788 



With 7'^ 10' degrees this gives: 



R^(i = 2,hA0*' hence for (1 = 1 (dissoc. //) /i = 50 (metals) 



R=l,6 v^ 10'' 2,3 X 10'' 



= 28 times liie siiii 3,5 times the sun 

 and will) 7'= JO^ degrees 



/r"/( = 2,5.1 0"'^' hence R— 5 >; 10''^ 7x1"" 



= 71 tiuies (he snn 10 limes the snii 



Considering that at tins high degree of iieat the mass will he 

 highly dissociated, the lirst values are |jrohal)ly nearer the truth 

 than those corresponding to ;< = 50. It siiows that <( Noiut at l/if 

 moment of greatest brighttu'ss is <i hodi/ unick inoir i/i(/((;if/c than the 

 sun, not only in /nininositi/ bnt (tlso in radins anil volume. The 

 theory, that a new star arises when a dark hody of the size of 

 our sun, i.e. an ordinary cooled-down dwarf star, suddenly rises to 

 a colossal temperature, is in conlradicliou with ilie above calcula- 

 tions; for /^ = 7 X JO'", the radius of our suu, with ƒ» =rr 50 and 

 A as observed, the temperature would only lise to 1000°; for 

 7':= 10° A woidd he 10 times larger, (hat is: (he time in which 

 (he star loses its light would he 10 times smallei-. 



This result is in accordance with the value of O'.Ol 1 for the 

 pai'allax of Nova Persei, derived hy Kaptkvn from the supposition 

 that the nebulous i-ings which were phologi-aphed half a year later 

 arose from reflected star-light. This leads to a luminosity 10000 

 times that of the sun ; since the intensity of the surface-radiation 

 was not much different from what it is in an ordinary white istar 

 — Hkktzsprung found a similar distribution of light iii the spectrum 

 of Nova Aquilae as in a A(piilae ') — the radins of the Nova must 

 have been 30 to 50 times the radius of the sun. 



Supi)0sing our interpretation of the dark lines which always ac- 

 company the bright lines on the violet side being correct, this also 

 leads us to a high value of li. The velocity with which the outer- 

 most particles move towards us is R'^J'l.u. At the moment when the 

 light has fallen by two magnitudes, we have ''f/^uit = l, hence 

 R^ifl,n= AR = 2.b X 1<)~'^ /^- I^'or R= the radius of the sun this 

 would become 1.7 km. per second. On the other hand the observed 

 displacement of (he dark lines was as much as would correspond 

 to 700 km. per second. The real velocity must have been smaller, 

 howevei-, since the absorption-line is partly effaced by the broad 

 adjoining emission-line; on the assumption that the velocity may 

 have been about 100 or 200 km. sec. R is fouml e(pial to 60 or 



1) Astonomische Naclirichten Bd. 207. Nr. 4950. 



