- ID:
- ivo://CDS.VizieR/J/A+A/528/A127
- Title:
- Radial velocities in the globular NGC 2808
- Short Name:
- J/A+A/528/A127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation mechanism of hot horizontal branch (HB) stars is still one of the most uncertain points of stellar evolution theories. In the past decade, models based on their binary origin have been very successful in reproducing the properties of field subdwarf-B stars, but the observations of their analogues in globular clusters has posed new problems. In addition, the discovery of multiple populations offered an appealing alternative scenario for the formation of these stars. We search for binaries of period P<=200days among a sample of 83 blue horizontal branch stars (Teff=12000-22000K) in NGC 2808, a cluster known to host three distinct stellar populations and a multimodal horizontal branch. The final sample, after the rejection of stars with incomplete observations or poor quality data, consists of 64 targets. The radial velocity of the targets was measured in fourteen epochs, spanning a temporal interval of ~75days. The significant variations were identified by means of a detailed error analysis and a statistical study.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/525/A148
- Title:
- Radial velocities in two globular clusters
- Short Name:
- J/A+A/525/A148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters are useful for testing the validity of Newtonian dynamics in the low acceleration regime typical of galaxies, without the complications of non-baryonic dark matter. In the absence of disturbing effects, such as tidal heating, the velocity dispersion of globular clusters is expected to vanish at large radii. If this is not observed, and in particular if, as observed in elliptical galaxies, the dispersion is found to be constant at large radii below a certain threshold acceleration, this might indicate a breakdown of Newtonian dynamics. To minimize the effects of tidal heating that can increase the velocity dispersion at large radii, we study the velocity dispersion profile of two distant globular clusters, NGC 1851 and NGC 1904. The velocity dispersion profile is derived from accurate radial velocity measurements, obtained at the ESO 8m VLT telescope with the FLAMES multi-object spectrograph. Reliable data for 184 and 146 bona fide cluster star members were obtained for NGC 1851 and NGC 1904, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/798/23
- Title:
- Radial velocities of giant stars in NGC 6388
- Short Name:
- J/ApJ/798/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocity measurements for 82 stars, members of the Galactic globular cluster (GC) NGC 6388, obtained from ESO-VLT K-band Multi Object Spectrograph (KMOS) spectra acquired during the instrument Science Verification. The accuracy of the wavelength calibration is discussed and a number of tests of the KMOS response are presented. The cluster systemic velocity obtained (81.3+/-1.5km/s) is in very good agreement with previous determinations. While a hint of ordered rotation is found between 9" and 20" from the cluster center, where the distribution of radial velocities is clearly bimodal, more data are needed before drawing any firm conclusions. The acquired sample of radial velocities has also been used to determine the cluster velocity dispersion (VD) profile between ~9" and 70", supplementing previous measurements at r<2" and r>60" obtained with ESO-SINFONI and ESO-FLAMES spectroscopy, respectively. The new portion of the VD profile nicely matches the previous ones, better defining the knee of the distribution. The present work clearly shows the effectiveness of a deployable integral field unit in measuring the radial velocities of individual stars for determining the VD profile of Galactic GCs. It represents the pilot project for an ongoing large program with KMOS and FLAMES at the ESO-VLT, aimed at determining the next generation of VD and rotation profiles for a representative sample of GCs.
- ID:
- ivo://CDS.VizieR/J/A+A/448/155
- Title:
- Radial velocities of Leo I globular clusters
- Short Name:
- J/A+A/448/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- VLT/FLAMES radial velocities for 50 Globular Clusters (GCs), 37 field stars and 21 unclassified objects around the Leo I group galaxies NGC 3379 and NGC 3384 are presented. Object Id and BVR photometry are from Rhode & Zepf (2004AJ....127..302R). Positions (J2000.0) should be accurate to ~0"2 or better w.r.t. the GSC2.1 catalogue. Heliocentric radial velocities and their errors were estimated by fitting the peak (see the width, heigh, and Tonry & Davies (1979AJ.....84.1511T) coefficient) of the cross-correlation function (CCF) with the IRAF/RV package task FXCOR, using simulatenous and ELODIE library stellar templates. Objects have been assigned three quality class, class A being the most secure velocity determination, and class C the least secure; the latter objects require confirmation, and such GCs were not considered for the dynamical analysis presented in the paper.
