When we think of dwarf planets, the first thing that comes to mind is obviously the injustice of Pluto getting demoted to one. But the truth is, these little guys — and there are six currently recognised within our solar system — deserve just as much love as their mightier planetary cousins. Good news for them: a new study suggests that the dwarf planet club could get another member, in the form of a very small, distant object located roughly 92 astronomical units (AU) from the Sun.
Planetary body 2014 UZ224, also known as DeeDee (short for "distant dwarf"), has been getting a lot of attention from a team of scientists who've observed it using the Atacama Large Millimetre/submillimeter Array (ALMA) in Chile. Though DeeDee was first discovered using the Blanco telescope in 2014, this new study has been able to record its size for the first time. By picking up DeeDee's heat signature, the ALMA data suggests the object is about 635 kilometers across, about two-thirds the diameter of dwarf planet Ceres.
If DeeDee has enough mass to be spherical, it would meet the criteria for the International Astronomical Union (IAU) to recognise it as a dwarf planet. In order to be recognised as such, an object must orbit the Sun but cannot be a satellite (like a moon), must have enough mass to be spherical, and has not cleared its planetary neighbourhood of debris. The team's observations were published on April 12th in The Astrophysical Journal Letters.
Image: ALMA (ESO/NAOJ/NRAO)
"This object is currently the second-most distant known trans-Neptunian object with reported orbital elements, surpassed in distance only by the dwarf planet Eris," the researchers wrote. Trans-Neptunian objects (TNOs) are minor objects that orbit the Sun at a distance greater than Neptune does at 30 AU. We suspect there are thousands of TNOs in our solar system, and while they may seem distant and unimportant, they're essentially scraps from the formation of the solar system — so very old and very cold.
Indeed, DeeDee might not be as cute as its name suggests. In addition to taking 1,100 years to complete its orbit around the sun, the object is blisteringly chilly, which makes sense seeing as it's located in the Kuiper Belt where our sun is no more than a bright pinprick in the sky. The region is chock full of ancient ice balls.
"We calculated that this object would be incredibly cold, only about 30 degrees Kelvin, just a little above absolute zero," lead author David Gerdes, a scientist with the University of Michigan, said in a statement.
Despite its unbearable coldness, it'd be nice for Pluto to have another dwarf planet to befriend. We'll be rooting for you, DeeDee.