- ID:
- ivo://CDS.VizieR/J/AJ/157/49
- Title:
- Stroemgren photometry in the field of NGC 1978
- Short Name:
- J/AJ/157/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the spread of [Fe/H] values in the massive Large Magellanic Cloud cluster NGC 1978, recently confirmed to harbor multiple populations of nearly the same age. We used accurate Stroemgren photometry of carefully selected cluster red giant branch stars along with a high-dispersion spectroscopy-based calibration of the metallicity-sensitive index m_1_. Once we accounted for the photometry quality, assessed from extensive artificial star tests to trace the photometric uncertainties as a function of the position of the cluster's center as well as the stellar brightness, and those from the metallicity calibration, we found that NGC 1978 exhibits a small metallicity spread of 0.035 dex (+/-0.019-0.023), depending on whether stars with individual {sigma}[Fe/H]=<0.15 dex or those located in the cluster's outer areas are considered. Such a spread in [Fe/H] is consistent with a cluster formation model with self-enrichment, if mass loss higher than 90% due to stellar evolutionary and galactic tidal effects is assumed. Nevertheless, scenarios in which the apparent [Fe/H] variation reflects CN abundance anomalies or less extreme mass-loss models with environmentally dependent self-enrichment should not be ruled out.
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- ID:
- ivo://CDS.VizieR/J/A+A/565/A8
- Title:
- Stroemgren photometry near NGC 6528
- Short Name:
- J/A+A/565/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Stroemgren and near-infrared (NIR) photometry of the bulge cluster NGC 6528 and its surrounding field in Baade's Window. uvby images were collected with EFOSC2 on the New Technology Telescope (NTT, La Silla, ESO). The NIR catalogs are based on J,K-band VIRCAM at VISTA (Paranal, ESO) and SOFI at NTT photometry. We matched the aforementioned data sets with Hubble Space Telescope photometry to obtain proper-motion-cleaned samples of NGC 6528 and bulge stars. Furthermore, we were able to correct the Stroemgren-NIR photometry for differential reddening. The huge color sensitivity of the Stroemgren-NIR color-magnitude-diagrams (CMDs) helped us in separating age and metallicity effects.
- ID:
- ivo://CDS.VizieR/J/A+A/275/201
- Title:
- Stroemgren photometry of Dwarf Novae
- Short Name:
- J/A+A/275/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 26 dwarf novae was observed in the Stroemgren photometric system. The observations were performed on 3 different seasons in 1986 January, February and July, with a 6-channel photometer attached to the 1.5m telescope if the Observatorio Astronomicao Nacional at San Pedro Martir, Baja California, Mexico. A number of standard stars were observed, and a nearby comparison star was observed for each object.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/4438
- Title:
- Stroemgren photometry of M13
- Short Name:
- J/MNRAS/474/4438
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric study of M13 multiple stellar populations over a wide field of view, covering approximately 6.5 half-light radii, using archival Isaac Newton Telescope observations to build an accurate multiband Stroemgren catalogue. The use of the Stroemgren index cy permits us to separate the multiple populations of M13 on the basis of their position on the red giant branch. The comparison with medium and high resolution spectroscopic analysis confirms the robustness of our selection criterion. To determine the radial distribution of stars in M13, we complemented our data set with Hubble Space Telescope observations of the cluster core, to compensate for the effect of incompleteness affecting the most crowded regions. From the analysis of the radial distributions, we do not find any significant evidence of spatial segregation. Some residuals may be present in the external regions where we observe only a small number of stars. This finding is compatible with the short dynamical time-scale of M13 and represents, to date, one of the few examples of fully spatially mixed multiple populations in a massive globular cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/521/A40
- Title:
- Stroemgren photometry of Milky Way stars
- Short Name:
- J/A+A/521/A40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several large scale photometric and spectroscopic surveys are being undertaken to provide a more detailed picture of the Milky Way. Given the necessity of generalisation in the determination of, e.g., stellar parameters when tens and hundred of thousands of stars are considered it remains important to provide independent, detailed studies to verify the methods used in the surveys.
