Possible Rapid K-Line Variations in Two High-Galactic-Latitude A Stars

In 1959, Luis Münch ( 1959 ) reported on spectroscopic observations of HD 51106 made with the Tonantzintla Schmidt telescope in 1957, at a dispersion of 241 A/mm at Hy. Between February and March the K line varied in intensity from that found in type A2 to that in type A7. More recently, variations have been observed in the strength of the K line of 73 Draconis by Berg and Wood ( 1966) and by Honeycutt (1966). Honeycutt used the UV spectrograph attached to the 36-inch Cassegrain reflector of the Warner and Swasey Observatory to obtain spectra at a dispersion of 130Â/mm, spaced one hour apart. He found a number of variations in the strength of the K line in these short intervals. On one plate the K line extended only 2/3 of the way across the spectrogram, suggesting that changes of an extremely rapid nature may have taken place. In the course of my research on high-galactic-latitude A stars, spectra of approximately 500 A stars have been obtained in a number of intermediateand high-galactic-latitude zones. The spectra were recorded on Eastman 103a-O plates with the Schmidt telescopes of the Warner and Swasey Observatory and the National Observatory of Mexico at Tonantzintla. Of these stars, two show apparent rapid variations in the intensities of their K lines. In each case, two plates have been obtained of the stars. On one plate the star shows a normal A-type spectrum of about A3-5 on the basis of the strength of the K line. On the other plate, the K line is not continuous across the spectrum; the spectral classification ranges from AO to about A3. Figure 1 shows finding charts for the two stars and gives approximate 1966 positions. North is up, west is to the right. Plate I shows their spectra, reproduced from the original objective-prism plates. All exposures were one hour long. Widening was accomplished by