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121. BVI photometry of the SMC star cluster ESO 51-SC09
ID:
ivo://CDS.VizieR/J/ApJ/756/L32
Title:
BVI photometry of the SMC star cluster ESO 51-SC09
Short Name:
J/ApJ/756/L32
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results on the age and metallicity estimates of the astonishingly unstudied Small Magellanic Cloud (SMC) cluster (ESO 51-SC09), from CCD BVI photometry obtained at the ESO NTT with the EMMI attached. ESO 51-SC09 turns out to be a relatively small cluster (FWHM=10+/-1pc) located ~4{deg} northward from the galaxy center. We report for the first time a mean cluster age of 7.0+/-1.3Gyr and a mean cluster metallicity of [Fe/H]=-1.00+/-0.15 dex, concluding that ESO 51-SC09 belongs to the group of the oldest SMC clusters. We found that the cluster is projected onto an older (age~10-13Gyr) and more metal-poor ([Fe/H]=-1.3+/-0.2 dex) dominant field stellar population, so that the cluster could have reached its current location because of its orbital motion.
122. BVI photometry of two open clusters
ID:
ivo://CDS.VizieR/J/A+A/388/179
Title:
BVI photometry of two open clusters
Short Name:
J/A+A/388/179
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of CCD BVI Johnson-Cousins photometry down to V~19mag in the regions of the unstudied stellar groups Pismis 23 and BH 222, both projected close to the direction towards the Galactic centre. We measured V magnitude and B-V and V-I colours for a total of 928 stars in fields of about 4'x4'.
123. BVI photometry of 4 young open clusters
ID:
ivo://CDS.VizieR/J/A+A/360/529
Title:
BVI photometry of 4 young open clusters
Short Name:
J/A+A/360/529
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present CCD observations in the B, V, and I passbands obtained for stars in the fields of the open clusters Pismis 22, NGC 6178, NGC 6216, and Ruprecht 130, projected not far from the Galactic centre (|l|<30{deg}, |b|<2{deg}). The sample consists of about 790 stars reaching down to V~18-19mag. From the analysis of the colour magnitude diagrams, we confirmed the physical reality of the clusters and derived their reddening, distance and age. In addition, we obtained flux-calibrated integrated spectra in the range 3500-9200{AA} for the cluster sample. The equivalent widths of the Balmer lines provided us with age estimates, while the comparison with template spectra allowed us to derive both foreground reddening and age. The photometric and spectroscopic results reveal that the four studied objects are young open clusters with ages ranging between 35 and 50Myr. The clusters, located between 1.0kpc and 4.3kpc from the Sun, are affected by different amounts of interstellar visual absorption (0.6=~A_v_=~6.0).
124. BVI photometry of young stars in 10 clusters
ID:
ivo://CDS.VizieR/J/MNRAS/375/1220
Title:
BVI photometry of young stars in 10 clusters
Short Name:
J/MNRAS/375/1220
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have selected pre-main-sequence (PMS) stars in 12 groups of notional ages ranging from 1 to 35Myr, using heterogeneous membership criteria. Using these members we have constructed empirical isochrones in V, V-I colour-magnitude diagrams. This allows us to identify clearly the gap between the radiative main sequence and the convective PMS (the RC gap). We follow the evolution of this gap with age and show that it can be a useful age indicator for groups less than =15 Myr old. We also observe a reduction in absolute spreads about the sequences with age. Finally, the empirical isochrones allow us to place the groups in order of age, independently of theory. The youngest groups can be collated into three sets of similar ages. The youngest set is the ONC, NGC 6530 and IC 5146 (nominally 1Myr); next Cep OB3b, NGC 2362, Ori and NGC 2264 (nominally 3Myr); and finally Ori and IC 348 (nominally 45Myr). This suggests Cep OB3b is younger than previously thought, and IC 348 older. For IC 348 the stellar rotation rate distribution and fraction of stars with discs imply a younger age than we derive. We suggest this is because of the absence of O-stars in this cluster, whose winds and/or ionizing radiation may be an important factor in the removal of discs in other clusters.
125. BVJH photometry of Andrews-Lindsay 1 field
ID:
ivo://CDS.VizieR/J/A+A/567/A1
Title:
BVJH photometry of Andrews-Lindsay 1 field
Short Name:
J/A+A/567/A1
Date:
21 Oct 2021
Publisher:
CDS
Description:
Andrews-Lindsay 1 is a pertinent open cluster because it may host the planetary nebula (PN) PHR 1315-6555, yet ambiguities linger concerning its fundamental parameters (>50% scatter). New multiband BVJHW_1-4_ photometry for cluster and field stars, in concert with observations of recently discovered classical Cepheids, were used to constrain the reddening and velocity-distance profiles along the sightline. That analysis yielded the following parameters for the cluster: E(J-H)=0.24+/-0.03, d=10.0+/-0.4kpc (d_JH_=9.9+/-0.6kpc, d_BV_=10.1+/-0.5kpc), and log{tau}=8.90+/-0.15. The steep velocity-distance gradient along l~305{deg} indicates that two remote objects sharing spatial and kinematic parameters (i.e., PHR 1315-6555 and Andrews-Lindsay 1) are associated, thus confirming claims that the PN is a cluster member. The new distance for PHR 1315-6555 is among the most precise established yet for a Galactic PN ({sigma}/d=4%).
