- ID:
- ivo://CDS.VizieR/J/A+AS/130/477
- Title:
- uvby{beta} photometry in 3 EUV shadow directions
- Short Name:
- J/A+AS/130/477
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the uvby{beta} data used to locate the dust and derive distances for nearby diffuse interstellar clouds in the EUV shadows lb27-31, lb165-32 and lb329+46 discovered by the Extreme Ultraviolet Explorer. The photometrically derived parallaxes of our program stars are compared to the parallaxes listed in the Hipparcos Catalog. Within the photometric distance limit of 150pc, the photometric parallaxes of 21 ``normal" stars are consistent with the Hipparcos measurements within an uncertainty of 15%. Much as expected for the Stroemgren system. Since all program stars are brighter than V=~11.5 most of them are included in the Tycho photometry. For our sample of ~200 stars we find V_by_ and V_T_ to be consistent. Few stars are common to published uvby{beta} catalogs, ~10, V and the indices compare well apart from {beta} where a zero point difference of 11mmag is noticed.
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Search Results
- ID:
- ivo://CDS.VizieR/J/PASP/121/1326
- Title:
- uvby{beta} photometry in Norma
- Short Name:
- J/PASP/121/1326
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This investigation presents a study of the Galactic structure toward the Norma section of the Milky Way. The field studied is located between 325{deg} and 335{deg} Galactic longitude and -8{deg} to 8{deg} Galactic latitude. New observations in the uvby{beta} system are combined with all uvby{beta} data currently available to collate a sample of 130 O and B stars. A uniform procedure is applied to obtain the color excesses and stellar distances for all of the stars in the sample. The sample is magnitude limited to about V=9.5mag and contains the brightest stars of the open clusters NGC 6087 and Ly 6, the field 2158 of Loden, the OB association Nor OB1, and stars located in the directions of R 103 and R 105.
- ID:
- ivo://CDS.VizieR/J/A+AS/93/373
- Title:
- uvby-beta photometry in SA 203
- Short Name:
- J/A+AS/93/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results are presented of Stromgren uvby(beta) photometry for 213 stars earlier than G0 and brigher than mpg of about 10.7mag in Selected Area 203. The observed area lies close to the geometric center of the Chamaeleon-Musca dark clouds complex. The results yield V, (b-y), m1, c1, and beta on the standard systems, with overall rms errors for one observation of one star of 0.010, 0.004, 0.007, 0.009, and 0.011, respectively.
- ID:
- ivo://CDS.VizieR/J/A+AS/104/557
- Title:
- uvby-beta photometry in star-forming regions
- Short Name:
- J/A+AS/104/557
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/PASP/108/772
- Title:
- uvby-{beta} photometry of A and F southern stars
- Short Name:
- J/PASP/108/772
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric color excesses and distances plus heliocentric coordinates are calculated for 3762 southern A and early-F stars. The present results, combined with those previously published for the Northern Hemisphere, complete the coverage of the spatial distribution of interstellar reddening in the entire solar neighborhood. The new reddening maps show that the interstellar matter within 300pc of the Sun forms a single very large cloud complex that is somewhat asymmetrical with respect to both the galactic center and the galactic plane. This complex is characterized by pronounced local irregularities in both density and spatial extent. The observations further indicate that (1) the cloud complex is not associated with Gould's belt; (2) there exist large regions of the sky devoid of dust; (3) interstellar reddening is negligible at the galactic poles; (4) the role of intercloud dust in the Southern Hemisphere is minor although more important than in the Northern Hemisphere; (5) the Sun is not located in a dust-free, spherically symmetric bubble as previously thought; and (6) the Sun is, however, located in an elongated dust-free region known as the "local trough."
- ID:
- ivo://CDS.VizieR/J/A+A/528/A148
- Title:
- uvby{beta} photometry of early type stars
- Short Name:
- J/A+A/528/A148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The {beta} Cephei stars and slowly pulsating B (SPB) stars are massive main sequence variables. The strength of their pulsational driving strongly depends on the opacity of iron-group elements. As many of those stars naturally occur in young open clusters, whose metallicities can be determined in several fundamental ways, it is logical to study the incidence of pulsation in several young open clusters. To provide the foundation for such an investigation, Stroemgren-Crawford uvby{beta} photometry of open cluster target stars was carried out to determine effective temperatures, luminosities, and therefore cluster memberships. In the course of three observing runs, uvby{beta} photometry for 168 target stars was acquired and transformed into the standard system by measurements of 117 standard stars. The list of target stars also included some known cluster and field {beta} Cephei stars, as well as {beta} Cephei and SPB candidates that are targets of the asteroseismic part of the Kepler satellite mission. The uvby{beta} photometric results are presented. The data are shown to be on the standard system, and the properties of the target stars are discussed: 140 of these are indeed OB stars, a total of 101 targets lie within the {beta} Cephei and/or SPB star instability strips, and each investigated cluster contains such potential pulsators. These measurements will be taken advantage of in a number of subsequent publications.
