. The team wrote:

“However, elements in the other theoretical island of nuclear stability near Z = 164, which we predict to populate mass density values between 36.0 and 68.4 g/cm³, are reasonable candidates. If some significant part of the asteroid were made of these superheavy metals, it is plausible that the higher mass density could be near the experimentally measured value. Our results on mass density allow us to hypothesize that if superheavy elements are sufficiently stable, they could exist in the cores of dense asteroids like 33 Polyhymnia.”

Exactly what the element may be is still unknown, but this type of research will hopefully generate further interest in these (and other) asteroids.

As asteroid mining technology is developed, it is likely that both space agencies and private companies will be very interested in gathering the first sample of a super-dense element that does not exist on Earth.

If you thought that was interesting, you might like to read about a second giant hole has opened up on the sun’s surface. Here’s what it means.