- ID:
- ivo://CDS.VizieR/J/AJ/109/1086
- Title:
- VI Photometry in M54 and Sgr Dwarf Galaxy
- Short Name:
- J/AJ/109/1086
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VI CCD color-magnitude diagrams for the globular cluster M54 and the Sagittarius dwarf galaxy. These are used to derive the following quantities: [Fe/H] = -1.79 +/- 0.08 for M54 and [Fe/H] = -0.52 +/- 0.09 for Sagittarius. We find a metallicity dispersion of +/- 0.16 dex in M54, and we infer the possible existence of a [Fe/H] ~ -1.3 component in Sagittarius, which may have a metallicity dispersion as well. The mean reddening in the direction of M54 is E(B-V) = 0.13 +/- 0.02. The distances to M54 and Sagittarius, determined using their horizontal branch magnitudes, are identical to within the uncertainties of existing RR Lyrae luminosity-abundance relations. This, together with positional and radial velocity arguments, suggests that M54 is physically associated with Sagittarius. We note that M54 is substantially brighter than the globular cluster members of the Fornax dwarf spheroidal galaxy, and that the metal abundance of Sagittarius is quite high for its estimated absolute magnitude.
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- ID:
- ivo://CDS.VizieR/J/AJ/110/652
- Title:
- VI photometry in NGC 6352
- Short Name:
- J/AJ/110/652
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The globular cluster NGC 6352, which on the basis of its Galactic position, radial velocity, and [Fe/H] is a member of the (thick) disk system of globular clusters, has been observed to below the main-sequence turnoff (MSTO) using the Hubble Space Telescope. These observations, which were obtained before the repair mission, were analyzed using the flux-conserving iterative/recursive deconvolution algorithm developed at the University of North Carolina. This algorithm can produce more precise photometry than standard PSF-fitting methods with the aberrated images. The V, (V-Ic) color-magnitude diagram constructed from these observations places the cluster turnoff at V=18.80+/-0.10. Observations with the CTIO 0.9m telescope have been used to photometer the brighter stars in the cluster, providing a calibration of the HST data and an estimate of the cluster's reddening, E(B-V)=0.21+/-0.03. From spectroscopic observations of the strengths of the Ca II triplet lines in red giants in the cluster and from previous measurements in the literature, we find that NGC 6352 is only slightly more metal rich (Delta[Fe/H]=0.08+/-0.05) than the prototypical disk globular cluster, 47 Tuc. From the difference in V magnitude between the horizontal branch and the MSTO, we find that NGC 6352 is essentially the same age as 47 Tuc (formally, older by 0.7+/-2.2Gyr). Comparisons with the latest Yale isochrones support this result and yield 14.5+/-2Gyr for the age of 47 Tuc from the photometry of Hesser et al. (1987PASP...99..739H), which is consistent with other determinations. The old age obtained for NGC 6352 provides additional evidence that the disk system of globular clusters is very old and is in fact older or comparable in age to several globular clusters populating the Galactic halo.
- ID:
- ivo://CDS.VizieR/J/A+AS/106/161
- Title:
- (V,I) photometry in NGC 6356 and 47 Tuc
- Short Name:
- J/A+AS/106/161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry in the VRI and Gunn z bands was obtained for the populous bulge globular cluster NGC 6356. The analysis of the red giant branch indicates that it is metal-rich, intermediate between 47 Tuc and NGC 6528; we estimate [Fe/H]=~-0.4. The red giant clump is clearly detected. The horizontal branch morphology is red and compact. We derive a reddening of E(B-V)=0.2410.04 and a distance d=15.010.4kpc from the Sun. We also present VI colour magnitude diagrams of 47 Tuc for comparison. NGC 6356 and 47 Tuc are important reference objects for studies of more reddened metal-rich bulge clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/131/2538
- Title:
- VI Photometry of globular cluster Palomar 11
- Short Name:
- J/AJ/131/2538
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometry for the Galactic thick-disk globular cluster Palomar 11 extending well past the main-sequence turnoff in the V and I bands.
