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A search for rapid oscillations in chemically peculiar A-type stars
In 1995 we initiated a Northern Hemisphere survey for rapidlyoscillating Ap stars. This paper presents the results including one newroAp star (HD 122970), the confirmation of rapid oscillations of HD99563 and apparent null results for other stars. Using Hipparcos data astatistical analysis of the absolute magnitudes and galacticdistributions of all known roAp and noAp stars (also taken from theliterature) was made. A systematic trend for most of the program starsin a M_{ V} vs. beta (index of the Strömgren uvbybeta system)diagram was detected leading to the conclusion that beta issystematically influenced by the chemical peculiarity and/or magneticfield. Three roAp stars are outside the delta Scuti instability stripwhich implies that the driving mechanism of the two classes of pulsatingstar is different. This is also suggested by new pulsation models. Nostatistical difference between the galactic distribution of roAp andnoAp stars was found.
| Photographic measurements of visual binaries
The results of 164 photographic measurements of 50 large and, generally,neglected visual double stars are presented. The measurements have beenmade at Brera-Merate Observatory during the years 1984-88 with Zenastrograph.
| A second list of wide visual binaries
Not Available
| A second list of wide visual binaries
Not Available
| Ages and uvbybeta photometry of wide visual binaries. II
Visual magnitudes and color indices b-y, m1, c1 and beta have beenobtained for the members of 39 double or multiple systems containingstars with magnitudes greater than 4m. Relationships between stellarages, spectral types and photometric indices are given from a sample ofabout 3,500 stars. Data is presented with regard to MK spectral types,the separation, and absolute magnitudes; also tabulated are the meanvalues of photometric unreddened indices with their standard deviationfor intervals of 0.2 in log age. From calculations for each binary ofthe relative difference in the ages of the components and the differencein the effective temperatures, an increase in the relative differencesin ages with the differences in temperatures is noted.
| 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.
| UVBY beta study of A-and F-type visual binaries. I.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976AJ.....81..107M&db_key=AST
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