- ID:
- ivo://CDS.VizieR/J/A+A/564/L3
- Title:
- JHK photometry of NGC 3115 globular clusters
- Short Name:
- J/A+A/564/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combined new near-infrared VLT/HAWK-I data of the globular clusters (GCs) in the isolated edge-on S0 galaxy NGC 3115 with optical and spectroscopic ones taken from the literature, with the aim of analyzing the multiband GC color distributions. A recent study from the SLUGGS survey has shown that the GCs in this galaxy follow a bimodal distribution of CaII triplet indices. Thus, NGC3115 presents a critical example of a GC system with multiple, distinct, metallicity subpopulations, and this may argue against the "projection" scenario, which posits that the ubiquitous color bimodality mainly results from nonlinearities in the color- metallicity relations. Using optical, NIR, and spectroscopic data, we found strong and consistent evidence of index bimodality, which independently confirms the metallicity bimodality in NGC 3115 GCs. At the same time, we also found evidence for some color-color nonlinearity. Taken in the broader context of previous studies, the multicolor consistency of the GC bimodality in NGC 3115 suggests that in cases where GC systems exhibit clear differences between their optical and optical-NIR color distributions (as in some giant ellipticals), the apparent inconsistencies most likely result from nonlinearities in the color-metallicity relations.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/361/272
- Title:
- JHKs photometry of 4 Bulge globular clusters
- Short Name:
- J/MNRAS/361/272
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-quality near-infrared photometry of four bulge metal-rich globular clusters, namely: NGC 6304, NGC 6569, NGC 6637 and NGC 6638. By using the observed Colour-Magnitude Diagrams we derived a photometric estimates of the cluster reddening and distance. We performed a detailed analysis of the Red Giant Branch, presenting a complete description of morphologic parameters and evolutionary features (Bump and Tip). Photometric estimates of the cluster metallicity have been obtained by using the updated set of relations (published by our group) linking the metal abundance to a variety of near-Infrared indices measured along the Red Giant Branch. The detection of the Red Giant Branch Bump and the Tip is also presented and briefly discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/489/583
- Title:
- JHKs photometry of GLIMPSE-C02
- Short Name:
- J/A+A/489/583
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The estimated total number of Milky Way globulars is 160+/-20. The question of whether there are any more undiscovered globular clusters in the Milky Way is particularly relevant with advances in near and mid-IR instrumentation. This investigation is a part of a long-term project to search the inner Milky Way for hidden star clusters and to study them in detail. GLIMPSE-C02 (G02) is one of these objects, situated near the Galactic plane (l=14.129{deg}, b=-0.644{deg}). Our analysis is based on SOFI/NTT JHKs imaging and low resolution (R~1400) spectroscopy of three bright cluster red giants in the K atmospheric window. We derived the metal abundance by analysis of these spectra and from the slope of the RGB.
- ID:
- ivo://CDS.VizieR/J/MNRAS/370/1979
- Title:
- JHKs photometry of T2Cs in globular clusters
- Short Name:
- J/MNRAS/370/1979
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the result of our near-infrared observations (JHKs) for type II Cepheids (including possible RV Tau stars) in galactic globular clusters. We detected variations of 46 variables in 26 clusters (10 new discoveries in seven clusters) and present their light curves. Their periods range from 1.2d to over 80d. They show a well-defined period-luminosity relation at each wavelength. Two type II Cepheids in NGC 6441 also obey the relation if we assume the horizontal branch stars in NGC 6441 are as bright as those in metal-poor globular clusters in spite of the high metallicity of the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/133/99
- Title:
- JHKs surface brightness of Galactic globular.
