In paper A it was put forward that the lesser planets (excluding Mars) came into being towards the end of internal breakup of a protoJupiter, with the remainder of protoJupiter, after ejection of the planets, forming Jupiter. Paper C suggested that the satellites (including Mars) formed in a similar manner to the lesser planets but immediately before them. And in paper B the possible origin of protoJupiter and Saturn was given. In each paper some pertinent evidence was given to support the sequence of events.

It is important to note the order of the subjects given above: paper A, paper C, and finally paper B. The sequence follows stratigraphic geology principles, i.e. a step by step backwards in time approach. This means that the matter in paper A - and because of its similarity, in paper C - had a high probability of having occurred; and even the few pieces of evidence given in the paper make the development almost a certainty. But in stepping back from certainty (the present) and near certainty (origin of the lesser planets and satellites) an increasing element of uncertainty is added, so that the origin of Saturn and protoJupiter, while supported by measured data, must be considered no more than probable. Before this event, with the brown body and the Sun forming the Solar System, there must be even more uncertainty so that what follows must be considered possible, with alternatives arguable.

There is a similarity in development of Saturn and protoJupiter and of the terrestrial planets and lesser gaseous planets, which suggest that the two-body system Sun and brown body came from a common source. No! the brown body did not come from the Sun; it was a sister to it. I suggest the following development after having made a brief literature search.

A slowly rotating molecular cloud began to collapse (inside out?). Material began spiralling in wards (NO radial collapse) and matter obeyed Newton’s laws. That is, heavier matter, whether due to size, density or both, moved more rapidly inwards than the lighter gaseous matter to slowly build an incompletely density-stratified protoSun. Chiefly silicates and irons concentrated towards the centre and the lighter elements, particularly hydrogen and helium, concentrated towards the outer surface. A certain amount of isotope separation also took place during this phase. Because of irregular collapse the protoSun developed an ellipsoidal shape, similar to that seen in planetary nebulae and including the dense centre concentrating at or near one of the focal points of the body. The protoSun, increasing in size and rotation, gradually reached a stage of rotation where matter at the pericentral axis attained escape velocity.

Immediately prior to that point in time being reached there would have been an increasing amount of inward falling matter, particularly gases, approaching the pericentral end of the ellipsoid which would have been slowed down and then repelled outwards. The T-Tauri effect?) This would have increasingly inhibited matter accumulation, driven out lighter matter, and ultimately repelled the collapsing cloud. One consequence of this would be a depletion of the ¹⁶O isotope (and other isotopes), something which is almost unique to our Solar System in our galaxy.

The protoSun up to this stage acted as a single body and, because of its generally very large, light density size but small dense core, had a very small moment of inertia factor. But when matter at the pericentral axis reached escape velocity and moved away from the protoSun surface the instability created resulted in the core material - the incompletely separated silicates, heavy gases, and immediately surrounding lighter gases - moving outwards along the pericentral axis. Immediately such happened the equilibrium of the system became disrupted. No longer was the protoSun a single body system; it became a two body system, in which both bodies had moment of inertia factors approaching 0.4. The effect of this on the hugely dominant gaseous part of the protoSun was for its rotation to rapidly slow, causing collapse of the cloud to form the Sun. Another result of the decrease of rotation of the gaseous body is that the Sun’s angular momentum is small, whereas the protoSun angular momentum was large. However, because the system was a closed one the total angular momentum of the Sun and brown body remained the same as that of the protoSun. This means that most of the angular momentum was transferred to the brown body. Further, there was a large excess of energy developed by the decrease in the gas cloud rotation and part of this was expended in ejecting the core from the collapsing protoSun. The ejected core - to give its later name, the brown body - moved outwards to 5.3 AU. The body’s shape would have reflected that of the protoSun and so was ellipsoidal, if only slightly.

It would make this paper too long to give the data which supports the above development but data there is. That collated by me has been presented in Lee (1994), pp.112-127 followed be a note of a variant to explain some binary stars.