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Speckle Observations of Binary Stars with the WIYN Telescope. III. A Partial Survey of A, F, and G Dwarfs
Two hundred thirty nearby main-sequence stars with spectral types in therange of A to G have been observed by way of speckle interferometryusing the WIYN 3.5 m telescope at Kitt Peak, Arizona. The stars had noprevious mention of duplicity in the literature. Of those observed, 14showed clear evidence of a companion, and 63 were classified assuspected nonsingle based on a power spectrum analysis. The remainingstars discussed show no evidence of duplicity to the limit of thedetection system in high-quality observations. The WIYN Observatory is ajoint facility of the University of Wisconsin-Madison, IndianaUniversity, Yale University, and the National Optical AstronomyObservatory.
| Spectroscopic tests of photoelectric stellar classification of abnormal stars
Spectroscopic classification is obtained for 169 northern A5-G0 starspredicted by Olsen (1979, 1980) to have abnormal spectra on the basis ofStromgren four-color photometry. The success in identifying reddenedearly type stars was nearly 100 percent, for Am and early type weaklined stars about 75 percent, for stars above main sequence about 50percent, for composite spectra about 25 percent, and for Ap and LambdaBoo stars 0 percent. Thus photoelectric photometry is a successful firststep in discovering stars of the more extreme spectroscopicabnormalities.
| Estimation of spectral classifications for bright northern stars with interesting Stromgren indices
The purpose of this investigation is to provide spectroscopic observerswith finding lists of potentially interesting objects. From anunpublished UVBY catalogue of 7026 northern stars (mostly brighter than8.3m) 1094 objects with interesting combinations of UVBY indices havebeen selected. Most stars with post-HD classifications have beenexcluded, as well as late F dwarfs belonging to the intermediatepopulation II. For the 792 remaining stars estimated spectralclassifications are given. The techniques and experience from a previouspaper dealing with southern stars have been utilized here. Among thepredicted spectral classifications are 40 OB stars; 262 Ap, Am, or Fmstars; 16 supergiants of types A to G; 110 bright giants of types A to K(class II); 156 double stars or objects with composite spectra; 26 lateF dwarfs; 91 weak-lined dwarf and giant stars of types F to K, includingearly F-type population II field blue stragglers; and a few possiblefield horizontal branch stars, lambda Bootis-type stars, and late-typehalo giants.
| Stars with large proper motions in the astrographic zones+ 32° and + 33° (List I)
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