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- ID:
- ivo://CDS.VizieR/J/MNRAS/364/179
- Title:
- BVI photometry of 8 open clusters
- Short Name:
- J/MNRAS/364/179
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD BVI photometry is presented for eight previously unstudied star clusters located in the first and fourth Galactic quadrants: AL 1, BH 150, NGC 5764, Lynga 9, Czernik 37, BH 261, Berkeley 80 and King 25. Colour-magnitude diagrams of the cluster regions suggest that several of them (BH 150, Lynga 9, Czernik 37, BH 261 and King 25) are so embedded in the dense stellar population toward the galactic centre that their properties, or even their existence as physical systems, cannot be confirmed. Lynga 9, BH 261 and King 25 appear to be slight enhancements of dense star fields, BH 150 is probably just a single bright star in a dense field and Czernik 37 may be a sparse, but real cluster superimposed on the galactic bulge population. We derive preliminary estimates of the physical parameters for the remaining clusters. AL 1 appears to be an intermediate-age cluster beyond the solar circle on the far side of the galaxy and the final two clusters, NGC 5764 and Berkeley 80, are also of intermediate age but located inside the solar ring. This set of clusters highlights the difficulties inherent in studying the stellar populations toward the inner regions of the galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/360/655
- Title:
- BVI photometry of 3 open clusters
- Short Name:
- J/MNRAS/360/655
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on BVI CCD photometry to V=22.0 for three fields centred on the region of the Galactic star clusters Ruprecht 4, Ruprecht 7 and Pismis 15 and on three displaced control fields.
- ID:
- ivo://CDS.VizieR/J/A+A/370/931
- Title:
- BVI photometry of 4 open clusters
- Short Name:
- J/A+A/370/931
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD observations in the B, V and I passbands have been used to generate colour-magnitude diagrams reaching down to V~19mag for two slightly characterized (Melotte 105 and Hogg 15) and two almost unstudied (Pismis 21 and Ruprecht 140) open clusters. The sample consists of about 1300 stars observed in fields of about 4'x4'. Our analysis shows that neither Pismis 21 nor Ruprecht 140 are genuine open clusters since no clear main sequences or other meaningful features can be seen in their colour-magnitude diagrams. Melotte 105 and Hogg 15 are open clusters affected by E(B-V)=0.42+/-0.03 and 0.95+/-0.05, respectively. Their distances to the Sun have been estimated as 2.2+/-0.3 and 2.6+/-0.08kpc, respectively, while the corresponding ages estimated from empirical isochrones fitted to the Main Sequence cluster members are ~350Myr and 300Myr, respectively. The present data are not consistent with the membership of the WN6 star HDE 311884 to Hogg 15.
- ID:
- ivo://CDS.VizieR/J/AJ/148/30
- Title:
- BVI photometry of 350 Pleiades stars
- Short Name:
- J/AJ/148/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new BVI_C_ photometry for 350 Pleiades proper motion members with 9<V<~17. Importantly, our new catalog includes a large number of K- and early M-type stars, roughly doubling the number of low-mass stars with well-calibrated Johnson/Cousins photometry in this benchmark cluster. We combine our new photometry with existing photometry from the literature to define a purely empirical isochrone at Pleiades age ({approx}100Myr) extending from V=9 to 17. We use the empirical isochrone to identify 48 new probable binaries and 14 likely nonmembers. The photometrically identified single stars are compared against their expected positions in the color-magnitude diagram (CMD). At 100Myr, the mid K and early M stars are predicted to lie above the zero-age main sequence (ZAMS) having not yet reached the ZAMS. We find in the B-V versus V CMD that mid K and early M dwarfs are instead displaced below (or blueward of) the ZAMS. Using the stars' previously reported rotation periods, we find a highly statistically significant correlation between rotation period and CMD displacement, in the sense that the more rapidly rotating stars have the largest displacements in the B-V CMD.
- ID:
- ivo://CDS.VizieR/J/MNRAS/371/1301
- Title:
- BVI photometry of six old open clusters
- Short Name:
- J/MNRAS/371/1301
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present the first BVI CCD photometry of six overlooked old open clusters (Berkeley 44, NGC 6827, Berkeley 52, Berkeley 56, Skiff 1 and Berkeley 5) and derive estimates of their fundamental parameters by using isochrones from the Padova library. We found that all the clusters are older than the Hyades, with ages ranging from 0.8Gyr (NGC 6827 and Berkeley 5) to 4.0Gyr (Berkeley 56). The latter is one of the old open clusters with the largest heliocentric distance.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/881/22
- Title:
- BVI photometry of the TypeII SN KSP-SN-2016kf
- Short Name:
- J/ApJ/881/22
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- We present the discovery and the photometric and spectroscopic study of H-rich Type II supernova (SN) KSP-SN-2016kf (SN2017it) observed in the KMTNet Supernova Program in the outskirts of a small irregular galaxy at z~0.043 within a day of the explosion. Our high-cadence, multi-color (BVI) light curves of the SN show that it has a very long rise time (t_rise_~20days in the V band), a moderately luminous peak (M_V_~-17.6mag), a notably luminous and flat plateau (M_V_~-17.4mag and decay slope s~0.53mag per 100 days), and an exceptionally bright radioactive tail. Using the color-dependent bolometric correction to the light curves, we estimate the ^56^Ni mass powering the observed radioactive tail to be 0.10{+/-}0.01M_{sun}_, making it an H-rich Type II SN with one of the largest ^56^Ni masses observed to date. The results of our hydrodynamic simulations of the light curves constrain the mass and radius of the progenitor at the explosion to be ~15M_{sun}_ (evolved from a star with an initial mass of ~18.8M_{sun}_) and ~1040R_{sun}_, respectively, with the SN explosion energy of ~1.3x10^51^erg. The above-average mass of the KSP-SN-2016kf progenitor, together with its low metallicity of Z/Z_{sun}_~0.1--0.4 obtained from spectroscopic analysis, is indicative of a link between the explosion of high-mass red supergiants and their low-metallicity environment. The early part of the observed light curves shows the presence of excess emission above what is predicted in model calculations, suggesting there is interaction between the ejecta and circumstellar material. We further discuss the implications of the high initial mass of the progenitor and the low-metallicity environment of KSP-SN-2016kf for our understanding of the origin of Type II SNe.
- 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'.
- ID:
- ivo://CDS.VizieR/J/AJ/121/870
- Title:
- BVI photometry of Variables in M33
- Short Name:
- J/AJ/121/870
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The DIRECT project aims to determine direct distances to two important galaxies in the cosmological distance ladder - M31 and M33 - using detached eclipsing binaries (DEBs) and Cepheids. We present the results of the first large-scale CCD-based search for variables in M33. We have observed two fields located in the central region of M33 for a total of 95 nights on the F. L. Whipple Observatory 1.2 m telescope and 36 nights on the Michigan-Dartmouth-MIT 1.3 m telescope. We have found a total of 544 variables, including 251 Cepheids and 47 eclipsing binaries. The catalog of variables is available on-line, along with finding charts and BVI light curve data (consisting of 8.2x10^4^ individual measurements). The complete set of CCD frames is available upon request.
