- ID:
- ivo://CDS.VizieR/J/A+A/576/A14
- Title:
- VEGAS-SSS photometry of NGC3115
- Short Name:
- J/A+A/576/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of globular clusters (GCs) and other small stellar systems (SSSs) in the field of NGC 3115, observed as part of the ongoing wide-field imaging survey VEGAS, carried out with the 2.6m VST telescope. We used deep g and i observations of NGC 3115, a well-studied lenticular galaxy that is covered excellently well in the scientific literature. This is fundamental to test the methodologies, verify the results, and probe the capabilities of the VEGAS-SSS. Leveraging the large field of view of the VST allowed us to accurately study the distribution and properties of SSSs as a function of galactocentric distance, well beyond ~20 galaxy effective radii, in a way that is rarely possible. Our analysis of colors, magnitudes, and sizes of SSS candidates confirms the results from existing studies, some of which were carried out with 8-10m class telescopes, and further extends them to previously unreached galactocentric distances with similar accuracy. In particular, we find a color bimodality for the GC population and a de Vaucouleurs profile for the surface density of GCs similar to the galaxy light profile. The radial color gradient of blue and red GCs previously found, for instance, by the SLUGGS survey with Subaru and Keck data, is further extended out to the largest galactocentric radii inspected, ~65kpc. In addition, the surface density profiles of blue and red GCs taken separately are well approximated by a r1/4 density profile, with the fraction of blue GCs being slightly larger at larger radii. We do not find hints of a trend for the red GC subpopulation and for the GC turnover magnitude to vary with radius, but we observe a ~0.2mag difference in the turnover magnitude of the blue and red GC subpopulations. Finally, from inspecting SSS sizes and colors, we obtain a list of ultracompact dwarf galaxies and GC candidates suitable for future spectroscopic follow-up. In conclusion, our study shows i) the reliability of the methodologies developed to study SSSs in the field of bright early-type galaxies, and ii) the great potential of the VEGAS survey to produce original results on SSSs science, mainly thanks to the wide-field imaging adopted.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/133/1041
- Title:
- Velocities and CMT2 photometry in globular M92
- Short Name:
- J/AJ/133/1041
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the determination of high-accuracy radial velocities for 306 members of the globular cluster M92 using the Hydra multiobject spectrograph on the WIYN telescope. We have concentrated on stars outside of the central region of the cluster, located up to 14.4' from the cluster center. Candidate members were selected for spectroscopy based on a photometric metallicity index determined from three-band Washington photometry, also obtained with the WIYN telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/464/L21
- Title:
- Velocities of globular clusters in Fornax
- Short Name:
- J/A+A/464/L21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We acquired radial velocities of a significant number of globular clusters (GCs) on wide fields between galaxies in the nearby Fornax cluster of galaxies, in order to derive their velocity dispersion radial profile and to probe the dynamics of the cluster. We used FLAMES on the VLT to obtain accurate velocities for 149 GCs, within a ~500x150kpc strip centered on NGC 1399, the Fornax central galaxy. These objects are at the very bright tail (M_V_<~-9.5) of the GC luminosity function, overlapping the so-called "ultra-compact dwarfs" magnitude range. Eight of the brightest FLAMES-confirmed members indeed show hints of resolution in the subarcsecond pre-imaging data we used for selecting the ~500 targets for FLAMES spectroscopy.
- ID:
- ivo://CDS.VizieR/J/AJ/147/150
- Title:
- Velocities of globular clusters in M104
- Short Name:
- J/AJ/147/150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained radial velocity measurements for 51 new globular clusters around the Sombrero galaxy. These measurements were obtained using spectroscopic observations from the AAOmega spectrograph on the Anglo-Australian Telescope and the Hydra spectrograph at WIYN. Combining our own past measurements and velocity measurements obtained from the literature, we have constructed a large database of radial velocities that contains a total of 360 confirmed globular clusters. Previous studies' analyses of the kinematics and mass profile of the Sombrero globular cluster system have been constrained to the inner ~9' (~24kpc or ~5R_e_), but our new measurements have increased the radial coverage of the data, allowing us to determine the kinematic properties of M104 out to ~15' (~41kpc or ~9R_e_). We use our set of radial velocities to study the GC system kinematics and to determine the mass profile and V-band mass-to-light profile of the galaxy. We find that M/L_V_ increases from 4.5 at the center to a value of 20.9 at 41kpc (~9R_e_ or 15'), which implies that the dark matter halo extends to the edge of our available data set. We compare our mass profile at 20kpc (~4R_e_or ~7.4') to the mass computed from X-ray data and find good agreement. We also use our data to look for rotation in the globular cluster system as a whole, as well as in the red and blue subpopulations. We find no evidence for significant rotation in any of these samples.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A115
- Title:
- Velocities of NGC 4636 globular clusters
- Short Name:
- J/A+A/544/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocities for 289 globular clusters around NGC 4636, the southernmost giant elliptical galaxy of the Virgo cluster. The data were obtained with FORS2/MXU at the Very Large Telescope. Together with data analysed in an earlier study, we now have a sample of 460 globular cluster velocities out to a radius of 12-arcmin (60kpc) available - one of the largest of its kind. This new data set also provides a much more complete angular coverage. Moreover, we present new kinematical data of the inner stellar population of NGC 4636. We perform an updated Jeans analysis, using both stellar and GC data, to better constrain the dark halo properties.
