- ID:
- ivo://CDS.VizieR/J/AJ/122/3219
- Title:
- M3 and M13 CCD BV photometry
- Short Name:
- J/AJ/122/3219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-precision V, B-V color-magnitude diagrams (CMDs) for the classic second-parameter globular clusters M3 and M13 from wide-field, deep CCD photometry. The data for the two clusters were obtained during the same photometric nights with the same instrument, allowing us to determine accurate relative ages. Based on a differential comparison of the CMDs using the {Delta}(B-V) method, an age difference of 1.7+/-0.7Gyr is obtained between these two clusters. We compare this result with our updated horizontal-branch (HB) population models, which confirm that the observed age difference can produce the difference in HB morphology between the clusters. This provides further evidence that age is the dominant second parameter that influences HB morphology.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/891/85
- Title:
- Manganese abundances in GC & dSph galaxies
- Short Name:
- J/ApJ/891/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Manganese abundances are sensitive probes of the progenitors of TypeIa supernovae (SNe Ia). In this work, we present a catalog of manganese abundances in dwarf spheroidal satellites of the Milky Way, measured using medium-resolution spectroscopy. Using a simple chemical evolution model, we infer the manganese yield of SNe Ia in the Sculptor dwarf spheroidal galaxy (dSph) and compare to theoretical yields. The sub-solar yield from SNIa ([Mn/Fe]_Ia_=-0.30_-0.03_^+0.03^ at [Fe/H]=-1.5dex, with negligible dependence on metallicity) implies that sub-Chandrasekhar-mass (sub-MCh) white dwarf progenitors are the dominant channel of SNe Ia at early times in this galaxy, although some fraction (>~20%) of M_Ch_ Type Ia or Type Iax SNe are still needed to produce the observed yield. First-order corrections for deviations from local thermodynamic equilibrium increase the inferred [Mn/Fe]_Ia_ by as much as ~0.3dex. However, our results also suggest that the nucleosynthetic source of SNe Ia may depend on environment. In particular, we find that dSphs with extended star formation histories (Leo I, Fornax dSphs) appear to have higher [Mn/Fe] at a given metallicity than galaxies with early bursts of star formation (Sculptor dSph), suggesting that M_Ch_ progenitors may become the dominant channel of SNe Ia at later times in a galaxy's chemical evolution.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/90
- Title:
- Mass segregation effect of X-ray sources in GCs. II.
- Short Name:
- J/ApJ/883/90
- Date:
- 06 Dec 2021 13:23:40
- Publisher:
- CDS
- Description:
- Using archival Chandra observations with a total effective exposure of 734ks, we derive an updated catalog of point sources in the massive globular cluster (GC) Terzan 5. Our catalog covers an area of 58.1arcmin^2^ (R<=4.3') with 489 X-ray sources, and more than 75% of these sources are first detected in this cluster. We find significant dips in the radial distribution profiles of X-ray sources in Terzan 5, with the projected distance and width of the distribution dips for bright (L_X_>~9.5x10^30^erg/s) X-ray sources larger than those of the faint (L_X_<~9.5x10^30^erg/s) sources. By fitting the radial distribution of the X-ray sources with a "generalized King model," we estimated an average mass of 1.48+/-0.11 and 1.27+/-0.13M_{sun}_ for the bright and faint X-ray sources, respectively. These results are in agreement with that observed in 47 Tuc, which may suggest a universal mass segregation effect for X-ray sources in GCs. Compared with 47Tuc, we show that the two-body relaxation timescale of Terzan 5 is much smaller, but its dynamical age is significantly younger than 47 Tuc. These features suggest that the evolution of Terzan 5 is not purely driven by two-body relaxation, and the tidal stripping effect also plays an important role in accelerating the dynamical evolution of this cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/903/73
- Title:
- MAVERIC survey: deep VLA imaging of 25 GCs
- Short Name:
- J/ApJ/903/73
- Date:
- 17 Feb 2022 13:24:49
- Publisher:
- CDS
- Description:
- The MAVERIC survey is the first deep radio continuum imaging survey of Milky Way globular clusters, with a central goal of finding and classifying accreting compact binaries, including stellar-mass black holes. Here we present radio source catalogs for 25 clusters with ultra-deep Karl G. Jansky Very Large Array observations. The median observing time was 10 hr per cluster, resulting in typical rms sensitivities of 2.3 and 2.1{mu}Jy per beam at central frequencies of 5.0 and 7.2GHz, respectively. We detect nearly 1300 sources in our survey at 5{sigma}, and while many of these are likely to be background sources, we also find strong evidence for an excess of radio sources in some clusters. The radio spectral index distribution of sources in the cluster cores differs from the background, and shows a bimodal distribution. We tentatively classify the steep-spectrum sources (those much brighter at 5.0GHz) as millisecond pulsars and the flat-spectrum sources as compact or other kinds of binaries. These provisional classifications will be solidified with the future addition of X-ray and optical data. The outer regions of our images represent a deep, relatively wide-field (~0.4deg^2^) and high-resolution C band background survey, and we present source counts calculated for this area. We also release radio continuum images for these 25 clusters to the community.
