ASTKUNUMY. 143 



STELLAR SPECTRA. 



Fhotofjraphlc studij of stellar spectra. Jloiri/ Draper memorial. — Pro- 

 fessor IMckeriDg-, in his iuiiuial report for 188S, presents the progress 

 made in the various investigations of stelhir spectra as follows : A cata- 

 logue has been prepared of the spectra of 10,875 stars, covering the 

 entire sky north of — 25o. The Sinch Bache telescope has been used 

 for this work. Six hundred and thirty-three plates have been taken, 

 and 27,953 si)ectra have been examined. The type of spectrum is 

 given in each case, and in aJbontsix thousand cases additional lines are 

 visible and have accordingly been described. The photographic in- 

 tensities of the spectra have also been measured, giving a photometric 

 measure of the stars by which those of different colors may be com- 

 l)ared. The first draft of a spectroscopic catalogue has been prepared, 

 including the place of each star for 1900, its designation and magni- 

 tude in various catalogues, its photographic brightness, and the descrip- 

 tion of each S[)ectrum. The photographs required for the second inves- 

 tigation on the spectra of the lainter stars are nearly completed. The 

 instruments employed in both of these investigations were prepared 

 for shii)ment to Peru, where the work will be continued among the 

 southern constellations. The detailed study of the brighter stars with 

 tlie 11-inch Draper telescope has been extended by the use of plates 

 stained with erythrosin. The sodium liiu». I) in these spectra has thus 

 been photographed as a double line. A catalogue has'been formed of 

 the lines in some of the brighter stars. In Sirius the lines, except 

 those due to hydrogen, are very faint. But nearly four hundred of 

 them have been measured in diiferent photographs of this star; lifteen 

 are recorded between the lines H and K. A beginning has also been 

 made of the study of the spectra of the variable stars. 



Dr. von Konkoly and his assistant, Dr. Kovesligethy, have carried 

 the spectroscopic survey of the heavens begun by Vogel and Duner to 

 15 degrees south declination, and have published their work in volume 

 8, i)art 2, of the O'Cxyalla observations. The instrument used was a 

 Zollner spectroscope. Vogel's arrangement of types was followed. 

 The catalogue contains in all 2,022 stars, down to 7.5 nmgnitude. But 

 one bright line spectrum was suspe(;ted, a star of G.5 magnitude 50' 

 north of C Orionis, and this star, as well as /i, 6, and s Orionis, is found 

 to have a variable spectrum. 



Among the peculiarities detected in stellar spectra maybe noted the 

 discovery by Espin on August 13, 1888, of a bright line in the si)ectrum 

 of the variable star K Cygni; and as Dun6r found it in 1879-'82 of a weak 

 III type, an extraordinary change seems to have taken place. Espin's 

 bright line was apj^arently of a temi)orary character, and faded rapidly. 



Motion of stars in the line of sight. — The spectroscopic; observations tor 

 the determimition of the motions of stars in the line of sight have been 

 continued at Greenwi(;h and at the Temple Observatory, Rugby, the 



