148 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1925 



proximity to the theoretical curve is very striking, and forms a 

 strong confirmation of the validity of the theoretical work. 



Curiosity, we suppose, led him to wonder where the points would 

 lie representing similar data for the dwarf stars. Now the dwarf 

 stars were so named by Prof. Henry Norris Russell because they 

 are so dense, due to gradual contraction, that it was thought impos- 

 sible that the gas laws could hold true in their case. Hence a rela- 

 tion between mass and luminosity explicitly based upon strict adher- 

 ence to the gas laws would not be expected to hold good for a star 

 of the dwarf type. But, mirabile visu, the plotted points for data 

 taken from dwarf stars conform as well to the theoretical curve 

 as in the case of the giants. 



This was an astounding fact suggesting as it did that the dwarf 

 star, no matter what its density, was in the state of atomic agitation 

 of a perfect gas. The explanation given by Eddington seems plau- 

 sible, though it has not been accepted unanimously — namely, that 

 where matter is subject to such high temperatures as exist in the 

 stars, temperatures to be measured in millions of degrees, each atom 

 is reduced in effective volume a hundred thousand times since its 

 revolving electrons, whose outermost orbits determine its normal 

 effective volume, are all stripped off or ionized b}^ the intensity of 

 heat. Each electron is thus so endowed with energy that it moves 

 about as an independent unit unrestricted to any atomic orbit. Thus 

 a free gaseous state can exist in spite of much closer packing than 

 would suffice at ordinary temperatures to reduce the matter to the 

 state of liquid or solid. 



DENSE STARS 



This conception, if it be true, throws light on a long-standing 

 astronomical mj'stery. There are known to be a few stars, like the 

 lohite diva?'/ companion of Sirius, so small yet so massive that their 

 density worked out to be of the order of fifty thousand times that of 

 water — an absurdity it was thought, an impossible result, something 

 radically wrong somewhere in the observations or calculations. But 

 instead of finding something wrong with the calculations, Edding- 

 ton's work suggests that the trouble lay in our thinking the result 

 absurd, in our failure to realize the tremendous difference between 

 the state of matter at terrestrial temperatures and at stellar tem- 

 peratures. 



GIANTS AND DWARFS 



If, then, all the stars arc in a true gaseous condition, it is necessary 

 to modify all ideas and calculations based on the old point of view 

 that the dwarf stars were not obeying the same laws of pressure. 



