THE NEW ASTRONOMY. 



II.— DOUr. LR AND WONDER STARS. 



Bv PROFESSOR .\. \V. r>ICKi:RT()X. 



The Star that rules our planetary system is a their cycle, and some only a few hours. They vary 

 comparatively steady and commonplace luniinar)-. in all kinds of different ways, but apparently there 

 The Sun has its storms, but for thousands of )-ears are but few of them Init ma\- be e.xplained on the 



no one knew of them. He is neither strikingly 



large nor inordinantly small. Sir Da\id Gill says: 



■■ Our Earth is a very insignificant [)lanet revoK'ing 



round a very insignificant Sun.'" The more the 



stars are studied, the more complex a ver\" large 



number are found to be, and 



some hundred thousand are 



larger than our Sun. Scores 



of thousands of them are double, 



and between one and two 



thousand of them are known 



as Wonder-stars because the\- 



exhibit fluctuations of intensit\-. 



In 1596, Fabricius missed a 



star that he had seen some 



little time before. Then again 



in a few months he was 



astonished to see. it once more. 



He soon found that there was 



the theorv of 



a rough regularit\- of 



little 



FlGlRE 9. Diagram showing the formation 

 of the orbit of a Double Star. 



'rhe doited circle represents the nebula e.xpanding beyond 



aphelion distance. 

 The two continued hyperbolas represent the path of the 

 two stars had there l)een no collision. The collision occur- 

 ring, the orbit becon.es a long ellipse, thai becomes of 



less eccentricity because the nebula has e.vpanded. 



The meteoric nucleus left behind by the third body will 



produce a resistance at perihelion and this will tend to 



make the orbits more ciicular, as shown in the diagram. 



less than a vear m its waxing 

 and waning period. Because it 

 was in the Constellation of the 

 Whale and such an extra- 

 ordinary star, he called it 

 Mira Ceti, or the wonderful 

 star of the \N'hale. Although 

 we now know over a thousand 

 variable stars, this o Ceti or 

 the star Omicron of the Con- 

 stellation of the Whale, is perhaps still the most 

 remarkable Wonder-star of the entire hea\'ens. and 

 probably man\- astronomers would have to admit 

 that thev know as little of the cause of its re- 

 markable fluctuations as did its discoverer Fabricius. 

 Another verv remarkable variable star is named 

 .Algol, or the Demon star, and this has also been 

 known for a great many years. Mira seems to have 

 every kind of irregularity of variabilitv, whereas retreating stars is subject to the attraction of the 

 Algol is as regular as a clock, and the cause of the other torn sun, and of the new star. That is, each 

 variation of this star is well known. The Demon of the suns when at similar distances are subject to 



an attraction of seven, whereas before the impact 



principle of " partial impact "" aiui 

 the third body." 



Lea\ing actual observation we will return to 

 deduction and trv to trace d}namicall\- what must 

 happen to the two torn suns that we have assumed 

 to have cut deep vallevs in one 

 another, and that have passed 

 oiu- another and are increasing 

 their distance in space whilst 

 leaving between them the e\- 

 l)loding star. One of the first 

 things we must stud\' is the 

 effect of the attraction of this 

 temporary third star upon the 

 two escaping suns. In the story 

 of Nova Persei some few of the 

 salient properties of this third 

 star were discussed. One was 

 that it is thermodvnamicallv un- 

 stable, and hence it necessarilv 

 explodes. Consequentlv it is 

 quite certain that when suns do 

 graze they actualh' must produce 

 a nova. The property we have 

 now to speak of is the power 

 of this bod\' to capture. This 

 property, like its thermod\namic 

 instability, does not seem to 

 be one that is easily grasped 

 b}' observational astronomers. 

 The power of the third star to capture, tends to 

 make the two torn suns into a pair ; that is an 

 orbitally connected double star. Supposing that 

 two equal stars have each grazed off a sixth, the new- 

 third body will have twice the mass lost bv either. 

 Each torn sun will have a mass of five-sixths of 

 v\hat it had before the collision, and the third star 

 two-sixths of one of them. Each of the two 



is a double star, consisting of a dark and a luminous 

 body, and the \'ariation of its light is due to the 

 dark sun coming in front of the bright sun and 

 eclipsing it once in every revolution. Some of these 

 \ariahlu stars take more than a vear to go through 



they were subject to an attraction of six. But the 

 third star remains at rest in space, and the two torn 

 suns are fl}ing from each other, so that the attraction 

 of the third star is eftective longer upon each of the 



37'J 



