view Abstract Citations (2) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Finding List of Early-Type Stars in Regions of Intermediate Galactic Latitude Upgren, A. R. ; Staron, R. T. Abstract A list is given of all stars of spectral class F2 and earlier, brighter than magnitude 11.5, found in four regions of intermediate galactic latitude. This objective-prism survey is part of a study of stellar densities aiming at the determination of the inclination to the galactic plane of surfaces of equal stellar density. The distribution of early stars fainter than ii 5, as well as other stars of later type, will be covered else- where. The conclusion is made that the stars included here do not appear to refute the model found by Oort but that the area covered is insufficient for a detailed analysis, as is also the case for other similar surveys cited. I. INTRODUCTION Stars and matter in general can be thought of as lying in layers roughly parallel to the plane of the Galaxy and decreasing in density with increasing distance away from it. The region lying above the Sun and within a few hundred parsecs of the plane is influenced mainly by the comparatively dense matter in the plane. As larger distances are con- sidered, stars fall increasingly under the influence of the massive but distant galactic center. An inclination of surfaces of equal stellar density should be observed, which in- creases as regions well into the galactic halo are considered. Confirmation of these large-scale features in the nearby regions above the plane was made by Oort (1938) in an extensive investigation of stellar densities in the region of the north galactic pole. Oort based his study on star counts in the Selected Areas and on the intervening interstellar absorption. He found large-scale deviations in stellar density suggestive of local spiral structure within 500-700 pc of the plane; beyond, to a distance of 1800 pc, the equidensity surfaces could be best represented by layers inclined to the plane by an angle of 100. More recently Schmidt (1956) has studied the density of neutral hydrogen as revealed by observations of the 21-cm line. He finds an inclination for the interstellar hydrogen similar to the 100 tilt which Oort discovered for the high-latitude stars. The purpose of the investigation of which this paper is a part is to redetermine stellar densities in regions of intermediate galactic latitude lying above the galactic center and anticenter. Such a study is warranted by the great advantage over earlier methods of- fered by Schmidt telescopes, which have a wide, distortion-free field. The combination of these instruments with objective prisms is ideal for large-scale surveys and permits the two-dimensional classification of many stars to be made quickly and directly. The densi- ties obtained, combined with similar data for the region of the north galactic pole, will yield information on the inclination of equidensity layers for each type of star studied. Emphasis must be placed on the main-sequence A-type stars and the late-type giants since they are the only abundant luminous stars observable at large distances from the plane and since their spectral types can be uniquely determined at low dispersion. This paper includes a finding list of the brighter A stars in the mid-latitude regions covered, and a discussion of the results. Further papers will include similar results for other types of stars and for the fainter early-type stars. * Present address: Department of Astronomy and Space Science, State University of New York, Albany, N.Y Publication: The Astrophysical Journal Pub Date: July 1969 DOI: 10.1086/150070 Bibcode: 1969ApJ...157..327U full text sources ADS | data products SIMBAD (432)