- ID:
- ivo://CDS.VizieR/J/ApJ/681/311
- Title:
- Blue stragglers in NGC 2419
- Short Name:
- J/ApJ/681/311
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used a combination of ACS HST high-resolution and wide-field Subaru data in order to study the blue straggler star (BSS) population over the entire extension of the remote Galactic globular cluster NGC 2419. The BSS population presented here is among the largest ever observed in any stellar system, with more than 230 BSSs in the brightest portion of the sequence. The radial distribution of the selected BSSs is essentially the same as that of the other cluster stars.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/677/1069
- Title:
- Blue stragglers in NGC 6388
- Short Name:
- J/ApJ/677/1069
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used multiband high-resolution HST WFPC2 and ACS observations combined with wide-field ground-based observations to study the blue straggler star (BSS) population in the Galactic globular cluster NGC 6388. As in several other clusters we have studied, the BSS distribution is found to be bimodal: highly peaked in the cluster center, rapidly decreasing at intermediate radii, and rising again at larger radii. In other clusters the sparsely populated intermediate-radius region (or "zone of avoidance") corresponds well to that part of the cluster where dynamical friction would have caused the more massive BSSs or their binary progenitors to settle to the cluster center. Instead, in NGC 6388, BSSs still populate a region that should have been cleaned out by dynamical friction effects, thus suggesting that dynamical friction is somehow less efficient than expected. As a by-product of these observations, the peculiar morphology of the horizontal branch (HB) is also confirmed. In particular, within the (very extended) blue portion of the HB we are able to clearly characterize three subpopulations: ordinary blue HB stars, extreme HB stars, and blue hook stars. Each of these populations has a radial distribution which is indistinguishable from normal cluster stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/797/43
- Title:
- Blue stragglers in {omega} Cen
- Short Name:
- J/ApJ/797/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By using high-resolution spectra acquired with FLAMES-GIRAFFE at the ESO/VLT, we measured the radial and rotational velocities for 110 blue straggler stars (BSSs) in {omega} Centauri, the globular cluster-like stellar system harboring the largest known BSS population. According to their radial velocities, 109 BSSs are members of the system. The rotational velocity distribution is very broad, with the bulk of BSSs spinning at less than ~40 km/s (in agreement with the majority of such stars observed in other globular clusters) and a long tail reaching ~200km/s. About 40% of the sample has v_e_sini>40km/s and about 20% has v_e_sini>70km/s. Such a large fraction is very similar to the percentage of fast rotating BSSs observed in M4. Thus, {omega} Centauri is the second stellar cluster, beyond M4, with a surprisingly high population of fast spinning BSSs. We found a hint of radial behavior for a fraction of fast rotating BSSs, with a mild peak within one core radius, and a possible rise in the external regions (beyond four core radii). This may suggest that recent formation episodes of mass transfer BSSs occurred preferentially in the outskirts of {omega} Centauri, or that braking mechanisms able to slow down these stars are least efficient in the lowest density environments.
- ID:
- ivo://CDS.VizieR/J/ApJ/748/91
- Title:
- Blue straggler stars in M75
- Short Name:
- J/ApJ/748/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used a combination of multiband high-resolution and wide-field ground-based observations to image the Galactic globular cluster M75 (NGC 6864). The extensive photometric sample covers the entire cluster extension, from the very central regions out to the tidal radius, allowing us to determine the center of gravity and to construct the most extended star density profile ever published for this cluster. We also present the first detailed star counts in the very inner regions. The star density profile is well reproduced by a standard King model with core radius r_c_~5.4" and intermediate-high concentration c~1.75. The present paper presents a detailed study of the blue straggler star (BSS) population and its radial distribution. A total of 62 bright BSSs (with m_F255W_<~21, corresponding to m_F555W_<~20) have been identified, and they have been found to be highly segregated in the cluster core. No significant upturn in the BSS frequency has been observed in the outskirts of M75, in contrast to several other clusters studied with the same technique. This observational fact is quite similar to what has been found in M79 (NGC 1904) by Lanzoni et al. (2007ApJ...663.1040L). Indeed, the BSS radial distributions in the two clusters are qualitatively very similar, even if in M75 the relative BSS frequency seems to decrease significantly faster than in M79: it decreases by a factor of five (from 3.4 to 0.7) within 1r_c_. Such evidence indicates that the vast majority of the cluster heavy stars (binaries) have already sunk to the core.
- ID:
- ivo://CDS.VizieR/J/A+AS/121/499
- Title:
- BV and rg photometry of Pal 13
- Short Name:
- J/A+AS/121/499
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new CCD photometry of the halo cluster Palomar 13 is used to construct a color-magnitude diagram in the Thuan-Gunn and the B, V photometric systems. The color-magnitude diagram of the cluster shows as already noted by Ortolani et al. (1985AJ.....90..473O) an extremely poor red horizontal branch and a very sparsely populated giant branch. Seven BSS candidates are identified in the field of Palomar 13. The age of the cluster determined by fitting with the isochrones of Proffitt & Vanden Berg (1991ApJS...77..473P) and Bergbusch & Vanden Berg (1992ApJS...81..163B) and by a differential comparison of the color-magnitude diagram with that of Pal 5 is 12+/-2Gyr.
