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- ID:
- ivo://CDS.VizieR/J/A+AS/140/135
- Title:
- Stromgren Photometry in NGC 3680 and NGC 6134
- Short Name:
- J/A+AS/140/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The tables give the results of the Stromgren photometry of the two southern open clusters NGC 6134 and NGC 3680, which were not printed in the paper in A&AS.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/1277
- Title:
- Stromgren photometry in {omega} Cen
- Short Name:
- J/ApJ/706/1277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new intermediate-band Stromgren photometry based on more than 300 u, v, b, y images of the Galactic globular cluster {omega} Cen. Optical data were supplemented with new multiband near-infrared (NIR) photometry (350 J, H, Ks images). The final optical-NIR catalog covers a region of more than 20x20arcmin squared across the cluster center. We use different optical-NIR color-color planes together with proper-motion data available in the literature to identify candidate cluster red-giant (RG) stars. By adopting different Stromgren metallicity indices, we estimate the photometric metallicity for ~4000 RGs, the largest sample ever collected. We identify four distinct subpopulations, namely, MP ([Fe/H]<=-1.49), metal-intermediate (MI; -1.49<[Fe/H]<=-0.93), metal-rich (MR; -0.95<[Fe/H]<=-0.15), and solar metallicity ([Fe/H]~0). The last group includes only a small fraction of stars (~8%+/-5%) and should be confirmed spectroscopically. Moreover, using the difference in metallicity based on different photometric indices, we find that the 19%+/-1% of RGs are candidate CN-strong stars.
- ID:
- ivo://CDS.VizieR/J/AJ/119/2282
- Title:
- Stromgren photometry of IC 4651
- Short Name:
- J/AJ/119/2282
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry of the intermediate-age open cluster IC 4651 on the uvbyH{beta} system is presented and analyzed. By using a combination of the information from the color-magnitude diagram (CMD) and the color-color diagrams, a sample of 98 highly probable main-sequence cluster members with high photometric accuracy is isolated.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/4162
- Title:
- Stromgren photometry of M3 (NGC5272)
- Short Name:
- J/MNRAS/458/4162
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Stroemgren photometry of the Galactic Globular Cluster M3 to study its multiple generations phenomenon. The use of different colour-magnitude diagrams (CMDs) and especially of the notoriously efficient c_y_ index allowed us to detect a double red giant branch in the cluster CMD. After decontamination from fore- and background sources, the two sequences turned out to be equally populated. The two components also show a bimodal radial distribution well corresponding to that predicted by numerical simulations for clusters living in an intermediate dynamical evolutive state and with a population with modified chemical composition that was born more centrally concentrated than the primordial. The analysis of high-resolution spectra quantitatively demonstrates that the two detected sequences correspond to the first (Na-poor) generation and the second (Na-rich) generation, thus confirming the importance of synergy between photometry and spectroscopy.
- ID:
- ivo://CDS.VizieR/J/AJ/129/872
- Title:
- Stromgren photometry of NGC 2243
- Short Name:
- J/AJ/129/872
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry on the intermediate-band uvbyCaH{beta} system is presented for the metal-deficient open cluster NGC 2243.
- ID:
- ivo://CDS.VizieR/J/AJ/120/3111
- Title:
- Stromgren photometry of NGC 6397
- Short Name:
- J/AJ/120/3111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry extending below the turnoff of the globular cluster NGC 6397 on the uvbyH{beta} system is presented and analyzed. Restricting the sample to stars with small photometric errors and highly probable cluster membership, the reddening from approximately 1500 stars at the turnoff is E(b-y)=0.127+/-0.002 (standard error of the mean), equivalent to E(B-V)=0.179+/-0.003. The photometric abundance for the same sample, on the revised spectroscopic scale for globular clusters, is [Fe/H]=-1.82+/-0.04 (standard error of the mean). From 220 cluster red giants, well-defined relations are established for m_1_ and c_1_ as a function of b-y.
- ID:
- ivo://CDS.VizieR/J/AJ/125/1383
- Title:
- Stromgren photometry of NGC 6253
- Short Name:
- J/AJ/125/1383
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry on the intermediate-band uvbyCaH system is presented for the old open cluster NGC 6253. Despite a high level of field star contamination because of its location toward the Galactic center, combination of the data from the multiple color indices with the core cluster sample derived from radial star counts leads to the identification of a set of highly probable, single cluster members.
- ID:
- ivo://CDS.VizieR/J/AJ/131/461
- Title:
- Stromgren photometry of NGC 2420
- Short Name:
- J/AJ/131/461
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry on the intermediate-band vbyCaH{beta} system is presented for the metal-deficient open cluster NGC 2420. Restricting the data to probable single members of the cluster using the CMD and the photometric indices alone generates a sample of 106 stars at the cluster turnoff.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A119
- Title:
- Stromgren v photometry of {sigma} Lup
- Short Name:
- J/A+A/545/A119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Magnetic early B-type stars are rare. Indirect indicators are needed to identify them before investing in time-intensive spectropolarimetric observations. We use the strongest indirect indicator of a magnetic field in B stars, which is periodic variability of ultraviolet (UV) stellar wind lines occurring symmetric about the approximate rest wavelength. Our aim is to identify probable magnetic candidates which would become targets for follow-up spectropolarimetry to search for a magnetic field. From the UV wind line variability the B1/B2V star sigma Lupi emerged as a new magnetic candidate star. AAT spectropolarimetric measurements with SEMPOL were obtained. The longitudinal component of the magnetic field integrated over the visible surface of the star was determined with the least- squares deconvolution method. The UV line variations of sigma Lupi are similar to what is known in magnetic B stars, but no periodicity could be determined. We detected a varying longitudinal magnetic field with amplitude of about 100G with error bars of typically 20G, which supports an oblique magnetic-rotator configuration. The equivalent width variations of the UV lines, the magnetic and the optical-line variations are consistent with the photometric period of 3.02d, which we identify with the rotation period of the star. Additional observations with ESPaDOnS attached to the CFHT confirmed this discovery, and allowed the determination of a precise magnetic period. Analysis revealed that sigma Lupi is a helium-strong star, with an enhanced nitrogen abundance and an underabundance of carbon, and has a chemically spotted surface. Conclusions. sigma Lupi is a magnetic oblique rotator, and is a He-strong star. Like in other magnetic B stars the UV wind emission appears to originate close to the magnetic equatorial plane, with maximum emission occurring when a magnetic pole points towards the Earth. The 3.01972+/-0.00043d magnetic rotation period is consistent with the photometric period, with maximum light corresponding to maximum magnetic field.
