- ID:
- ivo://CDS.VizieR/J/MNRAS/408/1147
- Title:
- UBVI photometry of 4 open clusters
- Short Name:
- J/MNRAS/408/1147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD photometry in the Johnson UBV and Kron-Cousins I systems down to V~22.0 for the open clusters NGC 2311, Trumpler 6, NGC 2432 and BH 54 and their surrounding fields. Trumpler 6 and BH 54 have never been studied before and so we provide, for the first time, estimates of their fundamental parameters. We obtained colour-magnitude diagrams (CMDs) and colour-colour diagrams cleaned from field star contamination by statistically subtracting stars in terms of spatial density, magnitude and colour distributions. Cluster angular radii were estimated from star counts in appropriate-sized boxes distributed throughout the entire observed fields. Using the cleaned CMDs and colour-colour diagrams, we applied sound photometric membership criteria to discriminate cluster members from interloper field stars. The interstellar extinction across the cluster fields derived from the 100-{mu}m dust emission full-sky maps can be considered uniform within the quoted uncertainties. The E(B-V) and E(V-I) colour excesses and the apparent distance moduli of the clusters were estimated from the fit of the zero-age main-sequence to the colour-colour diagrams and CMDs, respectively. Cluster ages were determined from the comparison of the four clusters' CMDs with solar metallicity theoretical isochrones of the Geneva group. All the clusters were found to be moderately young objects, their ages ranging between 60 and 250Myr.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/402/2720
- Title:
- UBVI photometry of 5 open clusters
- Short Name:
- J/MNRAS/402/2720
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained CCD UBVI_KC_ photometry down to V~21.0 for the open clusters Berkeley 26, Czernik 27, Melotte 72, NGC 2479 and BH 37. The latter has never been studied before. Cluster stellar density profiles were obtained from star counts in appropriate-sized boxes distributed throughout the entire observed fields. Based on different measured indices, we estimate the ages of Berkeley 26, Melotte 72 and NGC 2479. On the other hand, we indicate possible solutions for the cluster fundamental parameters by matching theoretical isochrones which reasonably reproduce the main cluster features in their colour-magnitude diagrams. In the case of NGC 2479, the cluster E(BV) and E(VI) colour excesses and apparent distance modulus were estimated from the fit of the zero-age main sequence to the colour-colour and colour-magnitude diagrams, respectively.
- ID:
- ivo://CDS.VizieR/J/MNRAS/428/502
- Title:
- UBVI photometry of 7 open clusters
- Short Name:
- J/MNRAS/428/502
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New photometric material is presented for six outer disc supposedly old, Galactic star clusters: Berkeley 76, Haffner 4, Ruprecht 10, Haffner 7, Haffner 11 and Haffner 15, which are projected against the rich and complex Canis Major overdensity at 225{deg}<=l<=248{deg}, -7{deg}b<=-2{deg}. This CCD data set, in the UBVI passbands, is used to derive their fundamental parameters, in particular age and distance. Four of the program clusters turn out to be older than 1Gyr. This fact makes them ideal targets for future spectroscopic campaigns aiming at deriving their metal abundances. This, in turn, contributes to increase the number of well-studied outer disc old open clusters. Only Haffner 15, previously considered an old cluster, is found to be a young, significantly reddened cluster, member of the Perseus arm in the third Galactic quadrant. As for Haffner 4, we suggest an age of about half a Gyr. The most interesting result we found is that Berkeley 76 is probably located at more than 17kpc from the Galactic centre, and therefore is among the most peripherical old open clusters so far detected. Besides, for Ruprecht 10 and Haffner 7, which were never studied before, we propose ages larger than 1Gyr. All the old clusters of this sample are scarcely populated and show evidence of tidal interaction with the Milky Way, and are therefore most probably in advanced stages of dynamical dissolution.
