- ID:
- ivo://CDS.VizieR/J/MNRAS/419/1350
- Title:
- Red giants abundances in 4 open clusters
- Short Name:
- J/MNRAS/419/1350
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analysed high-dispersion echelle spectra (R>~50000) of red giant members for four open clusters to derive abundances for many elements. The spread in temperatures and gravities being very small among the red giants nearly the same stellar lines were employed thereby reducing the random errors. The errors of average abundance for the cluster were generally in the range 0.02-0.07dex. Our present sample covers Galactocentric distances of 8.3-10.5kpc. The [Fe/H] values are -0.02+/-0.05 for NGC 752, -0.07+/-0.06 for NGC 2360, -0.11+/-0.05 for NGC 1817 and -0.19+/-0.06 for NGC 2506. Abundances relative to Fe for elements from Na to Eu are equal within measurement uncertainties to published abundances for thin-disc giants in the field. This supports the view that field stars come from disrupted open clusters.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/137/4753
- Title:
- Red giants equivalent widths in 4 open clusters
- Short Name:
- J/AJ/137/4753
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of high-dispersion echelle spectra of seven giant stars in the ~1-2Gyr old open clusters NGC 1817, NGC 1883, NGC 2141, and NGC 2158. Abundances were determined relative to the bright, mildly metal-poor disk giant Arcturus.
- ID:
- ivo://CDS.VizieR/J/A+A/299/53
- Title:
- Red giants in NGC 3680 and IC 4651
- Short Name:
- J/A+A/299/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/547/A15
- Title:
- Red supergiants around Stephenson 2
- Short Name:
- J/A+A/547/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several clusters of red supergiants have been discovered in a small region of the Milky Way close to the base of the Scutum-Crux Arm and the tip of the Long Bar. Population synthesis models indicate that they must be very massive to harbour so many supergiants. Amongst these clusters, Stephenson 2, with a core grouping of 26 red supergiants, is a strong candidate to be the most massive young cluster in the Galaxy. Stephenson 2 is located close to a region where a strong over-density of red supergiants had been found. We explore the actual cluster size and its possible connection to this over-density. Taking advantage of Virtual Observatory tools, we have performed a cross-match between the DENIS, USNO-B1 and 2MASS catalogues to identify candidate obscured luminous red stars around Stephenson 2, and in a control nearby region. More than 600 infrared bright stars fulfill our colour criteria, with the vast majority having a counterpart in the I band and >400 being sufficiently bright in I to allow observation with a 4-m class telescope. We observed a subsample of ~250 stars, using the multi-object, wide-field, fibre spectrograph AF2 on the WHT telescope in La Palma, obtaining intermediate-resolution spectroscopy in the 7500-9000{AA} range. We derived spectral types and luminosity classes for all these objects and measured their radial velocities.
- ID:
- ivo://CDS.VizieR/J/ApJ/671/781
- Title:
- Red supergiants in Sct-Cru Galactic arm
- Short Name:
- J/ApJ/671/781
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the unprecedented red supergiant (RSG) population of a massive young cluster, located at the base of the Scutum-Crux Galactic arm. We identify candidate cluster RSGs based on 2MASS photometry and medium-resolution spectroscopy. With follow-up high-resolution spectroscopy, we use CO band-head equivalent width and high-precision radial velocity measurements to identify a core grouping of 26 physically associated RSGs-the largest such cluster known to date.
- ID:
- ivo://CDS.VizieR/J/A+AS/116/75
- Title:
- Region of the open cluster Tr 14
- Short Name:
- J/A+AS/116/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBVRI CCD imaging photometry down to approximately V=19mag in the area of the very young open cluster Tr 14. Our results confirm the existence of an anomalous extinction law in the area if it is interpreted in terms of the UBVRI photometry. According to our analysis the cluster distance is d=3100 (V_0_-M_V_=12.50mag) and its age is 1.5+/-.5x10^6^y. We want to draw the attention on stars which, from the observed magnitude-spread at constant color, could be stars in an early stage of evolution. In that case, the observed spread leads to assume that the process of star formation in Tr 14 is continuous whereas, from pre-main sequence evolutionary tracks, a duration of about 5x10^6^y is deduced for it. The computation of the cluster initial mass function reveals a flat slop e even though it still compares to a Salpeter law. At the same time, we found a spatial variation of the cluster IMF, which could be explained by mass segregation in the star formation process. The cluster youth and its compact appearance seem to confirm that it is far from virial equilibrium. The observed tot al cluster mass is around 2000M_{sun}_ and its core contains about 40% of the total.
