Telescope Reviews: Re: Planetary accretion

I had not thought through the extent of ejected bodies (jetsom?) during planetary system formation. Shostak argued that the "bullets" Jupiter supposedly protects us from were of its own making. That Jupiter basically threw a lot of matter out into the Kuiper/Oort matter reservoirs during the formation of the solar system. Icy KBO "seeds" beyond the snow line would probably be as effective as any for starting Neptune like planets.

Making the case for remnant pieces of iron after a supernova has been the most speculative part of this idea. I know researchers are trying to figure out velocities and elemental compositions of the expanding layers of supernova matter from spectra. It would be interesting to find out if interior layers of the expanding cloud have significantly lower velocities than outer layers. This along with shocks in the inner cloud might keep the iron particles in closer proximity afterwards and lead to fairly 'rapid' re-association of the particles as they cool. Iron would make a very stable seed with a large mass to surface area ratio, and less likely to dissipate from radiation - which drives the fixation on iron.

Excellent point on orbital planes. It would be a great test. One paper I read did a rough calculation on how many passes through an accretion disk it would take to change the orbital plane of a planetesimal skewed to the disk (density/velocity dependent). I'm going to start watching for mention of protoplanetary disk shapes and planarity. There should be a signature visible for a period of time if a seed were to randomly fall into a disk. I believe there is a fair amount of observational data on this already. And yes, this is just one hypothetical way planets *might* start. The idea that planets must always start from pure dust and gas just kept nagging at me as too simple.

an example of the benefits from collaborating on an idea ... thanks!

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Tom C
C10 NGT

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