- ID:
- ivo://CDS.VizieR/J/A+A/536/A101
- Title:
- UBVI photometry towards (l=314,b=0)
- Short Name:
- J/A+A/536/A101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spiral structure of the Milky Way is nowadays receiving renewed attention thanks to the combined efforts of observational campaigns in different wavelength regimes, from the optical to the radio. We start in the paper the exploration of a number of key sectors (line of sights) in the inner Milky Way, where the spiral structure is still poorly known. We search for density enhancements of young stars that might plausibly be associated with spiral structure. To this aim we collect sufficiently wide-field UBVI photometry to allow us to probe in statistical sense the distribution in reddening and distance of young stars in the field. The intensive usage of U-band photometry - although heavily demanding in terms of observational efforts - ensures robust determination of reddening and hence distance for stars of spectral type earlier than A0, which are well-known spiral arm tracers, even though no spectroscopic information are available. The fields we use are large enough to include in most cases well-studied Galactic clusters, which we use as bench-marks to assess the quality and standardisation of the data, and to validate our method. We focus in this paper on the line of sight to the Galactic longitude l=314{deg}, where previous surveys already detected H{alpha} emitters at different standard of rest velocities, and hence distances. The difficulty, however, to translate velocity into distance make predictions on the spiral structure quite vague. First of all, we made exhaustive tests to show that our data-set is in the standard system, and calibrated our method using the two open clusters NGC 5617 and Pismis 19 which happen to be in the field, and for which we found estimates of the basic parameters in full agreement with the literature. We then applied the method to the general field stars and detected signatures of three different groups of stars, evenly distributed across the field of view, at 1.5^+0.5^_-0.2_, 2.5^+0.3^_-0.5_, and 5.1^+1.5^_-1.1_kpc, respectively. These distances are compatible with the location of the nowadays commonly accepted description of the Carina-Sagittarius and Scutum-Crux arms, at heliocentric distance of ~2 an 5kpc, respectively. As a consequence, we consider these groups to be good candidates to trace the location of these two inner arms. In line with previous studies, this investigation demonstrates once again how powerful the use of U-band photometry is to characterize ensembles of young stars, and make predictions on the spiral structure of the Milky Way.
- ID:
- ivo://CDS.VizieR/J/ApJS/93/187
- Title:
- UBV Photometry in NGC 7419
- Short Name:
- J/ApJS/93/187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBV CCD photometry has been carried out on the heavily reddened (A_V_=6.7) Cepheus open cluster NGC 7419. An age of 14+/-2 Myr and a distance of 2.3kpc have been derived using the isochrones of Maeder. The mass function of the cluster satisfies the Salpeter from n(M)~M^-{gamma}^ with {gamma}=2.25. The cluster is dynamically relaxed.
- ID:
- ivo://CDS.VizieR/II/232
- Title:
- UBV photometry of selected regions in the MCs
- Short Name:
- II/232
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue groups broad-band CCD photometry made in 8 regions of the Magellanic Clouds which were used for the study of stellar populations in the Magellanic Clouds. The photometry yielded 293693 BV entries with 136155 having additional U information, published or to be published in 4 different papers.
- ID:
- ivo://CDS.VizieR/J/A+A/493/71
- Title:
- UBV photometry of Shorlin 1
- Short Name:
- J/A+A/493/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detailed spiral structure of the outer Galactic disk remains poorly constrained, and for several line of sights in the Galaxy we depend on model extrapolations. One of these regions is the fourth Galactic quadrant, between Vela and Carina (270{deg}<=l<=300{deg}), where, apart from the conspicuous Carina branch of the Carina Sagittarius arm, no spiral arms have been detected so far in the optical beyond l~270{deg}. By means of deep UBVI photometry, we search for spiral features in known low absorption windows. Although observationally demanding, U photometry constitutes a powerful tool for detecting and characterizing distant aggregates of young stars, and allows firmer distance estimates to be derived. We study a direction close to the tangent (l~290{deg}) of the Carina arm, in an attempt to detect optical spiral tracers far beyond the Carina branch, where radio observations and model predictions appear to indicate the presence of an extension of the Perseus and Norma-Cygnus spiral arms in the fourth quadrant. Along this line of sight, we detect three distinct groups of young stars. Two of them, at distances of ~2.5 and ~6.0kpc, belong to the Carina spiral arm, which is traversed twice in this particular direction. Interestingly, the latter is detected for the first time. The third group, at a distance of ~12.7kpc, is probably related to the Perseus arm which lies beyond the Carina arm, and constitutes the first optical detection of this arm in the fourth Galactic quadrant. The position of this feature is consistent with both HI observations and model predictions. We also present evidence that this extremely distant group, formerly assumed to be a star cluster (Shorlin 1), is a diffuse, young population, typically found in spiral galaxies. In addition, our data-set does not support, as claimed in the literature, the possible presence of the Monoceros Ring in this direction. This study highlights how multicolor optical studies can be effective in probing the spiral structure of the outer Galactic disk. More fields need to be studied in this region of the Galaxy to constrain the spiral structure in the fourth Galactic quadrant more accurately, in particular, the shape and extent of the Perseus arm, and, possibly, to detect the even more distant Norma-Cygnus arm.
