Formation of Star-Clusters and Meteoric Swarms.

31. The hydrogen will rob the heavy molecules of their energy: hence in any considerable graze the heavy metals might not indefinitely expand. They would lose their velocity by radiation and by doing work against gravitation, and they would be attracted back again, and may form a star in the centre of the nebula. Some nebulae have such stars.

32. In a partial impact the coalesced part will not have all its motion converted into heat. The momentum on the two sides will not be exactly balanced. The body will consequently tend to spin. It is generic of partial impact that it tends to cause rotation in all the bodies page 12 produced, and also that the rotation is all In the same direction.

33. It is a peculiarity of oxygen that it tends to render its compounds with metals less volatile than are the metals themselves. Almost all metallic oxides are less volatile than the metals forming them. Consequently, when metallic atoms and oxygen come together, they produce molecules that tend to coalesce. Thus nuclei form in a nebula and it becomes dusty. If the nebula be rotating this dust tends to move in orbits, and it would be constantly picking up other dust and molecules. Thus a rotating metallic nebula, in which molecular selective escape has dissipated the light molecules, tends to aggregate, not necessarily into a single body, but oftener into a number of bodies orbitally connected. If the mass be large it will become a star-cluster, if small a meteoric swarm.

34. In star-clusters, impacts should be frequent. These groups should be photographically observed to notice any sudden increase of intensity. Then the pair of impacting stars should be watched for nebula; and for variability.

35. Star-clusters would as a rule be very deficient in hellium and neon, and also have but page 13 little uncombined hydrogen and not a large quantity of hydrogen in any condition, otherwise it would, except under special circumstances, have become a single star. But partial impact would make gas of the heavier elements and dissipate such gas. This would produce resistance and cause other impacts; thus variable stars may characterize some star-clusters, or special parts of a star-cluster, as is the case.