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The association surrounding NGC 2439
The structure of the field surrounding the Galactic cluster NGC 2439 isstudied utilizing uvbybeta photometry of bright OB stars. We collate allphotometric and kinematic data available to identify possible groupings.The stars of our sample show a large scatter in their distances, radialvelocities, proper motions and reddenings. We conclude that they do notbelong to a single stellar association. We find evidence of theexistence of three coherent structures at distances of 370 pc, 1 kpc,and 2.6-3.2 kpc. The high stellar density toward NGC 2439 is very likelydue to a decreased absorption in this direction, which poses some doubton the reality of the cluster. A comprehensive uvbybeta study of NGC2439 is required to clarify its nature. The spatial distribution of thestars and their reddening are used to characterise the spatialdistribution of the visual extinction in the region. The resultsobtained confirm previously determined constraints on the formationmechanism of interstellar CH+ towards the NGC 2439 field.Table 2 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/372/95
| Estimation of spectral classifications for bright southern stars with interesting Stromgren indices
This paper investigates the degree of success with which uvby photometrycan be applied to predict spectral classifications for 947 A, F, and Gstars brighter than an apparent magnitude of 8.3 and with four-colorindices indicating some kind of interesting, unusual, or peculiarspectrum. One or several possible spectral classifications are estimatedfor each star from photometry alone, double stars are distinguished, andthe estimates are compared with published classifications. The resultsshow that the framework provided by uvby photometry can be extended toinclude most G and K stars, reddened stars, peculiar stars, and certaintypes of double star.
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