M
mikeemmert
Guest
The new "planet", 2003 UB 313 or "Xena" (if that name is accepted) I believe initially formed in the Sun/Neptune L4 or L5 point as a binary, with the other object being Neptune's moon, Triton. I also think Pluto and Charon formed in the other stable Sun/Neptune Lagrange point (L5 or L4). These objects escaped because the system was a six-body system, rather than a three-body system. More than three bodies are unstable, eventually.<br /><br />For Triton to have been captured by Neptune, it would have to slow down. If Triton had formed anywhere else but the Sun/Neptune Lagrange point, it would approach Neptune at a considerably greater velocity than Neptune's escape velocity.<br /><br />But it would approach Neptune from a Lagrange point right at escape velocity. Even so, to lose enough velocity relative to Neptune to be captured would involve as much energy as Triton's mass in high explosives.<br /><br />There has to be a transfer of momentum for capture happen. I think the momentum of Triton was transferred to it's former moon, 2003 UB 313.<br /><br />The new objects orbital parameters support that. I'ts perihelion is close to the same altitude above the Sun as Neptune. It's orbital period is in a 20:3 resonance with Neptune.<br /><br />Today, 2003 UB 313 is larger than Triton. However, when Voyager II flew by Triton, geysers were noted. I believe Triton has lost mass in the intervening ages and long ago, Triton and 2003 UB 313 were about the same mass.<br /><br />Triton could have and indeed probably did transfer momentum to original moons of Neptune. However, these were probably not large enough to lower Triton to it's present altitude above Neptune. That would take a large object such as 2003 UB 313. <br /><br />Incidentally, I like the name, "Xena", which rumor says has been proposed for the new object. That would make 2003 UB 313 into Planet X (Roman numeral #10). It's ultimately Mike Brown's call.<br /><br />I don't really think it's a planet, though. It is a K