- ID:
- ivo://CDS.VizieR/J/A+A/381/884
- Title:
- UBVI CCD photometry in NGC 2571
- Short Name:
- J/A+A/381/884
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD UBVI imaging photometry was carried out in the field of the open cluster NGC 2571. From the analysis of our data we state the cluster is at a distance of 1380+/-130pc and its age is 50+/-10x10^6yr. The cluster mass function has a slope larger than a typical Salpeter's law. There are two notorious features in NGC 2571: the cluster contains a high proportion of stars located below the reference line that are serious candidates to be metallic line stars (probably Am-Fm), and shows also a sharp gap along its main sequence that cannot be explained by a random process nor by a biased rejection of cluster members. A striking blue object was detected in the cluster field that could be a white dwarf candidate. We carried out CCD imaging photometry in the Kron-Cousins UBVI system on April 27 and 29, 1994 using a 1024x1024pix CCD with a scale of 0.37"/pix and a field of view of 6.3'x6.3' attached to the 1.54-m Danish telescope at ESO, La Silla, Chile.
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- ID:
- ivo://CDS.VizieR/J/A+A/592/A149
- Title:
- UBVI CCD photometry of Carina region stars
- Short Name:
- J/A+A/592/A149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Previous studies of the Carina region have revealed its complexity and richness as well as a significant number of early-type stars. However, in many cases, these studies only concentrated on the central region (Trumpler 14/16) or were not homogeneous. This latter aspect, in particular is crucial because very different ages and distances for key clusters have been claimed in recent years. The aim of this work is to study in detail an area of the Galactic plane in Carina, east ward Carina. We analyze the properties of different stellar populations and focus on a sample of open clusters and their population of young stellar objects and highly reddened early stars. We also studied the stellar mass distribution in these clusters and the possible scenario of their formation. Finally, we outline the Galactic spiral structure in this direction. We obtained deep and homogeneous photometric data (UBVIKC) for six young open clusters: NGC 3752, Trumpler 18, NGC 3590, Hogg 10, 11, and 12, located in Carina at l~291, and their adjacent stellar fields, which we complemented with spectroscopic observations of a few selected targets. We also culled additional information from the literature, which includes stellar spectral classifications and near-infrared photometry from 2MASS. We finally developed a numerical code that allowed us to perform a homogeneous and systematic analysis of the data. Our results provide more reliable estimates of distances, color excesses, masses, and ages of the stellar populations in this direction. We estimate the basic parameters of the studied clusters and find that they identify two overdensities of young stellar populations located at about 1.8kpc and 2.8kpc, with E_(B-V)_~0.1-0.6. We find evidence of pre-main-sequence populations inside them, with an apparent coeval stellar formation in the most conspicuous clusters. We also discuss apparent age and distance gradients in the direction NW-SE. We study the mass distributions of the covered clusters and several others in the region (which we took form the literature). They consistently show a canonical IMF slope (the Salpeter one). We discover and characterise an abnormally reddened massive stellar population, scattered between 6.6 and 11kpc. Spectroscopic observations of ten stars of this latter population show that all selected targets were massive OB stars. Their location is consistent with the position of the Carina-Sagittarius spiral arm.
- ID:
- ivo://CDS.VizieR/J/MNRAS/341/805
- Title:
- UBVI CCD photometry of Cep OB3b
- Short Name:
- J/MNRAS/341/805
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a low-mass pre-main-sequence (PMS) stellar population in the younger subgroup of the Cepheus OB3 association, Cep OB3b, using UBVI CCD photometry and follow-up spectroscopy. The optical survey covers approximately 1300arcmin^2^ on the sky and gives a global photometric and astrometric catalogue for more than 7000 objects. The location of a PMS population is well defined in a V versus (V-I) colour-magnitude diagram.
- ID:
- ivo://CDS.VizieR/J/MNRAS/310/982
- Title:
- UBVI CCD Photometry of M11 - II.
- Short Name:
- J/MNRAS/310/982
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This directory contains Johnson-Cousins UBVI photometric data for M11 (NGC 6705) and a neighboring field (around PN G027.4-03.5). The photometric data for M11 are tightly matched to the SAAO E-region standard system (Menzies et al. SAAO Circ., 1989SAAOC..13....1M; Menzies et al., 1991MNRAS.248..642M; Kilkenny et al., 1998MNRAS.294...93K). For the PN G027.4-03.5 region, the standard system of Landolt (1992, Cat. <II/183>) was used and small systematic difference in photometry between the two tables may be present, in particular in (U-B). Table 2 contains UBVI data for 14,179 stars brighter than V=17mag in M11 (about 40arcmin x 40arcmin region). The star numbers and proper motion memberships by McNamara et al. (1977A&AS...27..117M) and Su et al. (1998, Cat. <J/A+AS/128/255>) are also identified and included. Table 3 contains UBVI data for 3,676 stars around PN G027.4-03.5.
- ID:
- ivo://CDS.VizieR/J/MNRAS/306/361
- Title:
- UBVI CCD photometry of M35 (NGC 2168)
- Short Name:
- J/MNRAS/306/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVI CCD photometry has been obtained for the intermediate-age open cluster M35 (NGC 2168). From this new photometry we derived the cluster parameters (Vo-MV= 9.60+/-0.10 mag, E(B-V) = 0.255+/-0.024 mag), age (logAge=8.3+/-0.3) and a photometric abundance (Z~0.008, i.e. [Fe/H]~-0.3) from comparison with theoretical isochrones of the Padova group. A minimum binary frequency (35+/-5%) was estimated from the distribution of distance moduli of unevolved proper motion members. Faint photometric members were selected by using differences in the reddening effect on colour indices.
