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- ID:
- ivo://CDS.VizieR/J/ApJS/161/118
- Title:
- byH{alpha} photometry in open clusters
- Short Name:
- J/ApJS/161/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Be stars are a class of rapidly rotating B stars with circumstellar disks that cause Balmer and other line emission. There are three possible reasons for the rapid rotation of Be stars: they may have been born as rapid rotators, spun up by binary mass transfer, or spun up during the main-sequence (MS) evolution of B stars. To test the various formation scenarios, we have conducted a photometric survey of 55 open clusters in the southern sky. Of these, five clusters are probably not physically associated groups and our results for two other clusters are not reliable, but we identify 52 definite Be stars and an additional 129 Be candidates in the remaining clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/622/1052
- Title:
- byH{alpha} photometry of NGC 3766
- Short Name:
- J/ApJ/622/1052
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a technique to identify Be stars in open clusters using Stroemgren b, y, and narrowband H{alpha} photometry. We first identify the B-type stars of the cluster using a theoretical isochrone fit to the (b-y, y) color-magnitude diagram. The strongest Be stars are easily identified in a (b-y, y-H{alpha}) color-color diagram, but those with weaker H{alpha} emission (classified as possible Be star detections) may be confused with evolved or foreground stars. Here we present such photometry plus H{alpha} spectroscopy of members of the cluster NGC 3766 to demonstrate the accuracy of our technique.
- ID:
- ivo://CDS.VizieR/J/PAZh/44/383
- Title:
- Byurakan-IRAS galaxies (BIG) with SDSS spectra
- Short Name:
- J/PAZh/44/383
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The sample of Byurakan-IRAS galaxies (BIG) has been created based on optical identifications of IRAS Point Source Catalog (PSC) at high galactic latitudes. As a result, 1178 galaxies have been identified. 172 of them have been observed spectroscopically with Byurakan Astrophysical Observatory (BAO, Armenia) 2.6m, Special Astrophysical Observatory (SAO, Russia) 6m and Observatoire de Haute Provence (OHP, France) 1.93m telescopes. Later on, spectra were obtained for more 83 BIG objects in Sloan Digital Sky Survey (SDSS). We have extracted and studied these spectra, classified them and measured spectral features. Diagnostic diagrams have been built to distinguish starbursts (SB), LINERs and Seyfert galaxies. Cross-correlations were made for these objects with multiwavelength (MW) catalogues and their physical properties were studied. Among these 83 objects, 55 HII, 8 Seyfert galaxies, 2 LINERs, 4 other AGN, 6 composite spectrum objects, and 8 other emission-line galaxies have been revealed. Three of these objects are Ultra-Luminous InfraRed Galaxies (ULIRG).
- ID:
- ivo://CDS.VizieR/J/A+A/507/131
- Title:
- BzJK observations around radio galaxies
- Short Name:
- J/A+A/507/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the environments of two radio galaxies at z~1.5, 7C 1751+6809 and 7C 1756+6520, using deep optical and near-infrared imaging. Our data cover 15x15arcmin^2^ fields around the radio galaxies. We develop and apply BzK color criteria to select cluster member candidates around the radio galaxies and find no evidence of an overdensity of red galaxies within 2Mpc of 7C 1751+6809. In contrast, 7C 1756+6520 shows a significant overdensity of red galaxies within 2Mpc of the radio galaxy, by a factor of 3.1+/-0.8 relative to the four MUSYC fields. At small separation (r<6"), this radio galaxy also has one z>1.4 evolved galaxy candidate, one z>1.4 star-forming galaxy candidate, and an AGN candidate (at indeterminate redshift).
- ID:
- ivo://CDS.VizieR/J/ApJ/462/241
- Title:
- Ca abundance for Omega Cen red giants
- Short Name:
- J/ApJ/462/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an unbiased catalog of calcium abundances for 517 red giants brighter than M_V_~-1 in the chemically inhomogeneous globular cluster omega Centauri. The basic features of the abundance distribution are as follows: (1) few, if any, stars exist on the giant branch of omega Cen with [Ca/H] less than -1.6; (2) there is a well-defined peak in the distribution at [Ca/H]=-1.4, with a long tail stretching up to ~[Ca/H]~-0.3; and (3) the distribution is bimodal with a second smaller peak in the distribution at [Ca/H]=-0.9.