- ID:
- ivo://CDS.VizieR/II/236
- Title:
- UBVR CCD survey of the Magellanic clouds
- Short Name:
- II/236
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry and a preliminary interpretation of a UBVR survey of the Large and Small Magellanic Clouds, which covers 14.5 deg^2^ and 7.2deg^2^, respectively. This study is aimed at obtaining well-calibrated data on the brighter, massive stars, complementing recent, deeper CCD surveys. Our catalog contains 179,655 LMC and 84,995 SMC stars brighter than V~18.0, and is photometrically complete to U~B~V~15.7 and R~15.2, although stars in crowded regions are selectively missed. We compare our photometry to that of others, and describe the need for gravity-dependent corrections to our CCD U-band photometry. We provide a preliminary cross-reference between our catalog stars and the stars with existing spectroscopy.
- ID:
- ivo://CDS.VizieR/J/AJ/118/2894
- Title:
- UBVRI CCD photometry in NGC 188
- Short Name:
- J/AJ/118/2894
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-precision UBVRI CCD photometry of the old open cluster NGC 188. Our color-magnitude diagram extends from near the red giant branch tip to as faint as ~5mag below the main-sequence turnoff. From an analysis of these data along with published photometry for M67, we draw the following conclusions: (1) From the UBV two-color diagram, we find a reddening of E(B-V)=0.04+/-0.02 for M67 and E(B-V)=0.09+/-0.02 for NGC 188. (2) Based on main-sequence fitting to solar abundance isochrones, the distance moduli turn out to be (m-M)v=9.69+/-0.11 for M67 and (m-M)v=11.44+/-0.08 for NGC 188. (3) The comparison of the CMDs to theoretical isochrones indicates that an amount of core convective overshoot equivalent to 0.10 of a pressure scale height is appropriate for M67, while no overshoot is required to fit the CMD of NGC 188. These isochrones suggest that NGC 188 is 3.0+/-0.7 Gyr older than M67. (4) There is a clear indication of mass segregation in both M67 and NGC 188, with the most massive stars (M/M_{sun}_>1.1) being more centrally concentrated than those that are the least massive (0.8>=M/M_{sun}_>0.65).
- ID:
- ivo://CDS.VizieR/J/AJ/147/139
- Title:
- UBVRI CCD photometry of open clusters. II. NGC 6866
- Short Name:
- J/AJ/147/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have developed a maximum-likelihood procedure to fit theoretical isochrones to the observed cluster color-magnitude diagrams of NGC6866, an open cluster in the Kepler spacecraft field of view. The Markov chain Monte Carlo algorithm permits exploration of the entire parameter space of a set of isochrones to find both the best solution and the statistical uncertainties. For clusters in the age range of NGC6866 with few, if any, red giant members, a purely photometric determination of the cluster properties is not well-constrained. Nevertheless, based on our UBVRI photometry alone, we have derived the distance, reddening, age, and metallicity of the cluster and established estimates for the binary nature and membership probability of individual stars. We derive the following values for the cluster properties: (m-M)_V_=10.98+/-0.24, E(B-V)=0.16+/-0.04 (so the distance=1250pc), age=705+/-170Myr, and Z=0.014+/-0.005.
