- ID:
- ivo://CDS.VizieR/J/A+A/493/959
- Title:
- UBV(RI)cHalpha photometry in omega Cen
- Short Name:
- J/A+A/493/959
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- omega Centauri is the most well studied Galactic Globular Cluster because of its numerous puzzling features: significant dispersion in metallicity, multiple populations, triple main-sequence, horizontal branch morphology, He-rich population(s), and extended star-formation history. Intensive spectroscopic follow-up observing campaigns targeting stars at different positions in the color-magnitude diagram promises to clarify some of these peculiarities. To be able to target cluster members reliably during spectroscopic surveys and both spatial and radial distributions in the cluster outskirts without including field stars, a high quality proper-motion catalog of omega Cen and membership probability determination are required. The only available wide field proper-motion catalog of omega Cen is derived from photographic plates, and only for stars brighter than B~16. Using ESO archive data, we create a new, CCD-based, proper-motion catalog for this cluster, extending to B~20. We used high precision astrometric software developed specifically for data acquired by WFI@2.2m telescope and presented in the first paper of this series.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/663/296
- Title:
- UBV(RI)c phot. of omega Cen (NGC5139) subgiants
- Short Name:
- J/ApJ/663/296
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine spectroscopic and photometric data for subgiant stars of {omega} Cen to extract results that neither data set could have provided on its own. GIRAFFE@VLT spectra of 80 stars at R=6400 give metallicities for all of them and abundances of C, N, Ca, Ti, and Ba for a subset of them. The photometric data, which have unusually high accuracy, come from a ~10x10arcmin^2^ mosaic of HST ACS images centered on the cluster center and on multicolor images of a ~34x33arcmin^2^ field, taken with the WFI@ESO2.2m camera. Stars with [Fe/H]<-1.25 have a large magnitude spread on the flat part of the sub-giant branch (SGB). We interpret this as empirical evidence for an age spread, and from theoretical isochrones we derive a relative age for each star.
- ID:
- ivo://CDS.VizieR/J/MNRAS/485/3042
- Title:
- UBVRI photometry in 48 globular clusters
- Short Name:
- J/MNRAS/485/3042
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present wide-field, ground-based Johnson-Cousins UBVRI photometry for 48 Galactic globular clusters based on almost 90000 public and proprietary images. The photometry is calibrated with the latest transformations obtained in the framework of our secondary standard project, with typical internal and external uncertainties of order a few millimagnitudes. These data provide a bridge between existing small-area, high-precision HST photometry and all sky-catalogues from large surveys like Gaia, SDSS, or LSST. For many clusters, we present the first publicly available photometry in some of the five bands (typically U and R). We illustrate the scientific potential of the photometry with examples of surface density and brightness profiles and of colour-magnitude diagrams, with the following highlights: (i) we study the morphology of NGC 5904, finding a varying ellipticity and position angle as a function of radial distance; (ii) we show $U$-based colour-magnitude diagrams and demonstrate that no cluster in our sample is free from multiple stellar populations, with the possible exception of a few clusters with high and differential reddening or field contamination, for which more sophisticated investigations are required. This is true even for NGC 5694 and Terzan 8, that were previously considered as (mostly) single-population candidates.
- ID:
- ivo://CDS.VizieR/J/AJ/109/1169
- Title:
- UBVRI sequences in globulars
- Short Name:
- J/AJ/109/1169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVRI photoelectric sequences for three low-latitude galactic globular clusters. NGC 5286, NGC 5927, and NGC 6541, are presented herein. All include fields suitable for CCD coverage. The number of stars and the range of magnitudes and colors are: * NGC 5286: 8 stars 13.6<V<15.3, 0.6<B-V<1.3 (table2) * NGC 5927: 11 stars 11.3<V<14.9, 0.3<B-V<1.6 (table3) * NGC 6541: 16 stars 12.2<V<15.7, 0.2<B-V<1.6 (table4) The stars were measured an average of seven times on at least five different nights. To the best of our knowledge, none of these stars have UBVRI photoelectric measurements reported by other authors.