- Short Name:
- J/AJ/133/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have mosaicked Two Micron All Sky Survey (2MASS) images to derive surface brightness profiles in J, H, and Ks for 104 Galactic globular clusters. We fit these with King profiles and show that the core radii are identical to within the errors for each of these IR colors and are identical to the core radii at V in essentially all cases. We derive integrated-light colors V-J, V-H, V-Ks, J-H, and J-Ks for these globular clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/150/176
- Title:
- JK photometry of 12 galactic globular clusters
- Short Name:
- J/AJ/150/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present wide field near-infrared (near-IR) photometry of 12 Galactic globular clusters, typically extending from the tip of the cluster red giant branch (RGB) to the main sequence turnoff. Using recent homogenous values of cluster distance, reddening and metallicity, the resulting photometry is directly compared to the predictions of several recent libraries of stellar evolutionary models. Of the sets of models investigated, Dartmouth and Victoria-Regina models best reproduce the observed RGB morphology, albeit with offsets in J-K_S_ color which vary in their significance in light of all sources of observational uncertainty. Therefore, we also present newly recalibrated relations between near-IR photometric indices describing the upper RGB versus cluster iron abundance as well as global metallicity. The influence of enhancements in alpha elements and helium are analyzed, and we find that the former affect the morphology of the upper RGB in accord with model predictions. Meanwhile, the empirical relations we derive are in good agreement with previous results, and minor discrepancies can likely be attributed to differences in the assumed cluster distances and reddenings. In addition, we present measurements of the horizontal branch (HB) and RGB bump magnitudes, finding a non-negligible dependence of the near-IR HB magnitude on cluster metallicity. Lastly, we discuss the influence of assumed cluster distances, reddenings and metallicities on our results, finding that our empirical relations are generally insensitive to these factors to within their uncertainties.
- ID:
- ivo://CDS.VizieR/J/AJ/119/2274
- Title:
- JK Photometry of globular clusters M15 & M56
- Short Name:
- J/AJ/119/2274
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared JKs-band photometry of the Galactic globular clusters M15 and, for the first time, M56 is presented. We estimate the reddening [E(B-V) = 0.18 {=/-} 0.08 mag] and distance modulus [(m - M)V = 15.43 {+/-} 0.30 mag] toward the poorly studied globular cluster M56. We combine our data with observations of other clusters from the literature (12 in total) to extend the [Fe/H] versus red giant branch (RGB) slope relation toward metal-poor clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A51
- Title:
- JK photometry of NGC 2808
- Short Name:
- J/A+A/586/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters are the oldest stellar systems in the Milky Way, and they probe the early epoch of the Galaxy formation. However, the uncertainties on their absolute age are still too large to soundly constrain how the Galactic structures have assembled. The aim of this work is to obtain an accurate estimate of the absolute age of the globular cluster NGC 2808 using deep IR data obtained with the multi-conjugate adaptive optics system operating at the Gemini South telescope (GeMS). This exquisite photometry, combined with that obtained in V and I-bands with HST, allowed us to detect the faint Main Sequence Knee feature in NGC 2808 colour magnitude diagram. The difference between this point and the main sequence turn-off is a good age estimator that provides ages with unprecedented accuracy.
- ID:
- ivo://CDS.VizieR/J/A+A/419/139
- Title:
- JK photometry on 5 Galactic globular clusters
- Short Name:
- J/A+A/419/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IR catalogs of the observed clusters are based on ground-based observations using the near-IR camera ARNICA@TNG equipped with a NICMOS-3 256x256 array detector. By using a magnification of 0.35"/px a total FoV of 1.5'x1.5' has been covered. The instrumental magnitudes have been calibrated into the Ferraro et al. (2000AJ....119.1282F) system. The catalogs for all the program clusters have been astrometrically corrected by using 2MASS catalogs, with an accuracy of <0.2arcsec.
- ID:
- ivo://CDS.VizieR/J/A+A/331/70
- Title:
- JKVI photometry of NGC 6553 stars
- Short Name:
- J/A+A/331/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- JK infrared photometry for the bulge globular cluster NGC 6553, combined with high resolution visual VI observations are presented and discussed in connection with the bulge metal rich population. The infrared data were taken with IRAC2 at ESO 2.2m telescope while the optical counterparts are from Hubble Space Telescope (HST). We find a mean magnitude for the horizontal branch of V_HB_=16.92, and K_HB_=12.42+/-0.01. Assuming a reddening of E(B-V)=0.7, the mean distance modulus is (m-M)_0_=13.6 giving an heliocentric distance of 5.2Kpc. This distance is slightly higher than that previously published by Ortolani et al. (1990A&A...236..362O, hereafter OBB90). The brightest giants have been detected at K~6.5 and (V-K)=13.10 transforming to M_K_=-7.34 and (V-K)_0_=11.20, which are exceptionally high values for a globular cluster. The metallicity has been found to be consistent with previous values and an average of [Fe/H]=-0.22+/-0.05 has been adopted. The helium abundance estimated via the R' method yields Y_p_~0.28+/-0.03.
