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The Carina spiral feature: Strömgren-? photometry approach. II. Distances and space distribution of the O and B stars
Aims: In recent years a significant development has becomeevident in the study of the stellar structure of the Galactic disk. Thisis especially true for the 3rd Galactic quadrant, where the stellarpopulation was extensively investigated beyond 10 kpc, revealing detailsabout the warped geometry of the thin and thick disks and outer arm. The4th Galactic quadrant offers even better opportunity to follow thedistribution of the young stellar populace to a large distance, sincethe line of sight is parallel to the largest single segment of a spiralarm seen from our position in the Galaxy: the Carina spiral feature.This paper further contributes to the study of the structure of theGalactic disk in the direction of Carina field utilizing homogeneousphotometric distances of a sample of about 600 bright early-type starsseen in this direction up to 6 kpc. Methods: The derived stellardistances are based on uvby? photometry. All O and B type starswith uvby? data presently available are included in the study. Results: The photometry-derived parameters allow us to study thestructure and characteristics of this segment of the Carina arm. We findthat the stellar distribution is consistent with a location of theapparent edge of the arm at l = 287°. Toward the edge of the arm thewarp of the Galactic plane can be traced up to 6 kpc where it reachesnegative 200 pc. The field toward the edge seems to be much more complexthan harboring just one OB association, and it is likely that some ofthe apparent concentrations in this field represent parts of longsegments of the edge. In the 284° longitude range an interarm spaceabout 1 kpc wide is found beyond 850 pc from the Sun. The giantmolecular clouds and open clusters do not follow the edge of the arm asdefined by the OB stars and indicate a possible presence of an agegradient in a direction perpendicular to the formal Galactic plane.Table 4 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/514/A59
| Searching for unknown open clusters in the Tycho-2 catalog
We present 11 new open cluster candidates found in a systematic searchfor unknown star clusters using the astrometric and photometric dataincluded in the Tycho 2 catalog. The possible existence of these stellaraggregates is supported by the analysis of proper motions,color-magnitude diagrams, stellar density distributions, and by thevisual inspection of the Digitized Sky Survey (DSS) plates. With thesetools we were able to determine mean absolute proper motions as well aspreliminary reddenings, distances and ages for the majority of thecandidates. We found that most of them are possibly nearby (closer than~ 600 pc) open clusters never studied before.Based on observations of the ESA Hipparcos satellite.Figures 1 and 2 are only available in electronic form athttp://www.edpsciences.org
| The Carina Spiral Feature: Strömgren-Hβ photometry approach. I. The photometric data-base
A data-base collating all uvbybeta photometry available at present forO-B9 stars brighter than 10th visual magnitude in the field of theCarina Spiral Feature is presented. The completeness and homogeneity ofthe data-base are discussed.Based on CDS data.Table 1 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/410/523
| CCD measurements of visual binaries
CCD measurements of visual double stars were obtained with the ESO 1.5 mdanish reflector. All binaries observed are candidates for the HIPPARCOSInput Catalogue. More than 400 observations have been made in four clearnights. The accuracy obtained is comparable to the accuracy of thephotographic technique, but the observing and reduction times are oneorder of magnitude smaller.
| Photographic measurements of southern double stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985PASP...97..579K&db_key=AST
| A study of visual double stars with early type primaries. IV Astrophysical data
Astrophysical parameters (MK class, color excess, absolute magnitude,distance, effective temperature, mass, and age) are derived fromcalibrations of the uvby-beta indices for the members of 253 doublestars with O or B type primaries and faint secondaries. The photometricspectral classification is compared to the MK classes, and the agreementis very good. The derived data together with spectroscopic and JHKL dataare used for deciding which pairs are likely to be physical and whichare optical, and it is shown that 98 (34 percent) of the secondaries arelikely to be members of physical systems. For 90 percent of the physicalpairs the projected separation between the components is less than25,000 AU. A majority of the physical secondaries are late-type stars,and 50 percent of them are contracting towards the zero-agemain-sequence. Also presented are new uvby-beta data for 43 secondariesand a computer program for determining astrophysical parameters fromuvby-beta data.
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