Distant Object ‘DeeDee’ Makes the Dwarf Planet Grade

via Tallbloke’s Talkshop
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The 1,100 year orbit of ‘DeeDee’

The solar system’s dwarf-planet population is about to increase by one, reports Space.com. The far-flung object 2014 UZ224 — informally known as DeeDee, for “Distant Dwarf” — is about 395 miles wide (635 kilometers), new observations reveal.

That means the frigid object probably harbors enough mass to be shaped into a sphere by its own gravity, entitling it to “dwarf planet” status, researchers said.

Astronomers first spotted DeeDee in 2014 using the optical Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile (though they didn’t announce the discovery until 2016).

The initial Blanco observations allowed the discovery team to nail down DeeDee’s orbit. The object loops around the sun on a highly elliptical path that takes more than 1,100 Earth years to complete; it’s currently about 92 astronomical units (AU) from the sun but comes as close as 38 AU and gets as far away as 180 AU. (One AU is the average Earth-sun distance — about 93 million miles, or 150 million km.)

DeeDee is therefore the second most distant “trans-Neptunian object” with a confirmed orbit at the moment, researchers said. The dwarf planet Eris is more far-flung, though that’s not always the case; Eris is currently about 96.5 AU from the sun, but it never gets more than 98 AU from Earth’s star.

For perspective, Pluto orbits the sun at an average distance of 40 AU, with a maximum orbital distance of 49 AU.

Continued here.
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Talkshop note: the ratio of DeeDee’s perihelion (closest approach to the Sun) and that of Neptune is around 1.273:1 or the square root of Phi (the golden ratio) to one. For comparison the equivalent Pluto:Neptune ratio fits the 1:1 superresonance (see below).

Re Pluto and Neptune: ‘…the longitudes of ascending nodes of the two bodies—the points where they cross the ecliptic—are in near-resonance with the above libration. When the two longitudes are the same—that is, when one could draw a straight line through both nodes and the Sun—Pluto’s perihelion lies exactly at 90°, and hence it comes closest to the Sun when it is highest above Neptune’s orbit. This is known as the 1:1 superresonance.‘ – Wikipedia