- ID:
- ivo://CDS.VizieR/J/A+A/456/985
- Title:
- Radial velocities of 76 M31 candidate clusters
- Short Name:
- J/A+A/456/985
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a large spectroscopic survey of globular clusters and candidate globular clusters in the nearby M31 galaxy. The survey is aimed at the classification of known candidate M31 clusters and at the study of their kinematic properties. We obtained low-resolution spectroscopy for 133 targets, including 76 yet-to-be-confirmed candidate clusters (i.e. with no previous spectroscopic information), 55 already-confirmed genuine M31 clusters, and 2 uncertain candidates. Our observations allowed a reliable estimate of the target radial velocity, within a typical accuracy of ~+/-20Km/s. The observed candidates have been robustly classified according to their radial velocity and shape parameters that allowed us to confidently discriminate between point sources and extended objects even from low-spatial-resolution imagery. In our set of 76 candidate clusters we found: 42 newly-confirmed bona-fide M31 clusters, 12 background galaxies, 17 foreground Galactic stars, 2 HII regions belonging to M31 and 3 unclassified (possibly M31 clusters or foreground stars) objects. The classification of a few other candidates not included in our survey has been also reassessed on various observational bases. All the sources of radial velocity estimates for M31 known globular clusters available in the literature have been compared and checked, and a homogeneous general list has been obtained for 349 confirmed clusters with radial velocity. Our results suggest that a significant number of genuine clusters (~>100) is still hidden among the plethora of known candidates proposed by various authors. Hence our knowledge of the globular cluster system of the M31 galaxy is still far from complete even in terms of simple membership.
- ID:
- ivo://CDS.VizieR/J/ApJ/591/850
- Title:
- Radial velocities of M49 globular clusters
- Short Name:
- J/ApJ/591/850
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Low Resolution Imaging Spectrometer on the Keck I and II telescopes, we have measured radial velocities for 196 globular clusters (GCs) around M49 (NGC 4472), the brightest member of the Virgo Cluster. Combined with published data, they bring the total number of GCs with measured radial velocities in this galaxy to 263. In terms of sample size, spatial coverage, velocity precision, and the availability of metallicity estimates from Washington photometry, this radial velocity database resembles that presented recently for M87 (NGC 4486), Virgo's cD galaxy and its second-ranked member. We extract the projected kinematics of the full sample of GCs and of separate subsamples of 158 metal-poor and 105 metal-rich GCs.
- ID:
- ivo://CDS.VizieR/J/AJ/149/53
- Title:
- Radial velocities of 12 Milky Way globular clusters
- Short Name:
- J/AJ/149/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present central velocity dispersions, masses, mass-to-light ratios (M/Ls), and rotation strengths for 25 Galactic globular clusters (GCs). We derive radial velocities of 1951 stars in 12 GCs from single order spectra taken with Hectochelle on the MMT telescope. To this sample we add an analysis of available archival data of individual stars. For the full set of data we fit King models to derive consistent dynamical parameters for the clusters. We find good agreement between single-mass King models and the observed radial dispersion profiles. The large, uniform sample of dynamical masses we derive enables us to examine trends of M/L with cluster mass and metallicity. The overall values of M/L and the trends with mass and metallicity are consistent with existing measurements from a large sample of M31 clusters. This includes a clear trend of increasing M/L with cluster mass and lower than expected M/Ls for the metal-rich clusters. We find no clear trend of increasing rotation with increasing cluster metallicity suggested in previous work.
- ID:
- ivo://CDS.VizieR/J/A+A/569/A41
- Title:
- Radial velocities of NGC1316 globular clusters
- Short Name:
- J/A+A/569/A41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The merger remnant NGC 1316 (Fornax A) is one of the most important objects regarding the investigation of and thus an important object to study merger-related processes. A recent photometric study used globular clusters in NGC 1316 to constrain its star formation history, but without the knowledge of individual radial velocities. The kinematical properties of the globular cluster system in comparison with the diffuse stellar light might give more insight into the formation of NGC 1316. Of particular interest is the dark matter content. Planetary nebulae in NGC 1316 indicate a massive dark halo, and globular cluster velocities provide independent evidence. We aim at measuring radial velocities of globular clusters in NGC 1316. We use these kinematical data to investigate the global structure of NGC 1316 and to constrain the dark matter content. We perform multiobject spectroscopy with VLT/FORS2 and MXU. Out of 562 slits, we extract radial velocities for 177 globular clusters. Moreover, we measure radial velocities of the integrated galaxy light, using slits with a sufficiently bright sky. To these data, we add 20 cluster velocities from the literature. In an appendix, we identify new morphological features of NGC 1316 and its companion galaxy NGC 1317.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1119
- Title:
- Radial velocities of NGC 5466 members
- Short Name:
- J/AJ/140/1119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present low-resolution (R~850) spectra for 67 asymptotic giant branch (AGB), horizontal branch, and red giant branch (RGB) stars in the low-metallicity globular cluster NGC 5466, taken with the VIRUS-P integral-field spectrograph at the 2.7m Harlan J. Smith telescope at McDonald Observatory.
- ID:
- ivo://CDS.VizieR/J/AJ/136/506
- Title:
- Radial velocities of {omega} Centauri members
- Short Name:
- J/AJ/136/506
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the two-degree field (2dF) multi-fiber spectrograph of the Anglo-Australian Telescope (AAT) to search for candidate members of the unusual globular cluster omega Centauri at and beyond the cluster tidal radius. Velocities with an accuracy of ~10km/s were obtained for 4105 stars selected to lie in the vicinity of the lower giant branch in the cluster color-magnitude diagram (CMD) and which cover an area on the sky of ~2.4x3.9{deg}^2^ centered on the cluster.
