382 



KNOWLEDGE. 



October. 1911. 



luminositv produced. One point is obvious, the 

 variable star is sending its vast revolving searchlight 

 through the whole circumference of the heavens. 

 \Mien it is shining away from us it will light up all 

 those dust particles that are on the further side, and 

 illumine them as the Sun does our satellite when it is 

 full moon. Hence we have an obvious explanation 

 of the phenomenon that characterises a number of 

 variable stars, namely, that they present a nebulous 

 appearance at minimum, that is. when the star is 

 sending the searchlight of its \'ast volcano awa\- 

 from us. Such, then, are some of the characteristics 

 of the torn suns, \\ e 

 also see how amazingly 

 impacts must differ the one 

 from the other : collisions 

 must occur between suns 

 of great difference of mass, 

 of differences oi density, 

 of age and hence of 

 luniinositN'. and then again 

 we have collisions from 

 the mere graze of the atmosphere to almost direct 

 impacts. We may have impacts in which the size 

 of the two impacting bodies are so unequal that the 

 one ma\- bur\- itself in the bod\- of the other, and 

 produce a gigantic \'olcano. such as I ha\e imagined 



I ha\e 

 Wnrlds and 



Fig I- RE 11. 



I)iai,Tani showing iiiateiiH 

 the preceding end of valley. 



gigantic \'olcano. sue 

 to have originated the \ariabilit\- of Mira 



grazes, of course much deeper than the mere atmos- 

 [iherc. Nova Persei is an example of a deeper graze 

 although shallow. The Pilgrim star of Tycho 

 Hrahe was a still deeper. Nova Persei appears once 

 to have struck deep enough to have wedded it into a 

 double star. Then we pass through grazes deep 

 enough to produce double stars that are capable of 

 being separated only by powerful telescopes. With 

 still deeper grazes it is dynamically certain that the 

 collision must result in spectroscopic binaries in 

 which the stars revolve around one another in 

 periods of onl\- a few days : of such a type is .\lgol. 



and the Cepheids. The 

 \ana lii lit\' of se\'eral of 

 these a[.)pears to be due 

 almost entirelv to mere 

 eclipse, the great volcanoes 

 that were existing at the 

 time they wedded have died 

 down : but a surprising 

 numlier of these stars, 

 both eclipsing and otherwise, 

 still show the blaze of the \'olcanic scar that was 

 l)roduced by the tremendous blow of their encounter. 

 Again, we go to deeper grazes and the stars scarcelv 

 separate, the \'ast meteoric nucleus of the third star 

 remains as a huge tongue of fire ioininj; the re- 



dragged to 



volvini? stars 



th 



IS 111 



T\u 



I'.irth 



ot 



the minute 

 |)heiioniena 



discussed 

 Systems." 



Some .scientific nun have objected to 

 detail in which I have describ(_>d the 

 deduced as following grazing 

 impacts. They say that we 

 cannot know the exact cir- 

 cumstances, as every con- 

 ceivable variet}' may occur : 

 but grant that we have suns 

 anything like approximately 

 equal, and of the compact- 

 ness that characterises most 

 of them, then there are six- 

 teen well marked characters and basic projierties that 

 the third bodv must exhibit as deduced dynamical 

 generic principles. 



Obvioush- we cannot describe a tithe of all the 

 endless possibilities of variation, but we will just take 

 one kind and imagine pairs of similar suns coming 

 into collisions in which the imi)acts differ from a 

 mere graze of atmospheres down to the almost direct 

 collision, similar to that which in all probability 

 originated our solar system. 



With a very shallow graze we have an evanescent 

 flash of light, and the formation of a pair of variables 

 that will continually increase their distance from one 

 another, due to the original proper motion not having 

 been wholly destroyed by the very slight attraction 

 of the small third body. 



The pairs of variables given on page 89 of '" Birth of 

 Worlds and Systems," are examples of shallow 



Figure 12. Diagram" showing uhy the light in 

 recently torn variables rises (|nicl<ly and falls slowly. 



into one immense dumbbell-shaped 

 mass of fire. The torn suns themselves, although 

 one vast fier\- mass, mav still show signs of the giant 

 volcanoes that are still active on the surface, but 

 tidal action has sto[)i)ed independent rotation, and 



all changes of brillianc\' 

 or of character are s\n- 

 chronous with revolution, 

 because revolution and 

 rotation have become iso- 

 chronous the one with the 

 other. The best example 

 of this is Beta L\rae. 



When the depth of the 

 graze reaches to a cut of 

 more than a third, unless the original proper motitin 

 was enormous, the capturing power of the third bod\- 

 becomes so very great that the three stars do not 

 part company, but w hirl around one another as a huge 

 bun-shaped mass. There is every reason to suppose 

 that some of the Wolf-Rayet stars have originated in 

 this way, and their spectrograms tell us the storv 

 that this is the mode of their genesis. This fusion 

 we call cases of " whirling coalescence." 



Still deeper collisions, and suns revolving slow!'.' 

 are produced. It would seem h\ the low angular 

 velocity of our Sun that this must have been its origin. 

 It has been suggested in m\- various books on the 

 subject, that planets did not originate from the bodv 

 of the sun. but were step-sons and daughters that 

 belonged to tJiie or both of the original bodies whose 

 coalescence made uj) the Sun. 



Professor See has called his ereat book " The 



From "The Riiih cif W'cjild.^ and Sv'stcms." 1>\ kind permission of Messrs. Harper and Hrothers. 



