- ID:
- ivo://CDS.VizieR/J/MNRAS/430/221
- Title:
- NGC 2849 and NGC 6134 UBVI photometry
- Short Name:
- J/MNRAS/430/221
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD photometry of two southern open clusters. As part of the Bologna Open Cluster Chemical Evolution project we obtained BVI and UBVI imaging for NGC 2849 and NGC 6134, respectively. By means of the synthetic colour-magnitude diagram method and using various evolutionary sets of stellar evolution tracks with various metallicities, we determined at the same time age, distance and reddening. We also determined an approximate metallicity for NGC 2849, for which the information is not available from sounder methods like high-resolution spectroscopy. NGC 2849 turned to be 0.85-1.0Gyr old with a solar metallicity. The foreground reddening is E(B-V)=0.28-0.32, and the true distance modulus (m-M)_0_=13.8-13.9. For NGC 6134 we did not obtain fully consistent answers from the V, B-V and V, V-I photometry, an unexpected problem, since both the metallicity and the reddening are known (from high-resolution spectroscopy and the U-B, B-V two colours diagram, respectively). This may either indicate a difficulty of current models (evolutionary tracks and/or models of atmosphere) to accurately reproduce colours, or be related to differences in the metal mixture assumed by the models and those of the clusters. Assuming the spectroscopic abundance and the colour excess [E(B-V)=0.35] from the U-B, B-V plot, we derived a best age between 0.82 and 0.95Gyr and a distance modulus 10.5.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/RMxAA/47.309
- Title:
- NGC 6811 and NGC 6830 uvby-{beta} photometry
- Short Name:
- J/other/RMxAA/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From uvby-{beta} photometry of the open clusters NGC 6811 (75 stars), and NGC 6830 (19 stars) we were able to determine membership of the stars to each cluster, and fix the age and reddening for each. Since several short period stars have recently been found, we have carried out a study of these variables.
- ID:
- ivo://CDS.VizieR/J/ApJ/671/605
- Title:
- NGC 2264 and ONC PMS stars in the infrared
- Short Name:
- J/ApJ/671/605
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of pre-main-sequence star rotation periods reveal slow rotators in young clusters of various ages, indicating that angular momentum is somehow removed from these rotating masses. The mechanism by which spin-up is regulated as young stars contract has been one of the longest standing problems in star formation. Attempts to observationally confirm the prevailing theory that magnetic interaction between the star and its circumstellar disk regulates these rotation periods have produced mixed results. In this paper, we use the unprecedented disk identification capability of the Spitzer Space Telescope to test the star-disk interaction paradigm in two young clusters, NGC 2264 and the Orion Nebula Cluster (ONC).
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/106
- Title:
- NGC5617 and Trumpler 22 stars BV mag and RV
- Short Name:
- J/MNRAS/453/106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using photometry and high-resolution spectroscopy we investigate for the first time the physical connection between the open clusters NGC 5617 and Trumpler 22. Based on new CCD photometry we report their spatial proximity and common age of ~70Myr. Based on high-resolution spectra collected using the HERMES and UCLES spectrographs on the Anglo-Australian telescope, we present radial velocities and abundances for Fe, Na, Mg, Al, Si, Ca, and Ni. The measured radial velocities are -38.63+/-2.25km/s for NGC 5617 and -38.46+/-2.08km/s for Trumpler 22. The mean metallicity of NGC 5617 was found to be [Fe/H]=-0.18+/-0.02 and for Trumpler 22 was found to be [Fe/H]=-0.17+/-0.04. The two clusters share similar abundances across the other elements, indicative of a common chemical enrichment history of these clusters. Together with common motions and ages we confirm that NGC 5617 and Trumpler 22 are a primordial binary cluster pair in the Milky Way.
- ID:
- ivo://CDS.VizieR/J/MNRAS/356/647
- Title:
- NGC 6404 and 6583 VI photometry
- Short Name:
- J/MNRAS/356/647
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on VI charge-coupled device photometry of two fields centred in the region of the open clusters NGC 6404 and 6583 down to V=22.0. So far these clusters have never been studied, and we provide for the first time estimates of their fundamental parameters, namely, radial extent, age, distance and reddening. We find that the radius of NGC 6404 is 2.0-arcmin, as previously proposed, while the radius of NGC 6583 is 1.0 arcmin, significantly lower than previous estimates. Both clusters turn out to be of intermediate age (0.5-1.0Gyr old), and located inside the solar ring, at a Galactocentric distance of about 6.5kpc. These results make these objects very interesting targets for spectroscopic follow-up to measure their metallicity. In fact, they might allow us to enlarge by more than 1 kpc the baseline of the radial abundance gradient in the Galactic disc towards the Galactic Centre direction. This baseline is currently rather narrow especially for clusters of this age.