- ID:
- ivo://CDS.VizieR/J/A+A/513/A52
- Title:
- Velocities of NGC 1399 globular clusters
- Short Name:
- J/A+A/513/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters (GCs) are tracers of the gravitational potential of their host galaxies. Moreover, their kinematic properties may provide clues for understanding the formation of GC systems and their host galaxies. We use the largest set of GC velocities obtained so far of any elliptical galaxy to revise and extend the previous investigations (Richtler et al., 2004AJ....127.2094R) of the dynamics of NGC 1399, the central dominant galaxy of the nearby Fornax cluster of galaxies. The GC velocities are used to study the kinematics, their relation with population properties, and the dark matter halo of NGC 1399. We have obtained 477 new medium-resolution spectra (of these, 292 are spectra from 265 individual GCs, 241 of which are not in the previous data set). with the VLT FORS 2 and Gemini South GMOS multi--object spectrographs. We revise velocities for the old spectra and measure velocities for the new spectra, using the same templates to obtain an homogeneously treated data set. Our entire sample now comprises velocities for almost 700 GCs with projected galactocentric radii between 6 and 100kpc. In addition, we use velocities of GCs at larger distances published by Bergond et al. (2007, Cat. J/A+A/464/L21). Combining the kinematic data with wide-field photometric Washington data, we study the kinematics of the metal-poor and metal--rich subpopulations. We discuss in detail the velocity dispersions of subsamples and perform spherical Jeans modelling.
- ID:
- ivo://CDS.VizieR/J/A+A/319/850
- Title:
- V, I , and Gunn z imaging of Terzan 4
- Short Name:
- J/A+A/319/850
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the globular cluster Terzan 4 projected close to the Galactic center, by means of V, I and Gunn z Colour-Magnitude Diagrams. The images were obtained under exceptional seeing conditions (0.35"-0.55") at the ESO New Technology Telescope equipped with SUSI. We derive a reddening of E(B-V)=2.35 and a distance from the Sun d_{sun}_=8.3kpc for Terzan 4. From the similarity of the VI Colour-Magnitude Diagrams of Terzan 4 and M30, in particular the presence of a blue horizontal branch, it could be as metal-poor as [Fe/H]=~-2.0. It is therefore another blue horizontal branch globular cluster located close to the Galactic center.
- ID:
- ivo://CDS.VizieR/J/A+AS/127/167
- Title:
- V,I CCD photometry of NGC 6528
- Short Name:
- J/A+AS/127/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD photometry in V and I for the metal-rich globular cluster NGC 6528. A comparison with previous photometry reveals discrepancies of the order 0.1 to 0.2mag in V, emphasizing the need for independent photometry. As found previously, the giant branch (or the asymptotic giant branch, which cannot be distinguished) of the cluster extends to V-I=7. Population synthesis in V-I must take these red stars into account in order to understand integrated red colours of bulge populations. Currently available theoretical isochrones do not reproduce the shape of the RGB/AGB. The derivation of reliable values for reddening, distance and metallicity of NGC 6528 is hampered by uncertainties in the extrapolation to high metallicity, which dominate the absolute error rather than the photo metric uncertainty does. Together with other properties (old age derived from HST data, high radial velocity), this object is more likely a member of the bulge than of the disk population.
- ID:
- ivo://CDS.VizieR/J/A+AS/135/391
- Title:
- VI CCD photometry of NGC 6553
- Short Name:
- J/A+AS/135/391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- X, Y pixel coordinates and V, I CCD photometric magnitudes of stars in cluster region NGC 6553. DAOPHOT photometric errors in V and (V-I) are also given.
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/730
- Title:
- VIJK photometry of Whiting 1 stars
- Short Name:
- J/MNRAS/446/730
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Whiting 1 is a member of the fast-growing group of young globular clusters in the Milky Way halo. Preliminary estimates of its fundamental parameters have been provided using optical photometry and low-resolution spectroscopy. In an attempt to strengthen our knowledge of Whiting 1, in this study we employ a complementary approach. Isochrone fitting method was applied on the near-infrared colour-magnitude diagram and yields an age t=5.7+/-0.3Gyr, metallicity z=0.006+/-0.001 ([Fe/H]=-0.5+/-0.1) and distance modulus (m-M)0=17.48+/-0.10. Our results confirm that Whiting 1 is a young and moderately metal-rich globular cluster. It is one of the youngest from the Sgr dSph. We fitted an Elson, Fall and Freeman (EFF) profile to the near-infrared number counts, and measured cluster core radius r_c_=9.1+/-3.9". Two probable eclipsing variables in the cluster were found from multi-epoch V-band photometry. Finally, an unknown galaxy cluster was identified on our K versus (J-K) colour-magnitude diagram. It has a redshift z~1, and it is located at about 1arcmin from the centre of Whiting 1 at {alpha}_J2000_= 02:02:56.6, {delta}_J2000_=-03:16:09, contaminating the cluster photometry.