415. M 68 BVRI photometry
- ID:
- ivo://CDS.VizieR/J/AJ/99/1831
- Title:
- M 68 BVRI photometry
- Short Name:
- J/AJ/99/1831
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BVRI photometry of the low metallicity globular cluster M68 (NGC 4590) observed with a CCD camera and the 2.2m telescope at ESO/La Silla, and have compared our BV color-magnitude diagrams with the observational results of a previous research. At magnitudes V<22, our BV results, obtained using the INVENTORY code, are in very close agreement with those of the other authors who used DAOPHOT in their reductions. At fainter levels, selection effects appear to affect INVENTORY more than DAOPHOT. We find that V_TO-HB_=3.42+/-0.10, in accord with values found for other clusters. The comparison between our four-color observations and the theoretical isochrones consistently yield a cluster age of 13Gyr with a likely external uncertainty of 2 or 3Gyr. Our derived values for the interstellar reddening at longer wavelengths are generally in agreement (+/-0.02mag) with what would be expected assuming E(B-V)=0.07mag and (m-M)_V_=15.25.
- ID:
- ivo://CDS.VizieR/J/AJ/141/62
- Title:
- M5 chemical abundances for evolved stars
- Short Name:
- J/AJ/141/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present analysis of high-resolution spectra of a sample of stars in the globular cluster M5 (NGC 5904). The sample includes stars from the red giant branch (RGB; seven stars), the red horizontal branch (two stars), and the asymptotic giant branch (AGB; eight stars), with effective temperatures ranging from 4000K to 6100K. Spectra were obtained with the HIRES spectrometer on the Keck I telescope, with a wavelength coverage from 3700{AA} to 7950{AA} for the HB and AGB sample, and 5300{AA} to 7600{AA} for the majority of the RGB sample.
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/2621
- Title:
- M4 Core Project with HST. Radial velocities
- Short Name:
- J/MNRAS/454/2621
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed study of the internal kinematics of the Galactic globular cluster M 4 (NGC 6121), by deriving the radial velocities from 7250 spectra for 2771 stars distributed from the upper part of the red giant branch down to the main sequence. We describe new approaches to determine the wavelength solution from day-time calibrations and to determine the radial velocity drifts that can occur between calibration and science observations when observing with the GIRAFFE spectrograph at Very Large Telescope. Two techniques to determine the radial velocity are compared, after a qualitative description of their advantages with respect to other commonly used algorithm, and a new approach to remove the sky contribution from the spectra obtained with fibre-fed spectrograph and further improve the radial velocity precision is presented. The average radial velocity of the cluster is <v>=71.08+/-0.08km/s with an average dispersion of {mu}_vc_=3.97km/s. Using the same data set and the same statistical approach of previous analyses, 20 additional binary candidates are found, for a total of 87 candidates. A new determination of the internal radial velocity dispersion as a function of cluster distance is presented, resulting in a dispersion of 4.5km/s within 2-arcmin from the centre of cluster and steadily decreasing outward. We statistically confirm the small amplitude of the cluster rotation, as suggested in the past by several authors. This new analysis represents a significant improvement with respect to previous results in literature and provides a fundamental observational input for the modelling of the cluster dynamics.
