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The Pamphlet Collection of Sir Robert Stout: Volume 76

Stellar Collision

Stellar Collision.

1. The new photographic charts have demonstrated that there are over a hundred million bright stars in the Milky Way.

2. The companion of Sirius and the dark component of Algol prove the existence of dead suns. These are possibly very numerous. Sir Robert Ball thinks them more numerous than luminous page 3 ones: for, other theoretical reasons than his I believe him to be right.

3. Stars have an independent velocity or proper motion of about ten miles a second upon an average. Recent spectroscopic observations seem to suggest a slightly higher velocity than this.

4. This motion is apparently without much order. It will alter the relative distance of stars, and may bring them near each other, and possibly into impact.

5. If they are brought near each other their mutual attraction will alter their velocity, and curve their courses into hyperbolic orbits. If they do not graze they will ultimately again attain their original proper motion.

6. When stars are very near each other their attraction will cause them to be distorted into an egg-shape.

7. The tendency to collision will therefore be increased by their mutual attraction in these two ways, for it will cause them (1) to curve their courses, (2) to be distorted when very near each other. The chances of collision will thereby be made one hundred times greater on an average. In the case of two such bodies as our page 4 sun the chances of collision would be about one thousand times greater.

8. All impacts brought about in this way by deflection will be of a grazing character; consequently nearly all stellar collisions of approximately equal bodies will be of a grazing character.

9. The average velocity of stars at impact will be hundreds of miles a second, and in many cases thousands. The average "proper motion" will not appreciably affect the final velocity. Thus a proper motion of ten miles will add less than half a mile a second to a colliding velocity (velocity acquired by attraction) of one hundred miles a second.

10. A mere graze of the atmospheres of stars obviously will not cause them to coalesce, nor will a slight graze of the stars themselves. As a mean result, when more than a third of each of two equal bodies collide, coalescence will ensue, but this will depend on the original proper motion. Were nine-tenths of 1830 Groombridge to collide with a similar star the remaining tenth would not be stopped in its course; it would pass on in space, the bulk of the two stars temporarily coalescing and then dissipating into space.

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11. The effect of the collision will be to intensely heat the colliding parts. Were the surface of the sun composed of oxygen the temperature produced by a slight graze would be about 120,000,000 centigrade.