Sol Has A Binary Partner? Options

[ngunn]

[quote name='Myran' date='Apr 27 2006, 05:34 PM' post='52043']
No I mean that Sedna have been closer to the sun earlier.

Whatever event left Sedna in its current orbit must have happened somewhere along that current orbit. That could either be its formation or a perturbation - in either case at least 76AU out.

[Guest_Myran_*]

ngunn wrote: Whatever event left Sedna in its current orbit must have happened somewhere along that current orbit. That could either be its formation or a perturbation - in either case at least 76AU out.

If theres anything I feel more confident about, then it is that Sedna havnt formed on the orbit if has today.

Today it would be quite odd for one natural object to get into the orbit Sedna have, but theres many things that were different in the early solar system. Then there was a strong solar wind, especially in during the T-tari phase I mentioned. Some astronomers have speculated that there was a magnetic field in the planetary nebula, it should also have contained some gas, then we have a large number of planetesimals with their gravitational force. All could have contributed with drag, fields and gravitation to apply a breaking force on Sedna that else would have become a runaway from the solar system.

So I do in fact agree with you that something did contribute to give Sedna the orbit we see, but I dont want to get into speculation on which force cause it or was the main contributor - I simply dont know.

Finally, the orbit of Sedna are unusual, but not completely unique, asteroid Pallas are one other oddball which have a highly inclined orbit. But a majority of the larger asteroids do have orbits in the ecliptic and only moderately eccentric ones. This are likely caused by the planets and the gravitational pushing and pulling which have put the asteroids in more well behaved orbits.
So to me the odd orbit of Sedna are rather one strong indication that there are no larger objects in that remote part of the solar system.