- ID:
- ivo://CDS.VizieR/J/A+A/403/937
- Title:
- Stroemgren photometry of NGC 6192 and NGC 6451
- Short Name:
- J/A+A/403/937
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have investigated the two open clusters NGC 6192 and NGC 6451 for which widely different reddening values and thus ages and distances via Stroemgren uvby photometry can be found in the literature. Our measurements allow us to disentangle the apparent discrepancies in the literature and to derive new accurate values. From appropriate calibrations we find that the overall abundance for NGC 6192 is about solar whereas a subsolar value for NGC 6451 was estimated. From two previous reported photometrically candidate CP stars, one within NGC 6192 shows Stroemgren indices typical for a B8Si star whereas the other object of NGC 6451 is most probably a foreground G-type star.
- ID:
- ivo://CDS.VizieR/J/A+A/520/A46
- Title:
- Stroemgren photometry of 12 RR Lyrae stars
- Short Name:
- J/A+A/520/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- RR Lyrae stars have been observed to improve the insight into processes at work in their atmospheres. Simultaneous Stroemgren-photometry allows to obtain a rapid sequence of measurements in which photometric indices are unaffected by non-optimum observing conditions. The indices y, b-y, and c1 are used with an established calibration to derive Teff and to determine the gravity, logg_BJ_ from the Balmer jump, throughout the pulsation cycle. By employing the equations for stellar structure, additional parameters can be derived.
- ID:
- ivo://CDS.VizieR/J/AJ/127/1000
- Title:
- Stromgren and Ca photometry of NGC 3680
- Short Name:
- J/AJ/127/1000
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry on the intermediate-band uvbyCaH{beta} system is presented for the open cluster, NGC 3680. Restricting the data to probable cluster members using the color-magnitude diagram (CMD) and the photometric indices alone defines a sample of 34 stars at the cluster turnoff that imply E(b-y)=0.042+/-0.002(s.e.m.) or E(B-V)=0.058+/-0.003(s.e.m.), where the errors refer to internal errors alone. With this reddening, [Fe/H] is derived from both m_1_ and hk using both b-y and H{beta} as the temperature indices.
- ID:
- ivo://CDS.VizieR/J/A+A/462/157
- Title:
- Stromgren CCD photometry in NGC 6383
- Short Name:
- J/A+A/462/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By studying young open clusters, the mechanisms important for star formation over several Myr can be examined. For example, accretion rate as a function of rotational velocity can be investigated. Similarly, sequential star formation triggered by massive stars with high mass-loss rates can be studied in detail. We identified and characterized probable members of NGC 6383, as well as determined cluster parameters. New Stromgren uvby CCD photometry, obtained by us, is presented. This new data, together with Johnson UBV and 2MASS data in the NIR, was used to investigate characteristics of pre- as well as zero age main sequence cluster members. We present Stromgren uvby CCD photometry for 272 stars in the field of NGC 6383 and derive its reddening, E(b-y)=0.21(4)mag, as well as distance, d=1.7(3)kpc from the Sun. Several stars with NIR excess and objects in the domain of the classical Herbig Ae/Be and T Tauri stars were detected. Two previously known variables were identified as rapidly-rotating PMS stars. The field population is clearly separated from the probable members in the color-magnitude diagram. NGC 6383 is a young open cluster, with an age of less than 4Myr, undergoing continuous star formation. True pre-main sequence members might be found down to absolute magnitudes of +6mag, with a variety of rotational velocities and stellar activities.
- ID:
- ivo://CDS.VizieR/J/AJ/133/1585
- Title:
- Stromgren photometry in NGC 6791
- Short Name:
- J/AJ/133/1585
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry on the intermediate-band vbyCaH{beta} system is presented for the metal-rich, old open cluster NGC 6791.
