5« 



Walter Gyllenberg 



Milky Way. In the computations we have however to consider the different relative 

 velocities of the sun table IVb page 20. In this table the value of S is for the 

 stars surrounding the pole of the Milky Way very small — 3.864 Sin. — 



There is, however, no reason to assume the value of S to vary in relation to 

 stars of different galactic latitudes. On the other hand the apex solution from 

 stars surrounding the pole of the Milky Way will give a rather uncertain value of 

 S on account of the position of the apex near the galactic plane. This velocity 

 must however necessarily exceed the lowest velocity observed for the different 

 spectral class stars. I have therefore in the solution used the values 4.000 and 4.ioo. 



The following table gives the results: 



Parallaxes of stars of magn. < 4.9 : 



Surrounding the galactic plane Surrounding the galactic pole 



n it n n 



611 0".oi35 4 1 7 0".oi76 (assuming S = 4.100) 



0".0181 ( » 8 — 4.000) 



The large difference in these parallaxes is very striking. The value n = 0.0181 

 for stars in the polar zone I have assumed as the most probable; it is rather too 

 small than too large. 



Is the difference in the parallaxes caused by the distribution in the two zones 

 of the stars, especially the class B stars, whose parallax is very small? If this is 

 the case we may from the parallax values in table XVIII compute the parallaxes 

 in question. Putting the weights equal to the number of the stars this calcula- 

 tion gives: 



Computed parallaxes of the stars of magn. <4.9: 

 Surrounding the galactic plane Surrounding the galactic pole 



jt = 0".01B4 Tt = 0".0165 



The variation is not sufficient to establish the first results to be exclusively 

 caused by the distribution of stars of different spectral classes in relation to the 

 Milky Way. 



53. Assuming the mean parallax of stars of magn. < 4.9 to be expressed as a 

 function of galactic latitude through the formula 



tr 1 = a 4- b sin ß, 



an integration of this function for the two zones — 30° < ß < + 30° and 

 ± 60° -< ß «< ± 90° will give the numerical value of the coefficients a and b. Thus 

 the variation of & 1 with galactic latitudes is approximative^ given by 



t>! = 0".0134 + 0".00B8 sin ß. 