- ID:
- ivo://CDS.VizieR/J/A+A/526/A71
- Title:
- C abundances in G and K nearby stars
- Short Name:
- J/A+A/526/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a determination of photospheric parameters and carbon abundances for a sample of 172 G and K dwarf, subgiant, and giant stars with and without detected planets in the solar neighbourhood. The analysis was based on high signal-to-noise ratio and high resolution spectra observed with the ELODIE spectrograph (Haute Provence Observatory, France) and for which the observational data were publicly available. We intend to contribute precise and homogeneous C abundances in studies that compare the behaviour of light elements in stars with and without planets. This will bring new arguments to the discussion of possible anomalies that have been suggested and will contribute to a better understanding of different planetary formation process.
- ID:
- ivo://CDS.VizieR/J/ApJS/219/7
- Title:
- Ca,by photometry in globular clusters. I. M22
- Short Name:
- J/ApJS/219/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the multiple stellar populations in one of the peculiar globular clusters (GCs), M22, using new ground-based wide-field Ca by and Hubble Space Telescope Wide-Field Camera 3 photometry with equivalent passbands, confirming our previous result that M22 has a distinctive red giant branch (RGB) split mainly due to the difference in metal abundances. We also make use of radial velocity measurements by others of the large number of cluster membership stars. Our main results are the following. (1) The RGB and the subgiant branch number ratios show that the calcium-weak (Ca-w) group is the dominant population of the cluster. However, an irreconcilable difference can be seen in the rather simple classification into two horizontal branches by others. (2) Each group has its own CN-CH anticorrelation. However, the alleged CN-CH positive correlation is likely illusory. (3) The location of the RGB bump of the calcium-strong (Ca-s) group is significantly fainter, which may pose a challenge to the helium enhancement scenario in the Ca-s group. (4) The positions of the centers are similar. (5) The Ca-w group is slightly more centrally concentrated, whereas the Ca-s is more elongated at larger radii. (6) The mean radial velocities for both groups are similar, but the Ca-s group has a larger velocity dispersion. (7) The Ca-s group rotates faster. The plausible scenario for the formation of M22 is that it formed via a merger of two GCs in a dwarf galaxy environment and accreted later to our Galaxy.
- ID:
- ivo://CDS.VizieR/J/AJ/119/1824
- Title:
- Caby photometry of {Omega} Centauri
- Short Name:
- J/AJ/119/1824
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new measurements of the metallicity of 131 RR Lyrae stars in the globular cluster {omega} Centauri, using the hk index of the Caby photometric system. The hk method has distinct advantages over {delta}S and other techniques in determining the metallicity of RR Lyrae stars and has allowed us to obtain the most complete and homogeneous metallicity data to date for the RR Lyrae stars in this cluster. For RR Lyrae stars in common with the {delta}S observations of Butler, Dickens, & Epps (1978ApJ...225..148B) and Gratton, Tornambe, & Ortolani (1986A&A...169..111G), we have found that our metallicities, [Fe/H]_hk_, deviate systematically from their {delta}S metallicity, while our [Fe/H]_hk_ for well-observed, field RR_ab_ stars are consistent with previous spectroscopic measurements.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/L23
- Title:
- ^48^Ca heterogeneity in differentiated meteorites
- Short Name:
- J/ApJ/743/L23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Isotopic heterogeneities of ^48^Ca have been found in numerous bulk meteorites that are correlated with ^50^Ti and ^54^Cr anomalies among differentiated planetary bodies, and the results suggest that a rare subset of neutron-rich Type Ia supernova (nSN Ia) was responsible for contributing these neutron-rich iron-group isotopes into the solar system (SS). The heterogeneity of these isotopes found in differentiated meteorites indicates that the isotopic compositions of the bulk SS are not uniform, and there are significant amounts of nSNe Ia dust incompletely mixed with the rest of SS materials during planetary formation. Combined with the data of now-extinct short-lived nuclide ^60^Fe, which can be produced more efficiently from an nSN Ia than a Type II supernova ejecta, the observed planetary-scale isotopic heterogeneity probably reflects a late input of stellar dust grains with neutron-rich nuclear statistical equilibrium nuclides into the early SS.
