Is the Sun a binary?

[nemisis] " ... how do planets migrate so far out after fission?"

It's an interesting question, isn't it?

They don't have to. As the nebula contracts into a proto star, and then as that proto star contracts into a star, there are many episodes of over spin. Each pair of planets is shed more or less where it will end up, although some migration does happen due to tidal forces after separation. Those tidal forces are larger when the proto star is larger, so migration for the outer planets is (was, actually) larger than for the inner planets.

LB

Larry, so are the "hot Jupiters" then newly fissioned in your opinion? Will they migrate farther from their star? Or did these stars fission small planets before large ones?

I don't think we are talking about proto stars in these cases, so newly fisioned seems to be ruled out.

Tom has speculated that we do not yet have enough data to tell if what we "see" is the result of one large close planet or two smaller more remote planets.

LB

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by nemesis</i>
<br />The study of extrasolar planets, while there is a strong selection effect, shows a predominance of "hot Jupiters", gas giants orbiting their star in very tight orbits, often having periods of only a few days.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">That is more than a selection effect. In the initial searches, that is the only kind of extrasolar planet that it was possible to discover. And it remains the predominant type of discovery possible in short searches lasting just a few years. There may be innumerable systems with close terrestrial planets or distant gas giants, but most surveys can't see those yet because they require longer and more accurate surveys.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">It has been proposed that this is due to gas and dust in planetary nebulas, resulting in drag and a "death spiral" for newly formed planets.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Yes, you are correct in describing the best ad hoc theory the mainstream has to explain these hot Jupiters. However, those of us who know a little dynamics know how much of a stretch this idea is. "Death spirals" pick up speed as they move inward. Therefore, close to the parent star is the least likely place to find them because they can last relatively little time at close distances. This is similar to the death march of artificial satellites, which may last centuries or longer before starting their death spiral. But each distance increment takes less and less time than the previous one in an exponential pattern. So the end comes quickly.

However, the whole idea of a "death spiral" is itself virtually impossible because it requires drag from a source outside the star system. A local nebula that is part of the system cannot provide drag because the nebula must have the same orbital angular momentum (speed) as the planet or it would fall into or closer to the star immediately. And if the gas and dust are orbiting, then nearby gas and dust are forced to librate, making collisions with the planet impossible. And if the gas and dust are more distant and in elliptical orbits crossing the planet's orbit, then collisions that speed up the planet are just as common as collisions that slow it down, so a death spiral is still impossible. -|Tom|-

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Larry Burford</i>
<br />Tom has speculated that we do not yet have enough data to tell if what we "see" is the result of one large close planet or two smaller more remote planets.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">A minor correction here -- I argued that the data in hand for most extrasolar planets doesn't allow us to tell the difference between one planet in an elliptical orbit vs. two planets in 2-to-1 synchronous circular orbits. Either way, it will look like the parent star accelerates more at some times than at other times. For one planet, this is because the planet is sometimes closer and moving faster in its elliptical orbit, and sometimes farther away from its star and moving slower. For two planets, they are sometime pulling in the same direction, and sometimes in opposite directions. The observable effect on the parent star is the same either way.

So my argument dealt with eccentricity, not closeness. -|Tom|-

"A supernova that close would have wiped out the solar nebula from which the planets formed, and would have made the Sun into a
"peculiar" star (in the stellar classification sense of "peculiar")." - TVF
It seems, since you favor the fission model, this would have no relevance. It should not affect fission.
I believe you said elsewhere that a nearby supernova would have "wiped out" the solar system planets, if any yet existed. But according to the exploded planet hypothesis, a number of solar system bodies, including Mars, are former moons of exploded planets. They were not "wiped out" despite close proximity to an explosion powerful enough to turn more than 98% of a planet's mass into gas and dust. Also, I remember reading that at least one pulsar is thought to have at least two planets. Evidently they survived the supernova of their primary at very close range - at most a few AU, whereas any hypothetical solar companion supernova would have been at hundreds or thousands of AU.