- ID:
- ivo://CDS.VizieR/J/AJ/121/3114
- Title:
- UBVR photometry of NGC 6712 with VLT
- Short Name:
- J/AJ/121/3114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present extensive UBVR photometry of the Galactic globular cluster (GGC) NGC 6712 obtained with the ESO Very Large Telescope (VLT) which reaches down to 2 mag below the main-sequence turn-off and allows us for the first time to determine the age of this cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/75/167
- Title:
- UBV sequences near 3 globulars
- Short Name:
- J/AJ/75/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results concerning photoelectrically observed UBV magnitudes and colors of bright to intermediately faint stars near three globular clusters (NGC 2808, 5927, and 6101) are assembled.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A72
- Title:
- ubvy photometry of NGC2419
- Short Name:
- J/A+A/581/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 2419 is a peculiar Galactic globular cluster offset from the others in the size-luminosity diagram, and showing several chemical abundance anomalies. Here, we present Stromgren uvby photometry of the cluster. Using the gravity- and metallicity-sensitive c1 and m1 indices, we identify a sample of likely cluster members extending well beyond the formal tidal radius. The estimated contamination by cluster non-members is only one per cent, making our catalogue ideally suited for spectroscopic follow-up. We derive photometric [Fe/H] of red giants, and depending on which metallicity calibration from the literature we use, we find reasonable to excellent agreement with spectroscopic [Fe/H], both for the cluster mean metallicity and for individual stars. We demonstrate explicitly that the photometric uncertainties are not Gaussian and this must be accounted for in any analysis of the metallicity distribution function.
- ID:
- ivo://CDS.VizieR/J/AJ/137/498
- Title:
- UCD and bright GC in Fornax
- Short Name:
- J/AJ/137/498
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- All the previously cataloged ultracompact dwarf (UCD) galaxies in the Fornax and Virgo clusters have 17.5<b_J_<20. Using the 2dF spectrograph on the Anglo-Australian Telescope, we have carried out a search for fainter UCDs in the Fornax Cluster. In the magnitude interval 19.5<b_J_<21.5, we have found 54 additional compact cluster members within a projected radius of 0.9{deg} (320kpc) of the cluster center, all of which meet our selection and observational criteria to be UCDs.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A102
- Title:
- UCDs in the halo of NGC1399
- Short Name:
- J/A+A/586/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a novel approach to constrain the formation channels of ultra-compact dwarf galaxies (UCDs). They most probably are an inhomogeneous class of objects, composed of remnants of tidally stripped dwarf elliptical galaxies and star clusters that occupy the high mass end of the globular cluster luminosity function. We use three methods to unravel their nature: 1) we analyzed their surface brightness profiles; 2) we carried out a direct search for tidal features around UCDs; and 3) we compared the spatial distribution of GCs and UCDs in the halo of their host galaxy. Based on FORS2 observations under excellent seeing conditions, we studied the detailed structural composition of a large sample of 97 UCDs in the halo of NGC1399, the central galaxy of the Fornax cluster, by analyzing their surface brightness profiles. We found that 13 of the UCDs were resolved above the resolution limit of 23pc and we derived their structural parameters fitting a single Sersic function. When decomposing their profiles into composite King and Sersic profiles, we find evidence for faint stellar envelopes at {mu}=~26mag/arcsec^2^, surrounding the UCDs up to an extension of 90pc in radius. We also show new evidence for faint asymmetric structures and tidal tail-like features surrounding several of these UCDs, a possible tracer of their origin and assembly history within their host galaxy halos. In particular, we present evidence for the first discovery of a significant tidal tail with an extension of ~350pc around UCD-FORS2. Finally, we studied the local overdensities in the spatial distribution of globular clusters within the halo of NGC1399 out to 110kpc to see if they are related to the positions of the UCDs. We found a local overabundance of globular clusters on a scale of <=1kpc around UCDs, when we compared it to the distribution of globulars from the host galaxy. This effect is strongest for the metal-poor blue GCs. We discuss how likely it is that these clustered globulars were originally associated with the UCD, either as globular cluster systems of a nucleated dwarf galaxy that was stripped down to its nucleus, or as a surviving member of a merged super star cluster complex.
- ID:
- ivo://CDS.VizieR/J/A+A/531/A4
- Title:
- Ultra compact dwarfs and globulars in Hya I
- Short Name:
- J/A+A/531/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a large spectroscopic survey of compact, unresolved objects in the core of the Hydra I galaxy cluster (Abell 1060), with the aim of identifying ultra-compact dwarf galaxies (UCDs) and investigating the properties of the globular cluster (GC) system around the central cD galaxy NGC 3311. We obtained VIMOS medium-resolution spectra of about 1200 candidate objects with apparent magnitudes 18.5<V<24.0mag, covering both the bright end of the GC luminosity function and the luminosity range of all known UCDs.