- ID:
- ivo://CDS.VizieR/J/AJ/132/2187
- Title:
- MCT1 photometry of NGC 5128 globular clusters
- Short Name:
- J/AJ/132/2187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first results from an imaging program with the ACS on the Hubble Space Telescope designed to measure the structural characteristics of a wide range of globular clusters in NGC 5128, the nearest giant elliptical galaxy. From 12 ACS WFC fields we have measured a total of 62 previously known globular clusters and have discovered 69 new high-probability cluster candidates not found in any previous work. We present magnitudes and color indices for all of these, along with rough measurements of their effective diameters and ellipticities.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A161
- Title:
- Measured atmospheric parameters of NGC6397 stars
- Short Name:
- J/A+A/635/A161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent work has used spectra of ~5000 stars in NGC 6397 that were extracted from a MUSE mosaic to determine the atmospheric parameters for these stars by fitting the spectra against the Goettingen Spectral Library. A significant change in metallicity between the turn off and the red giant branch was found and was discussed as a possible manifestation of predicted effects of atomic diffusion. However, the small amplitude of the effect and inconsistency with earlier measurements call for more attention before this result is interpreted. Systematic effects due to the interpolation or to the synthetic spectra cannot be ruled out at this level of precision. We reanalyze the data with : the ELODIE and MILES reference libraries in order to assess the robustness of the result. These empirical libraries have a finer metallicity coverage down to approximately the cluster metallicity turn-off. Methods. We used the ULySS full-spectrum fitting package, together with the library interpolators to remeasure the three atmospheric parameters effective temperature, surface gravity, and [Fe/H] metallicity. We find a very low [Fe/H] dispersion along the isochrone (0.07dex), consistent with our error estimate (0.05dex). However, the [Fe/H] trend is not reproducible. This shows that the data have the potential to reveal patterns of the magnitude of the expected physical effects, but the analysis methods need to be refined to cull systematic effects that currently dominate the patterns.
- ID:
- ivo://CDS.VizieR/J/ApJ/808/19
- Title:
- Megasecond Chandra XVP obs. of NGC3115. II.
- Short Name:
- J/ApJ/808/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out an in-depth study of low-mass X-ray binaries (LMXBs) detected in the nearby lenticular galaxy NGC 3115 using the Megasecond Chandra X-ray Visionary Project observation (total exposure time 1.1Ms). In total we found 136 candidate LMXBs in the field and 49 in globular clusters (GCs) above 2{sigma} detection, with 0.3-8keV luminosity L_X_~10^36^-10^39^erg/s. Other than 13 transient candidates, the sources overall have less long-term variability at higher luminosity, at least at L_X_>~2x10^37^erg/s. In order to identify the nature and spectral state of our sources, we compared their collective spectral properties based on single-component models (a simple power law or a multicolor disk) with the spectral evolution seen in representative Galactic LMXBs. We found that in the L_X_ versus photon index {Gamma}_PL_ and L_X_versus disk temperature kT_MCD_ plots, most of our sources fall on a narrow track in which the spectral shape hardens with increasing luminosity below L_X_~7x10^37^erg/s, but is relatively constant ({Gamma}_PL_~1.5 or kT_MCD_~1.5keV) above this luminosity, which is similar to the spectral evolution of Galactic neutron star (NS) LMXBs in the soft state in the Chandra bandpass. Therefore, we identified the track as the NS LMXB soft-state track and suggested sources with L_X_<~7x10^37^erg/s as atolls in the soft state and those with L_X_>~7x10^37^erg/s as Z sources. Ten other sources (five are transients) displayed significantly softer spectra and are probably black hole X-ray binaries in the thermal state. One of them (persistent) is in a metal-poor GC.
