- ID:
- ivo://CDS.VizieR/J/A+A/531/A73
- Title:
- NGC 6167 and NGC 6193 multi-photometry
- Short Name:
- J/A+A/531/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Ara OB1a association is a nearby complex in the fourth Galactic quadrant where a number of young/embedded star clusters are projected close to more evolved, intermediate age clusters. It is also rich in interstellar matter, and contains evidences of the interplay between massive stars and their surrounding medium, like the rim HII region NGC 6188. We provide more solid estimates of the fundamental parameters (age and distance) of the two most prominent stellar clusters, NGC 6167 and NGC 6193, that may be used as a basis to study the star formation history of the region. The study is based on a photometric optical survey (UBVIHa) of NGC 6167 and NGC 6193 and their nearby field, complemented with public data from 2MASS-VVV, UCAC3 and IRAC-Spitzer in this region. We produced a uniform photometric catalogue and we estimated more robustly the fundamental parameters for NGC 6167, NGC 6193 and the IRAS 16375-4854 source. As a consequence, all of them are located at approximately the same distance from the Sun in the Sagittarius-Carina Galactic arm. However, the ages we estimated differ widely: NGC 6167 results to be an intermediate-age cluster (20-30Myr), NGC 6193 a very young one (1-5Myr) with PMS, H{alpha} emitters, and class II objects; and the IRAS 16375-4854 source is revealed as the youngest of the three containing several YSOs. These results support a picture in which Ara OB1a is a region where star formation has proceeded for several tens of Myr up to the present. The difference in ages of different stellar groups can be interpreted as a consequence of a triggered star formation process. Additionally, in the specific case of NGC 6193, an indication of possible non-coeval star formation was found.
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Search Results
- 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.
- 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/A+A/592/A20
- Title:
- NGC 1316 and NGC 612 WISE images
- Short Name:
- J/A+A/592/A20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most radio galaxies are hosted by giant gas-poor ellipticals, but some contain significant amounts of dust, which is likely to be of external origin. In order to characterize the mid-IR properties of two of the most nearby and brightest merger-remnant radio galaxies of the Southern hemisphere, NGC 1316 (Fornax A) and NGC 612 (PKS 0131-36), we used observations with the Wide-field Infrared Survey Explorer (WISE) at wavelengths of 3.4, 4.6, 12 and 22 micron and Spitzer mid-infrared spectra. By applying a resolution-enhancement technique, new WISE images were produced at angular resolutions ranging from 2.6" to 5.5". Global measurements were performed in the four WISE bands, and stellar masses and star-formation rates were estimated using published scaling relations. Two methods were used to uncover the distribution of dust, one relying on two-dimensional fits to the 3.4 micron images to model the starlight, and the other one using a simple scaling and subtraction of the 3.4 micron images to estimate the stellar continuum contribution to the emission in the 12 and 22 micron bands. The two galaxies differ markedly in their mid-IR properties. The 3.4 micron brightness distribution can be well represented by the superposition of two Sersic models in NGC 1316 and by a Sersic model and an exponential disk in NGC 612. The WISE colors of NGC 1316 are typical of those of early-type galaxies; those of NGC 612 are in the range found for star-forming galaxies. From the 22 micron luminosity, we infer a star-formation rate of about 0.7 solar masses per year in NGC 1316 and about 7 solar masses per year in NGC 612. Spitzer spectroscopy shows that the 7.7-to-11.3 micron PAH line ratio is significantly lower in NGC 1316 than in NGC 612. The WISE images reveal resolved emission from dust in the central 1'-2' of the galaxies. In NGC 1316, the extra-nuclear emission coincides with two dusty regions NW and SE of the nucleus seen in extinction in optical images and where molecular gas is known to reside. In NGC 612 it comes from a warped disk. This suggests a recent infall onto NGC 1316 and disruption of one or several smaller gas-rich galaxies, but a smoother accretion in NGC 612. While the nucleus of NGC 1316 is currently dormant and the galaxy is likely to evolve into a passive elliptical, NGC 612 has the potential of growing a larger disk and sustaining an active nucleus. NGC 1316 and NGC 612 represent interesting challenges to models of formation and evolution of galaxies and AGNs.
- 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/A+AS/127/471
- Title:
- NGC 6380 and Terzan 12 VI photometry
- Short Name:
- J/A+AS/127/471
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present V, I photometry of the bulge globular clusters NGC 6380 and Terzan 12, using the ESO NTT telescope. For the first time colour-magnitude diagrams are obtained for these clusters, allowing us to derive reliable cluster parameters. From the colour-magnitude diagram morphology both clusters result to be metal-rich. For NGC 6380 we estimate [Fe/H]~-0.5, a reddening of E(B-V)=1.07 and a distance of d~9.8 kpc. For Terzan 12 we obtain [Fe/H]~-0.5, E(B-V)=2.06 and d~3.4kpc.
- 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/A+A/554/A128
- Title:
- NGC 6824 and UGC 11919 data cubes
- Short Name:
- J/A+A/554/A128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the results of a mass decomposition of two spiral galaxies, NGC 6824 and UGC 11919. In a previous analysis of the Hyperleda catalog, the galaxies were identified as having a peculiar dynamical mass-to-light ratio. The aim of this study is to confirm or disprove the preliminary findings, indicating a non-standard stellar initial mass function (IMF) for the galaxies. The surface photometry in B,V, and R bands was carried out with the Apache Point 0.5-m telescope and the HI data cubes were obtained with the Westerbork Synthesis Radio Telescope (WSRT). Photometric profiles were decomposed into bulge and exponential disk components.
- 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.
