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A spectroscopic survey for lambda Bootis stars. II. The observational data
lambda Bootis stars comprise only a small number of all A-type stars andare characterized as nonmagnetic, Population i, late B to early F-typedwarfs which show significant underabundances of metals whereas thelight elements (C, N, O and S) are almost normal abundant compared tothe Sun. In the second paper on a spectroscopic survey for lambda Bootisstars, we present the spectral classifications of all program starsobserved. These stars were selected on the basis of their Strömgrenuvbybeta colors as lambda Bootis candidates. In total, 708 objects insix open clusters, the Orion OB1 association and the Galactic field wereclassified. In addition, 9 serendipity non-candidates in the vicinity ofour program stars as well as 15 Guide Star Catalogue stars were observedresulting in a total of 732 classified stars. The 15 objects from theGuide Star Catalogue are part of a program for the classification ofapparent variable stars from the Fine Guidance Sensors of the HubbleSpace Telescope. A grid of 105 MK standard as well as ``pathological''stars guarantees a precise classification. A comparison of our spectralclassification with the extensive work of Abt & Morrell(\cite{Abt95}) shows no significant differences. The derived types are0.23 +/- 0.09 (rms error per measurement) subclasses later and 0.30 +/-0.08 luminosity classes more luminous than those of Abt & Morrell(\cite{Abt95}) based on a sample of 160 objects in common. The estimatederrors of the means are +/- 0.1 subclasses. The characteristics of oursample are discussed in respect to the distribution on the sky, apparentvisual magnitudes and Strömgren uvbybeta colors. Based onobservations from the Observatoire de Haute-Provence, OsservatorioAstronomico di Padova-Asiago, Observatório do Pico dosDias-LNA/CNPq/MCT, Chews Ridge Observatory (MIRA) and University ofToronto Southern Observatory (Las Campanas).
| OB Stellar Associations in the Direction of Centaurus OB2
One hundred eighty-five mostly OB and some early A-type stars aredetected at 1640 Å with the ultraviolet telescope Glazar aboardthe Mir space station in an area of about 8 deg^2 in the directiontoward the stellar association Cen OB2. The limiting stellar magnitudem_1640 of the observations is about 8.5 mag. Stellar associations atdistances of 360, 850, 1500, 2300, 2700, 4000, and 6700 pc are detectedby the study of the space distribution of 111 of the observed stars withknown spectral types. It was shown that the cluster IC 2944 is locatedat a distance of 2200 pc. It is suggested that the extinction ofemission of stars in the content of the cluster is due to small dustclouds or even to circumstellar dust shells. It is shown also that thedust matter is practically absent in the space between stellarassociations and that the extinction of some stars within stellarassociations is caused by relatively small dust clouds, in which thestars are embedded. Two of the detected stars, HD 101316 and HD 101967,are of relatively late spectral types and therefore probably have hotdwarf or subdwarf companions.
| OB Stellar Associations in Crux. I. Observations With the Glazar Space Telescope
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....111..299T&db_key=AST
| A homogeneous catalog of new UBV and H-beta photometry of B- and A-type stars in and around the Scorpius-Centaurus OB association
B- and A-type stars in and near the Sco-Cen OB association areinvestigated with UBV and H-beta photometry to acquire data relevant tothe luminosity function of Sco-Cen. The measurements generally consistof two 10-s integrations of U, B, V, (W, N) filters, and theobservations are corrected iteratively for atmospheric extinction andinstrumental response. The data presented give the mean V magnitude,mean B-V, mean U-B, and the estimated uncertainties for these values.The catalog provides a homogeneous catalog of data for a large fieldwith stellar objects delineating membership to the association Sco-Cenand that affect the luminosity function of the aggregate.
| Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
| Photometric variability of some CP stars
The photometric data relative to twenty-three southern CP stars havebeen re-analyzed. New or improved parameters of the lightcurves arepresented for eleven of them.
| A photoelectric investigation of light variability in AP stars
A study of the light variability of a number of peculiar A stars, mainlyin Stromgren colors u and v and in peculiarity index Delta-a, leads tothe proposal of the following light variability periods: (1) HD 5601,1.11 days; (2) HD 19712, 2.19 days; (3) HD 30849, 15.86 days; (4) HD38823, 8.64 days; (5) HD 53116, 11.98 or 18.10 days; (6) HD 56022, 0.92days; and (7) HD 81009, 33.97 days. In addition, evidence is given forvariability of HD 94660 on a time scale on the order of months or years,and it is shown that the rotation period proposed by Borra andLandstreet (1980) for HD 25267 is not supported by the light variationsobserved. The character of Delta-a variability is discussed.
| Uvby-Beta Photometry of Equatorial and Southern Bright Stars - Part Two
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&AS...42..311H&db_key=AST
| UVBY BET photometry of equatorial and southern bright stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977A&AS...27...47H&db_key=AST
| Infrared Surveys of the Southern Milky way. I. Suspected Supergiant Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJ...156L..37A&db_key=AST
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