- 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.
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- ID:
- ivo://CDS.VizieR/J/AJ/100/1811
- Title:
- UBV photometry in Ruprecht 106
- Short Name:
- J/AJ/100/1811
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBV CCD photometry for about 2500 stars in the Galactic globular cluster Ruprecht 106 has been performed yielding the first color-magnitude diagram (CMD) for this object. The CMD extends down to about 2 mag fainter than the main-sequence turnoff (TO). The cluster possesses a remarkably flat horizontal branch which lies completely to the red of the instability strip. From the analysis of the CMD the following basic parameters have been determined: [Fe/H] = -1.09 and primordial helium abundance Yp = 0.20 0.05. A sizable, highly centrally concentrated population of blue stragglers has also been detected. The location and morphology of the mean ridge lines in the CMD of Ruprecht 106 have then been differentially compared with that of the metal-rich cluster 47 Tuc, NGC 362, a cluster of intermediate metallicity, and with two well-studied metal-poor clusters, M68 and NGC 6397. Significant differences in the positions of the TOs are apparent in the comparison with the metal-poor clusters. These differences can be explained if Ruprecht 106 is 4-5 Gyr younger than NGC 6397 and M68, although alternative, less straightforward explanations cannot be ruled out. The horizontal branch morphology fits perfectly into this picture using models with non-solar-scaled abundances ([O/Fe]>0.5), showing that two second parameters are at work in this cluster, i.e., age (the dominant) and O enhancement. If these findings are confirmed, Ruprecht 106 will turn out to be the first young metal-poor Galactic globular cluster discovered, with quite strong implications for the study of the collapse and enrichment of the Galactic halo.
- ID:
- ivo://CDS.VizieR/J/AJ/112/2020
- Title:
- UBV Photometry of globular cluster NGC1841
- Short Name:
- J/AJ/112/2020
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The observations were acquired in two nights, 1993 December 20-22, with the EMMI camera on the NTT telescope at ESO. The photometric limit is close to the cluster main-sequence turnoff; a comparison of the photometry with Walker (1990AJ....100.1532W) shows slight systematic differences . the present magnitudes being fainter by 0.03-0.05mag, and colors being bluer by 0.05mag. The estimated parameters of the populous globular cluster NGC 1841, located approximately 15deg from each of the Magellanic Clouds and probably dynamically associated with the LMC, are: [Fe/H] = -2.0 +/- 0.15 E(B-V) = 0.17 +/- 0.03 mag (m-M)_0_ = 18.26 +/- 0.11 mag (true distance modulus)
- 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/A+AS/111/75
- Title:
- UBVRI CCD photometry of NGC 4755
- Short Name:
- J/A+AS/111/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD observations in U, B, V, R and I passbands have been used to generate (U-B), (B-V) colour-colour and deep V, (B-V); V, (U-B) and V, (V-I) colour-magnitude diagrams for the young open cluster NGC 4755. The sample consists of 813 stars reaching down to V about 20mag.
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/145/7
- Title:
- UBVRI CCD photometry of the open cluster NGC 6811
- Short Name:
- J/AJ/145/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 6811 is one of the four open clusters located in the Kepler spacecraft field of view. We obtained UBVRI photometry of the cluster on six nights (four of them photometric) with the 1.08m Hall and 1.83m Perkins telescopes at Lowell Observatory. The mean photometric precision ranges from better than 0.01mag in the V, B-V, V-R, and V-I indices among stars brighter than magnitude 15 to about 0.05mag for U-B at magnitude 18. We followed a Bayesian statistical approach using the Markov Chain Monte Carlo algorithm to determine the cluster reddening, distance, age, and iron content from a maximum-likelihood fit to stellar isochrones. Using the Yale-Yonsei isochrones, we derived E(B-V)=0.066+/-0.025, (m-M)_V_=10.13+/-0.19, age=1.06+/-0.19Gyr, and Z=0.012+/-0.004 ([Fe/H]=-0.18); with the Padova isochrones, we found E(B-V)=0.081+/-0.015, (m-M)_V_=10.31+/-0.11, age=0.94+/-0.08Gyr, and Z=0.012+/-0.002 ([Fe/H]=-0.20). The uncertainties include possible errors in the photometric zero points of +/-0.01mag, but do not include uncertainties in the models. Taking into account the differences between the two sets of models, we find the best estimate for the cluster parameters to be E(B-V)=0.074+/-0.024, (m-M)_V_=10.22+/-0.18, age=1.00+/-0.17Gyr, and Z=0.012+/-0.004 ([Fe/H]=-0.19).