- ID:
- ivo://CDS.VizieR/J/AJ/123/290
- Title:
- UBVI CCD photometry of NGC 2516
- Short Name:
- J/AJ/123/290
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBVI CCD photometry of the intermediate-age open cluster NGC 2516.
- ID:
- ivo://CDS.VizieR/J/AJ/145/46
- Title:
- UBVIc photometry in Westerlund 1
- Short Name:
- J/AJ/145/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Westerlund 1 is the most important starburst cluster in the Galaxy due to its massive star content. We have performed BVI_C_ and JK_S_ photometry to investigate the initial mass function (IMF). By comparing the observed color with the spectral-type-intrinsic-color relation, we obtain the mean interstellar reddening of <E(B-V)>=4.19+/-0.23 and <E(J-K_S_)>=1.70+/-0.21. Due to the heavy extinction toward the cluster, the zero-age main sequence fitting method based on optical photometry proved to be inappropriate for the distance determination, while the near-infrared photometry gave a reliable distance to the cluster, 3.8kpc from the empirical relation. Using the recent theoretical stellar evolution models with rotation, the age of the cluster is estimated to be 5.0+/-1.0Myr. We derived the IMF in the massive part and obtained a fairly shallow slope of {Gamma}=-0.8+/-0.1. The integration of the IMF gave a total mass for the cluster in excess of 5.0x10^4^M_{sun}_. The IMF shows a clear radial variation indicating the presence of mass segregation. We also discuss the possible star formation history of Westerlund 1 from the presence of red supergiants and relatively low luminosity yellow hypergiants.
- ID:
- ivo://CDS.VizieR/J/MNRAS/383/1241
- Title:
- UBVIc photometry of cluster Berkeley 59
- Short Name:
- J/MNRAS/383/1241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBVIc CCD photometry of the young open cluster Be 59 with the aim to study the star formation scenario in the cluster. The radial extent of the cluster is found to be ~10arcmin (2.9pc). The interstellar extinction in the cluster region varies between E(B-V)=1.4 to 1.8mag. The ratio of total-to-selective extinction in the cluster region is estimated as 3.7+/-0.3. The distance of the cluster is found to be 1.00+/-0.05kpc. Using near-infrared (NIR) colours and slitless spectroscopy, we have identified young stellar objects (YSOs) in the open cluster Be 59 region. The Midcourse Space Experiment (MSX) and IRAS-HIRES images around the cluster region are also used to study the emission from unidentified infrared bands and to estimate the spatial distribution of optical depth of warm and cold interstellar dust.
- ID:
- ivo://CDS.VizieR/J/A+A/436/527
- Title:
- UBVIc photometry of NGC 4852
- Short Name:
- J/A+A/436/527
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present wide-field deep UBVIc photometry for the previously unstudied open cluster NGC 4852 down to a limiting magnitude Ic~24, obtained from observations taken with the Wide Field Imager camera on-board the MPG/ESO 2.2m telescope at La Silla (ESO, Chile), in the photometric night of July 7, 2002. These data are used to obtain the first estimate of the cluster basic parameters, to study the cluster spatial extension by means of star counts, and to derive the Luminosity (LF) and Mass Functions (MF). The cluster radius turns out to be 5.0+/-1.0arcmin. The cluster emerges clearly from the field down to V=20mag. At fainter magnitudes, it is completely confused with the general Galactic disk field. The stars inside this region define a young open cluster (200 million years old) 1.1kpc far from the Sun (m-M=11.60, E(B-V)=0.45). The Present Day Mass Functions (PDMF) from the V photometry is one of the most extended in mass obtained to date, and can be represented as a power-law with a slope alpha=2.3+/-0.3 and (the Salpeter MF in this notation has a slope alpha=2.35), in the mass range 3.2<=m/m_{sun}_<=0.6. Below this mass, the MF cannot be considered as representative of the cluster MF, as the cluster merges with the field and therefore the MF is the result of the combined effect of strong irregularities in the stellar background and interaction of the cluster with the dense Galactic field. The cluster total mass at the limiting magnitude results to be 2570+/-210M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/A+A/419/149
- Title:
- UBV(I)c photometry of NGC 6996
- Short Name:
- J/A+A/419/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and discuss broad band CCD UBV(I)c photometry and low resolution spectroscopy for stars in the region of the open cluster NGC 6996, located in the North America Nebula. The new data allow us to tightly constrain the basic properties of this object. We revise the cluster size, which in the past has been significantly underestimated. The width of the Main Sequence is mainly interpreted in terms of differential reddening, and indeed the stars' color excess E(B-V) ranges from 0.43 to 0.65, implying the presence of a significant and evenly distributed dust component. We cross-correlate our optical photometry with near infrared photometry from 2MASS, and by means of spectral classification we are able to build extinction curves for an handful of bright members. We find that the reddening slope and the total to selective absorption ratio Rv toward NGC 6996 are anomalous. Moreover the reddening-corrected colors and magnitudes allow us to derive estimates for the cluster distance and age, which turn out to be 760+/-70pc (V0-MV=9.4+/-0.2) and ~350Myr, respectively. Based on our results, we suggest that NGC 6996 is located in front of the North America Nebula, and does not seem to have any apparent relationship with it.
