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The Pamphlet Collection of Sir Robert Stout: Volume 76

Nebulæ

Nebulæ.

60. If stars come into partial impact, the tendency to form nebula; of definite form, other than planetary or cometic, seems to be entirely destroyed by the outrush of the high-velocity gas. This is not the case with the impact of nebulæ.

61. Impact may take place between nebulæ, between star-clusters, between meteoric swarms, and between any two similar or dissimilar celestial bodies. The graze may be little or large; the original bodies may have had a small or great proper motion; and all these peculiarities will tend to vary the results.

62. If two nebulæ come into a slight grazing impact there will result a double nebula, which will show a spindle at the centre. As they are parting company they may have temporarily a dumb-bell appearance; but, as the two sides of page 20 the coalesced nebula are moving in opposite directions, a spiral begins to form at the centre. As the ends travel on in space the spiral would increase, and ultimately a double spiral would result.

63. One or both of the original nebulae may be entangled in the spiral.

64. If the impact be considerable, the two nebulæ do not escape each other, and an annular, nebula results. It would have gauze-like masses of nebulae at the poles of the ring, produced by the outrush of gas during the impact.

65. There are nebulae corresponding to every one of these conditions: nebulae coming into impact—some in impact with the spindle showing between them; there are also spindle nebulæ left alone; others with an incipient spiral visible at the centre; others where the spiral is more distinctly visible; and others where the double spiral is fully developed.

66. Finally there are annular nebula; with the gauze-like caps referred to above. Thus at one and the same time the evolution of nebulæ at any of its stages may be watched, and not unlikely older drawings may show the less advanced stages of the same nebulæ.