- ID:
- ivo://CDS.VizieR/J/PAZh/41/367
- Title:
- Relative proper motions in NGC 6800
- Short Name:
- J/PAZh/41/367
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a comprehensive study of the Galactic open cluster NGC 6800 are presented. The positions of stars to a limiting magnitude B<=16.5mag in an 80x80 arcmin field centered at the cluster were measured on eight plates from the Pulkovo normal astrograph with a maximum epoch difference of 57 years. The measurements were performed with the Pulkovo "Fantasy" automated measuring system. The corresponding field from the 2MASS catalogue was used as an additional plate. As a result, the relative proper motions of stars were obtained with a root-mean-square error of 3.0 mas/yr. A catalogue of BV and JHK magnitudes for objects in the investigated region was compiled from available published resources. The astrometric selection of cluster members was made by the maximum likelihood method. An individual cluster membership probability of a star P>=60% served as the first selection criterion. The position of a star on the photometric color-magnitude (V-(B-V)), J-(J-Ks)) diagrams was considered as the second selection criterion. On the basis of these criteria, it was established that 109 stars are members of NGC 6800. These data were used to refine the physical parameters of the cluster: the mean reddening E(B-V)=0.40mag, the true distance modulus (V-Mv)0=10.05mag, and the cluster age ~250Myr. The luminosity and mass functions were constructed. The position of the center of the cluster NGC 6800 was improved: RA=19:27:11.2 and DE=+25:07:24 (2000).
- ID:
- ivo://CDS.VizieR/J/A+A/597/A90
- Title:
- rho Oph proper motions and photometry
- Short Name:
- J/A+A/597/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim at performing a kinematic census of young stellar objects (YSOs) in the rho Ophiuchi F core and partially in the E core of the L1688 dark cloud. We run a proper motion program at the ESO New Technology Telescope (NTT) with the Son of ISAAC (SOFI) instrument over nine years in the near-infrared. We complemented these observations with various public image databases to enlarge the time base of observations and the field of investigation to 0.5{deg}x0.5{deg}. We derived positions and proper motions for 2213 objects. From these, 607 proper motions were derived from SOFI observations with a ~1.8mas/yr accuracy while the remaining objects were measured only from auxiliary data with a mean precision of about 3mas/yr. We performed a kinematic analysis of the most accurate proper motions derived in this work, which allowed us to separate cluster members from field stars and to derive the mean properties of the cluster. From the kinematic analysis we derived a list of 68 members and 14 candidate members, comprising 26 new objects with a high membership probability.
- ID:
- ivo://CDS.VizieR/J/A+AS/119/413
- Title:
- RI and Teff of stars in NGC 2477
- Short Name:
- J/A+AS/119/413
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Trough photometric methods we have constructed the luminosity function for the southern open cluster NGC 2477 down to M_v_=~12. We present R-I color-magnitude diagrams and near-infrared color-color diagrams, which allow us to separate statistically the cluster stars from the field ones, numerous because of the galactic latitude of the cluster. Our luminosity function (LF) reproduces some features obtained by other authors, namely, a dip at M_v_=~7, and a probable maximum at M_v_=~12. The method developed to separate cluster stars from field stars could be of interest to other astronomical problems.
- ID:
- ivo://CDS.VizieR/J/AN/325/705
- Title:
- RIJHKs of low-mass stars in sigma Ori
- Short Name:
- J/AN/325/705
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an RI photometric survey covering an area of 430 arcmin^2^ around the multiple star sigma Orionis. The observations were conducted with the 0.8m IAC-80 Telescope at the Teide Observatory. The survey limiting R and I magnitudes are 22.5 and 21, and completeness magnitudes 21 and 20, respectively. We have selected 53 candidates from the I vs. R-I colour-magnitude diagram (I=14-20) that follow the previously known photometric sequence of the cluster. Adopting an age of 2-4 Myr for the cluster, we find that these objects span a mass range from 0.35M_{sun}_ to 0.015M_{sun}_. We have performed J-band photometry of 52 candidates and K_s photometry for 12 of them, with the result that 50 follow the expected infrared sequence for the cluster, thus confirming with great confidence that the majority of the candidates are bona fide members. JHK_s photometry from the Two Micron All Sky Survey (2MASS, Cat. <II/246>) is available for 50 of the candidates and are in good agreement with our data. Out of 48 candidates, which have photometric accuracies better than 0.1mag in all bands, only three appear to show near-infrared excesses.