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- ID:
- ivo://CDS.VizieR/J/A+A/615/A96
- Title:
- VI photometry in 3 dwarf galaxies
- Short Name:
- J/A+A/615/A96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundance and spatial distribution of dwarf galaxies are excellent empirical benchmarks against which to test models of structure formation on small scales. The nearby Centaurus group, with its two subgroups centered on Cen A and M 83, stands out as an important alternative to the Local Group for scrutinizing cosmological model predictions in a group of galaxies context. We have obtained deep optical images of three recently discovered M 83 satellite galaxy candidates with the FORS2 instrument mounted on the Very Large Telescope. We aim to confirm their group membership and study their stellar population. Deep V I-band photometry was used to resolve the brightest stars in our targets. Artificial star tests are performed to estimate the completeness and uncertainties of the photometry. The color-magnitude diagrams reveal the red giant branch (RGB) stars, allowing us to use the Sobel edge detection method to measure the magnitude of the RGB tip and thus derive distances and group membership for our targets. The mean metallicity of the dwarf galaxies were further determined by fitting BASTI model isochrones to the mean RGB locus.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/396/473
- Title:
- VI Photometry in M81 Group
- Short Name:
- J/A+A/396/473
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive quantitative star formation histories of the four suspected tidal dwarf galaxies in the M 81 group, Holmberg IX, BK3N, Arp-loop (A0952+69), and Garland, using Hubble Space Telescope/Wide Field Planetary Camera 2 images in F606W and F814W obtained as part of a Snapshot survey of dwarf galaxies in the Local Universe.
- ID:
- ivo://CDS.VizieR/J/AJ/128/224
- Title:
- VI photometry in M33 outer regions
- Short Name:
- J/AJ/128/224
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep CCD photometry in the VI passbands using the WIYN 3.5m telescope of a field located approximately 20 southeast of the center of M33; this field includes the region studied by Mould & Kristian in 1986ApJ...305..591M. The color-magnitude diagram (CMD) extends to I~25 and shows a prominent red giant branch (RGB), along with significant numbers of asymptotic giant branch and young main-sequence stars.
7856. VI photometry in NGC 188
- ID:
- ivo://CDS.VizieR/J/A+A/390/961
- Title:
- VI photometry in NGC 188
- Short Name:
- J/A+A/390/961
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used HST-WFPC2 to study the white dwarf luminosity function of the old open cluster NGC 188 in order to determine a lower limit to the age of the cluster (~5Gyr) by looking at the faint end of the cooling sequence (down to V~26.5).
- 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/MNRAS/424/1113
- Title:
- VI photometry in Phoenix dwarf galaxy
- Short Name:
- J/MNRAS/424/1113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a wide-area photometric survey of the Phoenix dwarf galaxy, one of the rare dwarf irregular/dwarf spheroidal transition-type galaxies (dTs) of the Local Group (LG). These objects offer the opportunity to study the existence of possible evolutionary links between the late- and early-type LG dwarf galaxies, since the properties of dTs suggest that they may be dwarf irregulars in the process of transforming into dwarf spheroidals. Using FORS at the Very Large Telescope (VLT), we have acquired VI photometry of Phoenix. The data reach a signal-to-noise ratio (S/N)~10 just below the horizontal branch of the system and consist of a mosaic of images that covers an area of 26x26arcmin^2^ centred on the coordinates of the optical centre of the galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/390/931
- Title:
- VI photometry in Pismis 23 and Stephenson 2
- Short Name:
- J/A+A/390/931
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Pismis 23 and Stephenson 2 are two very reddened open clusters, projected close to the Galactic plane. We present VI and JH photometry for Pismis 23 and I and Gunn z for Stephenson 2. We derive a relatively old age of ~700Myr for Pismis 23, with a reddening value of E(B-V)=1.73 and a distance d_{sun}_~2.6kpc from the Sun. Stephenson 2 has a clump of red supergiants, indicating a young age of about 20Myr, somewhat younger and more distant (d_{sun}_~6kpc) than recently reported in the literature. The age estimate for such a young object is crucial for the distance estimate. The high reddening of these two clusters relative to predictions from the diffuse interstellar medium at their distances is due to discrete intervening clouds.