- ID:
- ivo://CDS.VizieR/J/AJ/122/1486
- Title:
- NGC 2451A proper motions and membership
- Short Name:
- J/AJ/122/1486
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide new evidence that NGC 2451A is undoubtedly a young open cluster, although sparsely populated. New cluster membership has been derived from relative proper motions of 5868 stars. In total, 136 stars down to V~15 5 have membership probability P{mu}>=2%. New CCD BV photometry indicates that about 70 stars are indeed main-sequence stars of NGC 2451A. This is also supported by our measurements of radial velocities. A total of 34 very likely cluster members yield a mean heliocentric radial velocity for NGC 2451A equal to +22.9km/s. The high quality of our BV photometry, a confirmation of cluster membership from proper motions and radial velocities, and a recently obtained metallicity estimate for several cluster stars allow us to perform a precise isochrone fit. The Yale isochrones, updated by the latest available input physics, have been fitted to the cluster's color-magnitude diagram, yielding a distance modulus V_0_-M_V_ in the range 6.35 to 6.38, which is in excellent agreement with the distance modulus (m-M)_0_=6.38 derived from the Hipparcos data recently by van Leeuwen and Robichon et al. (1998, Cat. <J/A+AS/130/157>). We have used the high-resolution spectra acquired using the Hydra multiobject spectrograph at the WIYN telescope (Kitt Peak, Arizona) in 1997 November and 1998 October.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/4185
- Title:
- NGC 2355 BVI photometry
- Short Name:
- J/MNRAS/453/4185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we analyse the evolutionary status and properties of the old open cluster NGC 2355, located in the Galactic anticentre direction, as a part of the long-term programme Bologna Open Clusters Chemical Evolution. NGC 2355 was observed with the Large Binocular Camera at the Large Binocular Telescope using the Bessel B, V, and Ic filters. The cluster parameters have been obtained using the synthetic colour-magnitude diagram method, as done in other papers of this series. Additional spectroscopic observations with the Fibre-fed Echelle Spectrograph at the Nordic Optical Telescope of three giant stars were used to determine the chemical properties of the cluster. Our analysis shows that NGC 2355 has metallicity slightly less than solar, with [Fe/H]=-0.06dex, age between 0.8 and 1Gyr, reddening E(B-V) in the range 0.14-0.19mag, and distance modulus (m-M)0 of about 11mag. We also investigate the abundances of O, Na, Al, {alpha}, iron-peak, and neutron capture elements, showing that NGC 2355 falls within the abundance distribution of similar clusters (same age and metallicity). The Galactocentric distance of NGC 2355 places it at the border between two regimes of metallicity distribution; this makes it an important cluster for the study of the chemical properties and evolution of the disc.
- ID:
- ivo://CDS.VizieR/J/A+A/351/526
- Title:
- NGC 2172 CCD BVI photometry
- Short Name:
- J/A+A/351/526
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new CCD photometry for the young LMC cluster NGC 2172, giving B, V, I magnitudes for more than 600 stars within 70" from the cluster center, down to -approximately- V=21mag. After correction for completeness and field stars contamination, we discuss the cluster HR diagram and the MS luminosity function in the light of current evolutionary theories and in connection with the problem of cluster age.
- ID:
- ivo://CDS.VizieR/J/PASP/117/22
- Title:
- NGC 6318 CCD BVI photometry
- Short Name:
- J/PASP/117/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD BVI photometry for the southern open cluster NGC 6318. The sample consists of 9876 stars measured in an area of 13.6'x13.6', extending down to V~21.5mag. Star counts carried out within and outside the cluster region allowed us to estimate the cluster angular radius as 8'.
- ID:
- ivo://CDS.VizieR/J/other/ApSS/361.126
- Title:
- NGC 6819 CCD UBV photometry
- Short Name:
- J/other/ApSS/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of CCD UBV observations of the open cluster NGC 6819. We calculated the stellar density profile in the cluster's field to determine the structural parameters of NGC 6819. Using the existing astrometric data, we calculated the probabilities of the stars being physical members of the cluster, and used these objects in the determination of the astrophysical parameters of NGC 6819. We inferred the reddening and metallicity of the cluster as E(B-V)=0.130+/-0.035mag and [Fe/H]=+0.051+/-0.020dex, respectively, using the U-B vs B-V two-colour diagram and UV excesses of the F-G type main-sequence stars. We fit the colour-magnitude diagrams of NGC 6819 with the PARSEC isochrones and derived the distance modula, distance and age of the cluster as mu_V=12.22+/-0.10mag, d=2309+/-106pc and t=2.4+/-0.2Gyr, respectively. The parameters of the galactic orbit estimated for NGC 6819 indicate that the cluster is orbiting in a slightly eccentric orbit of e=0.06 with a period of P_orb_=142Myr. The slope of the mass function estimated for the cluster is close to the one found for the stars in the solar neighbourhood.