126. BV photometry and Li abundances in NGC3960
ID:
ivo://CDS.VizieR/J/A+A/475/539
Title:
BV photometry and Li abundances in NGC3960
Short Name:
J/A+A/475/539
Date:
21 Oct 2021
Publisher:
CDS
Description:
Old open clusters are very useful targets to investigate mechanisms responsible for lithium (Li) depletion during the main sequence. Comparison of the Li abundances in clusters of different age allows us to understand the efficiency of the Li destruction process. To determine the membership and Li abundance in a sample of candidate members of the open cluster NGC 3960 (age ~1Gyr), aiming to fill the gap between 0.6 and 2Gyr in the empirical description of the behavior of the average Li abundance as a function of the stellar age. We use VLT/FLAMES Giraffe spectra to determine the radial velocities and thus the membership of a sample of 113 photometrically selected candidate cluster members. From the analysis of the Li line we derive Li abundances for both cluster members and non-members. 39 stars have radial velocities consistent with membership, with an expected fraction of contaminating field stars of about 20%. Li is detected in 29 of the radial velocity members; we consider these stars as cluster members, while we make the reasonable assumption that the remaining 10 radial velocity members without Li are among the contaminating stars. Li abundances of the stars hotter than about 6000K are similar to those of stars in the Hyades, while they are slightly smaller for cooler stars. This confirms that NGC 3960 is older than the Hyades. The average Li abundance of stars cooler than about 6000K indicates that the Li Pop. I plateau might start at ~1Gyr, rather than 2Gyr, which is the upper limit previously derived in the literature. We also find that the fraction of field stars with high Li abundance (>1.5) is about one third of the whole sample, which is in agreement with previous estimates. The fraction of contaminating field stars is consistent with that previously derived by us from photometry.
127. BV photometry of Blanco 1 stars
ID:
ivo://CDS.VizieR/J/A+AS/121/213
Title:
BV photometry of Blanco 1 stars
Short Name:
J/A+AS/121/213
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of H{alpha}(6562A) and Li I(6708A) observations of 114 low-mass stars of the young open cluster Blanco 1. We also present observations of 30 stars in Ca II(K). This work extends the first Blanco 1 spectroscopic study of Panagi et al. (1994A&A...285..233D). From a sample of four well-studied clusters, including Blanco 1, we find that the fraction of H{alpha} emission-line stars amongst K dwarfs is a good indicator of relative age, with a smaller fraction indicative of older age. Blanco 1 shows a relatively small fraction of emitters, inconsistent with previous age estimates for the cluster. We estimate the cluster age to to be 90+/-25Myr, slightly older than the Pleiades. The method is shown to be more sensitive to age than lithium and a useful alternative to other age measurement techniques. The variation of H{alpha} with (B-V) is similar to that observed in the older solar neighbourhood dwarfs, suggesting that, at least for the absorption-line stars, the contribution of stellar rotation to the equivalent width is unclear. We combine both spectroscopy and photometry to revise cluster membership and give accurate positions for all these stars.
128. BV photometry of Bochum 7 members
ID:
ivo://CDS.VizieR/J/A+A/616/A40
Title:
BV photometry of Bochum 7 members
Short Name:
J/A+A/616/A40
Date:
21 Oct 2021
Publisher:
CDS
Description:
We plan to identify the members of the Bochum 7 association by performing simultaneous astrometric and spectrophotometric analyses, and estimate its distance and evolutionary stage. We used our own visual spectroscopic and UBV photometric data of a 30{deg}x30{deg} region centered at RA=8:44:47.2, DE=-45:58:55.5. This information enabled us to estimate the spectral classification and distance of all stars present in the region. The proper motion was analyzed with data of the UCAC 5 catalog and was used to identify the members of this association. We added JHK data from 2MASS and IRAS catalogs to check for the presence of infrared (IR) excess stars. We found that Bochum 7 is an OB association with at least 27 identified stellar members (l=265.12{deg}, b=-2{deg}) at a distance of ~=5640pc. Its proper motion is pm_RA_cosDE=-4.92+/-0.08mas/yr, pm_DE_=3.26+/-0.08mas/yr. We derived an average heliocentric radial velocity of ~35km/s and were able to confirm the binary nature of the (ALS 1135) system and detect four new binary star candidates. Analysis of data for massive Bo 7 star candidates points towards a young age (<=3x10^6^ years old) for the association, although the presence of a previous episode of star formation remains to be analyzed.
129. BV photometry of LW 55 in LMC
ID:
ivo://CDS.VizieR/J/AJ/126/237
Title:
BV photometry of LW 55 in LMC
Short Name:
J/AJ/126/237
Date:
21 Oct 2021
Publisher:
CDS
Description:
The field of the moderately old open cluster LW 55 in the outer parts of the Large Magellanic Cloud disk was monitored for detection of short-period variable stars over two nights. Eight variables were found; all but one (a detached eclipsing binary) are small-amplitude ({Delta}V<=0.1mag) pulsating stars of the {delta} Scuti, SX Phoenicis, or Doradus type. The BV color-magnitude diagram extends down to the solar-type stars at V=24 (M_V_~5.2). The cluster age is estimated at 1.5Gyr for Z=0.004 ([Fe/H]=-0.67); the surrounding stellar field is older, with an age greater than 4Gyr.
130. BV photometry of M11 stars
ID:
ivo://CDS.VizieR/J/PASP/119/1233
Title:
BV photometry of M11 stars
Short Name:
J/PASP/119/1233
Date:
21 Oct 2021
Publisher:
CDS
Description:
V-band time-series CCD photometric observations of the intermediate-age open cluster M11 were performed to search for variable stars.

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