- ID:
- ivo://CDS.VizieR/J/A+A/394/479
- Title:
- uvby{beta} photometry of h and chi Per
- Short Name:
- J/A+A/394/479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD uvby{beta} photometry for stars in the nuclei of the young double cluster {h} and {chi} Persei. We find that the reddening is highly variable through the {h} Per nucleus, increasing from west to east, with values ranging from E(b-y)=0.328+/-0.022 in the western part to E(b-y)=0.465+/-0.025 in the south-east. Towards {chi} Persei the reddening is fairly constant, with E(b-y)=0.398+/-0.025. Both clusters share a common distance modulus of 11.7+/-0.1mag, and an age of logt=7.10+/-0.05 years.
- ID:
- ivo://CDS.VizieR/J/A+A/373/625
- Title:
- uvby{beta} photometry of lambda Bootis stars
- Short Name:
- J/A+A/373/625
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Lambda Bootis stars comprise only a small number of all A-type stars and are characterized as nonmagnetic, Population I, late B to early F-type dwarfs which show significant underabundances of metals whereas the light elements (C, N, O and S) are almost normal abundant compared to the Sun. In the second paper on a spectroscopic survey for lambda Bootis stars, we present the spectral classifications of all program stars observed. These stars were selected on the basis of their Stromgren uvbybeta colors as lambda Bootis candidates. In total, 708 objects in six open clusters, the Orion OB1 association and the Galactic field were classified. In addition, nine serendipity non-candidates in the vicinity of our program stars as well as 15 Guide Star Catalogue stars were observed resulting in a total of 732 classified stars. The 15 objects from the Guide Star Catalogue are part of a program for the classification of apparent variable stars from the Fine Guidance Sensors of the Hubble Space Telescope. A grid of 105 MK standard as well as ``pathological'' stars guarantees a precise classification. A comparison of our spectral classification with the extensive work of Abt & Morrell (1995, Cat. <J/ApJS/99/135>) shows no significant differences. The derived types are 0.23+/-0.09 (rms error per measurement) subclasses later and 0.30+/-0.08 luminosity classes more luminous than those of Abt & Morrell (1995, Cat. <J/ApJS/99/135>)) based on a sample of 160 objects in common. The estimated errors of the means are +/-0.1 subclasses. The characteristics of our sample are discussed in respect to the distribution on the sky, apparent visual magnitudes and Stromgren uvbybeta colors. Table 2 lists all observed Galactic field stars.
- ID:
- ivo://CDS.VizieR/II/180
- Title:
- uvby-beta photometry of metal-poor stars
- Short Name:
- II/180
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the calibrations derived by Schuster and Nissen (=1989A&A...221...65S), the interstellar color excesses, E(b-y), and the metallicities, [Fe/H], have been determined for the 711 high velocity and metal-poor stars in the catalogue of uvby-beta photometry (=1988A&AS...73..225S). 220 of these listed in table1 turn out to be halo stars according to the criterion [Fe/H] <= -1.0. About 15% of the halo stars have colors that are significantly affected by interstellar reddening, i.e. E(b-y) > 0.025. The distributions in the c0-(b-y)0 diagram of the halo stars grouped according to [Fe/H], have well defined turn-off points. From the Teff values of these points a minimum age of 18-20 Gyr for the halo stars is determined. However, this age may be 2-3 Gyr too high due to a possible systematic error in Teff for the stellar models used. Relative ages of 77 halo stars in the turn-off region of the c0-(b-y)0 diagram are derived using the isochrones VandenBerg and Bell (=1985ApJS...58..561V). Assuming that the O/Fe abundance ratio is constant in halo stars, evidence of a cosmic age scatter of +/-2.5Gyr at a given metallicity is found. Furthermore, the mean age of the halo stars is found to decrease smoothly by about 3 Gyr from [Fe/H]= -2.0 to -1.0. These results suggest that a pressure-supported slow uniform collapse controlled the formation and early evolution of the Galaxy. However, the scenario of Searle and Zinn (=1978ApJ...225..357S) is also compatible with the results.
- ID:
- ivo://CDS.VizieR/J/MNRAS/358/66
- Title:
- uvby{beta} photometry of NGC 663
- Short Name:
- J/MNRAS/358/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD uvby{beta} photometry for stars in the central area of the young open cluster NGC 663. We find that the reddening is highly variable, with values ranging from E(b-y)=0.639+/-0.032 in the central part to E(b-y)=0.555+/-0.038 in the south-east. The distance modulus is found to be 11.6+/-0.1mag. (2.1kpc), and the age logt=7.25+/-0.1 years (25+7/-5Myr).