- ID:
- ivo://CDS.VizieR/J/MNRAS/343/665
- Title:
- VI photometry of globular cluster systems
- Short Name:
- J/MNRAS/343/665
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have studied the globular cluster systems of seven giant, edge-on spiral galaxies using Hubble Space Telescope imaging in V and I. The galaxy sample covers the Hubble types Sa to Sc, allowing us to study the variation of the properties of globular cluster systems along the Hubble sequence.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A13
- Title:
- VI photometry of globular ESO 37-1
- Short Name:
- J/A+A/581/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the Milky Way, most globular clusters are highly conspicuous objects that were found centuries ago. However, a few dozen of them are faint, sparsely populated systems that were identified largely during the second half of the past century. One of the faintest is ESO 37-1 (E 3) and as such it remains poorly studied, with no spectroscopic observations published so far although it was discovered in 1976. We investigate the globular cluster E3 in an attempt to better constrain its fundamental parameters. Spectroscopy of stars in the field of E3 is shown here for the first time. Deep, precise VI CCD photometry of E3 down to V~26mag is presented and analysed. Low-resolution, medium signal-to-noise ratio spectra of nine candidate members are studied to derive radial velocity and metallicity. Proper motions from the UCAC4 catalogue are used to explore the kinematics of the bright members of E3. Isochrone fitting indicates that E3 is probably very old, with an age of about 13Gyr; its distance from the Sun is nearly 10kpc. It is also somewhat metal rich with [Fe/H]=-0.7. Regarding its kinematics, our tentative estimate for the proper motions is ({mu}_{alpha}*cos{delta}, {mu}_{delta}_=(-7.0+/-0.8, 3.5+/-0.3)mas/yr (or a tangential velocity of 382+/-79km/s) and for the radial velocity 45+/-5km/s in the solar rest frame. E3 is one of the most intriguing globular clusters in the Galaxy. Having an old age and being metal rich is clearly a peculiar combination, only seen in a handful of objects like the far more conspicuous NGC 104 (47 Tucanae). In addition, its low luminosity and sparse population make it a unique template for the study of the final evolutionary phases in the life of a star cluster. Unfortunately, E3 is among the most elusive and challenging known globular clusters because field contamination severely hampers spectroscopic studies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/423/2260
- Title:
- VI photometry of M15 core
- Short Name:
- J/MNRAS/423/2260
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution I-band imaging of the core of the globular cluster M15 obtained at the 2.5-m Nordic Optical Telescope with FastCam, a low readout noise L3CCD-based instrument. Short exposure times (30ms) were used to record 200000 images (512x512 pixels each) over a period of 2h and 43min. The lucky imaging technique was then applied to generate a final image of the cluster centre with full width at half-maximum ~0.1arcsec and 13x13arcsec^2^ field of view. We obtained a catalogue of objects in this region with a limiting magnitude of I=19.5. I-band photometry and astrometry are reported for 1181 stars. This is the deepest I-band observation of the M15 core at this spatial resolution.
- ID:
- ivo://CDS.VizieR/J/A+A/366/498
- Title:
- VI photometry of M33 star clusters
- Short Name:
- J/A+A/366/498
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have detected 102 star clusters in M 33, from 35 deep Hubble Space Telescope (HST) WFPC2 fields taken from our program and from the HST archive. Twenty-eight fields have V and I band imaging, and an additional seven fields are imaged in a single V filter. Eighty-two of the clusters were previously unknown. Integrated photometry reveals that 25 clusters have (V-I) colors typical of those found in Galactic globular clusters (only ten of these objects were previously known). Our discovery of 15 new globular cluster candidates increases previous estimates of the old cluster population in M 33 by ~60%. An additional eleven objects (only two were previously known) have colors expected for intermediate age clusters. The new clusters have a range of ages from 6 million years to >15Gyrs, and masses between 10^2^M_{sun}_-10^6^M_{sun}_, although these parameters are estimated from only one color.
- ID:
- ivo://CDS.VizieR/J/A+A/507/803
- Title:
- VI photometry of new M53 variables
- Short Name:
- J/A+A/507/803
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the variable star content of the globular cluster M53 to compute the physical parameters of the constituting stars and the distance of the cluster. Covering two adjacent seasons in 2007 and 2008, new photometric data are gathered for 3048 objects in the field of M53. By using the OIS (optimal image subtraction) method and subsequently TFA (trend filtering algorithm), we search for variables in the full sample by using discrete Fourier transformation and box-fitting least squares method. We select variables based on the statistics related to these methods combined with visual inspection. We identified 12 new variables (2 RR Lyrae stars, 7 short periodic stars - 3 of them are SX Phe stars - and 3 long-period variables). No eclipsing binaries were found in the present sample. Except for the 3 (hitherto unknown) Blazhko RR Lyrae (two RRab and an RRc) stars, no multiperiodic variables were found. We showed that after proper period shift, the PLC (period-luminosity-color) relation for the first overtone RR Lyrae sample tightly follows the one spanned by the fundamental stars. Furthermore, the slope is in agreement with that derived from other clusters. Based on the earlier Baade-Wesselink calibration of the PLC relations, the derived reddening-free distance modulus of M53 is 16.31+/-0.04mag, corresponding to a distance modulus of 18.5mag for the Large Magellanic Cloud. From the Fourier parameters of the RRab stars we obtained an average iron abundance of -1.58+/-0.03 (error of the mean). This is ~0.5dex higher than the overall abundance of the giants as given in the literature and derived in this paper from the three-color photometry of giants. We suspect that the source of this discrepancy (observable also in other, low-metallicity clusters) is the lack of a sufficient number of low-metallicity objects in the calibrating sample of the Fourier method.
- ID:
- ivo://CDS.VizieR/J/AJ/124/915
- Title:
- VI photometry of NGC 5634
- Short Name:
- J/AJ/124/915
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first (V, V-I) color-magnitude diagram (CMD) for the poorly studied globular cluster NGC 5634. The CMD shows a steep red giant branch (RGB) and a predominantly blue horizontal branch (HB): both these characteristics suggest a low metal content for this cluster. The data were obtained at the 3.52 m Italian Telescopio Nazionale Galileo (Roque de los Muchachos, La Palma, Canary Islands, Spain), using the LSR DoLoRes Camera equipped with a 2048x2048 pixel thinned and back-illuminated Loral CCD array.