- ID:
- ivo://CDS.VizieR/J/PASP/104/1063
- Title:
- BV Color-Magnitude Diagram for NGC 1851
- Short Name:
- J/PASP/104/1063
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BV photometry is provided for 1,234 stars in the magnitude range 13-18 in an annulus between 5 and 20 arc seconds from the center of NGC 1851 and for 1,247 stars in the magnitude range 18-23 at a distance of more than 240 arc seconds from the center. For stars in the magnitude range 16-21, the errors in B-V increase with magnitude from 0.005 mag. to 0.022 mag. See the document file (walker.txt or walker.tex) by Nancy G. Roman for more details.
- ID:
- ivo://CDS.VizieR/J/AJ/139/2300
- Title:
- BVIc light curves of 3 type II Cepheids
- Short Name:
- J/AJ/139/2300
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Light curves in the B, V, and Ic passbands have been obtained for the type II Cepheids V154 in M3 and V42 and V84 in M5. Alternating cycle behavior, similar to that seen among RV Tauri variables, is confirmed for V84. Old and new observations, spanning more than a century, show that V154 has increased in period while V42 has decreased in period. V84, on the other hand, has shown large, erratic changes in period that do not appear to reflect the long-term evolution of V84 through the Hertzsprung-Russel diagram.
- ID:
- ivo://CDS.VizieR/J/MNRAS/372/1657
- Title:
- BVI(c) light curves of variables in M3
- Short Name:
- J/MNRAS/372/1657
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-series data on the variable stars of the galactic globular cluster Messier 3 (M3). We give BVI_C_ light curves for 226 RR Lyrae, 2 SX Phe and 1 W Vir type variables, along with estimated fundamental photometric parameters such as intensity and magnitude-averaged brightness and pulsation periods. In some cases, the periods we have found significantly differ from the previously published ones. This is the first published light curve and period determination for variable V266. The I-band light curve has not been observed previously for numerous (76) variables. Three new RR Lyrae variables have been discovered. Groups of RR Lyrae variables that belong to different evolutionary stages and have been separated previously on the basis of V data were found here for all colours and colour indices by cluster analysis. The I-band period-luminosity relation is also discussed. From the 66 modulated (Blazhko type) RR Lyrae stars we investigated, six are newly identified and two of them are first overtone pulsators. In the case of 13 RR Lyrae, the period of Blazhko cycle has been estimated for the first time. V252 is identified as a new RRd variable. Amplitude ratios of RRd stars have been investigated to search possible mode content changes. In contrast to previous publications no changes have been found. Problems with the sampling of the time-series of typical cluster variability surveys are demonstrated.
- ID:
- ivo://CDS.VizieR/J/ApJ/663/277
- Title:
- BVI of NGC 5466 red giants and blue stragglers
- Short Name:
- J/ApJ/663/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present wide-field BVI photometry for about 11500 stars in the low-metallicity cluster NGC 5466. We have detected the red giant branch bump for the first time, although it is at least 0.2mag fainter than expected relative to the turnoff. The number of red giants (relative to main-sequence turnoff stars) is in excellent agreement with stellar models from the Yonsei-Yale and Teramo groups, and slightly high compared to Victoria-Regina models. This adds to evidence that an abnormally large ratio of red giant to main-sequence stars is not correlated with cluster metallicity.
- ID:
- ivo://CDS.VizieR/J/ApJ/871/33
- Title:
- BVI photometric calatog of star clusters in NGC4589
- Short Name:
- J/ApJ/871/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC4589, a bright E2 merger-remnant galaxy, hosts the peculiar fast and faint calcium-rich supernova SNIb SN2005cz. The progenitor of Ca-rich SNeIb has been controversial: it could be (1) a young, massive star with 6-12M{sun} in a binary system, or (2) an old, low-mass star in a binary system that was kicked out from the galaxy center. Moreover, previous distance estimates for this galaxy have shown a large spread, ranging from 20 to 60Mpc. Thus, using archival Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) F435W, F555W, and F814W images, we search for star clusters in NGC4589 in order to help resolve these issues. We find a small population of young star clusters with 25<V<=27(-7.1<M_V_<-5.1)mag and age <1Gyr in the central region at R<0.5' (<3.8kpc), thus supporting the massive-star progenitor scenario for SN2005cz. In addition to young star clusters, we also find a large population of old globular clusters. In contrast to previous results in the literature, we find that the color distribution of the globular clusters is clearly bimodal. The turnover (Vega) magnitude in the V-band luminosity functions of the blue (metal-poor) globular clusters is determined to be V_0_(max)=24.40{+/-}0.10mag. We derive the total number of globular clusters, N_GC_=640{+/-}50, and the specific frequency, S_N_=1.7{+/-}0.2. Adopting a calibration for the metal-poor globular clusters, M_V_(max) =-7.66{+/-}0.14mag, we derive a distance to this galaxy: (m-M)_0_=32.06{+/-}0.10(ran){+/-}0.15(sys) (d=25.8{+/-}2.2Mpc).
