Evidence for Non-Homogeneity in the Metal Abundances of Stars in Globular Clusters

1978 ◽  
pp. 167-168
Author(s):  
Robert P. Kraft
Keyword(s):  
Globular Clusters ◽  
Metal Abundances

Recent Advances in High Dispersion Spectroscopy of Globular Cluster Stars

1988 ◽  
Vol 132 ◽  
pp. 525-530
Author(s):  
Raffaele G. Gratton
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
High Dispersion ◽  
Photographic Material ◽  
Recent Advances ◽  
Metal Abundances ◽  
Ccd Detectors ◽  
Major Progress

The use CCD detectors has allowed a major progress in abundance derivations for globular cluster stars in the last years. Abundances deduced from high dispersion spectra now correlates well with other abundance indicators. I discuss some problems concerning the derivation of accurate metal abundances for globular clusters using high dispersion spectra from both the old photographic and the most recent CCD data. The discrepant low abundances found by Cohen (1980), from photographic material for M71 giants, are found to be due to the use of too high microturbulences.

scholarly journals The Chemical Abundances of the Halo Clusters of the Galaxy

1978 ◽  
Vol 80 ◽  
pp. 177-182
Author(s):  
R. Canterna ◽  
R. A. Schommer
Keyword(s):  
Globular Clusters ◽  
Broad Band ◽  
Mean Value ◽  
Red Giants ◽  
Galactocentric Distance ◽  
Chemical Abundances ◽  
Dwarf Spheroidal Galaxies ◽  
The Galaxy ◽  
Ursa Minor ◽  
Metal Abundances

Photometric metal abundances of individual red giants in eight extremely distant halo globular clusters and the Draco and Ursa Minor dwarf spheroidal galaxies have been obtained using the Washington broad-band system, C, M, T1, T2(Canterna 1976). Observations were made at the KPNO 2.1-m and CTIO 1.5-m telescopes. In Table I we list for each system the mean value of [Fe/H], the number of stars observed in each system, n, the Galactocentric distance, RGC, the intrinsic color of the giant branch at the level of the horizontal branch (HB), (B-V)o,g, and the fraction of HB stars bluer than the RR Lyrae gap, fB. Sources for unpublished color-magnitude diagram (CMD) data are: Pal 11 (Canterna and Schommer), Pal 12 (Canterna and Harris), and Ursa Minor (Schommer, Olszewski and Kunkel).

Metal abundances from Washington photometry of globular clusters in NGC 5128

1992 ◽  
Vol 104 ◽  
pp. 613 ◽  
Author(s):  
Gretchen L. H. Harris ◽  
Doug Geisler ◽  
Hugh C. Harris ◽  
James E. Hesser
Keyword(s):  
Globular Clusters ◽  
Metal Abundances

Metal abundances for a large sample of globular clusters in M87

1993 ◽  
Vol 106 ◽  
pp. 493 ◽  
Author(s):  
Myung G. Lee ◽  
Doug Geisler
Keyword(s):  
Globular Clusters ◽  
Large Sample ◽  
Metal Abundances

Metal abundances of RR Lyrae stars in globular clusters

1982 ◽  
Vol 261 ◽  
pp. 576 ◽  
Author(s):  
H. A. Smith ◽  
G. J. Perkins
Keyword(s):  
Globular Clusters ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Metal Abundances ◽  
Lyrae Stars

scholarly journals J-PLUS: A wide-field multi-band study of the M 15 globular cluster

2019 ◽  
Vol 622 ◽  
pp. A179 ◽  
Author(s):  
Charles Bonatto ◽  
Ana L. Chies-Santos ◽  
Paula R. T. Coelho ◽  
Jesús Varela ◽  
Søren S. Larsen ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Broad Band ◽  
Asymptotic Giant Branch ◽  
Spectral Energy ◽  
Wide Field ◽  
Stellar Photometry ◽  
Spatial Coverage ◽  
Metal Abundances ◽  
Red Giant ◽  
Multi Band

Context. As a consequence of internal and external dynamical processes, Galactic globular clusters (GCs) have properties that vary radially. Wide-field observations covering the entire projected area of GCs out to their tidal radii (rtidal) can therefore give crucial information on these important relics of the Milky Way formation era. Aims. The Javalambre Photometric Local Universe Survey (J-PLUS) provides wide field-of-view (2 deg2) images in 12 narrow, intermediate and broad-band filters optimized for stellar photometry. Here we have applied J-PLUS data for the first time for the study of Galactic GCs using science verification data obtained for the very metal-poor ([Fe/H] ≈−2.3) GC M 15 located at ~10 kpc from the Sun. Previous studies based on spectroscopy found evidence of multiple stellar populations (MPs) through their different abundances of C, N, O, and Na. Our J-PLUS data provide low-resolution spectral energy distributions covering the near-UV to the near-IR, allowing us to instead search for MPs based on pseudo-spectral fitting diagnostics. Methods. We have built and discussed the stellar radial density profile (RDP) and surface brightness profiles (SBPs) reaching up to rtidal. Since J-PLUS FoV is larger than M 15’s rtidal, the field contamination can be properly taken into account. We also demonstrated the power of J-PLUS unique filter system by showing colour-magnitude diagrams (CMDs) using different filter combinations and for different cluster regions. Results. J-PLUS photometric quality and depth are good enough to reach the upper end of M 15’s main-sequence. CMDs based on the colours (u − z) and (J0378 − J0861) are found to be particularly useful to search for splits in the sequences formed by the upper red giant branch (RGB) and asymptotic giant branch (AGB) stars. We interpret these split sequences as evidence for the presence of MPs. Furthermore, we show that the (u − z) × (J0378 − g) colour–colour diagram allows us to distinguish clearly between field and M 15 stars, which is important to minimize the sample contamination. Conclusions. The J-PLUS filter combinations (u − z) and (J0378 − J0861), which are sensitive to metal abundances, are able to distinguish different sequences in the upper RGB and AGB regions of the CMD of M 15, showing the feasibility of identifying MPs without the need of spectroscopy. This demonstrates that the J-PLUS survey will have sufficient spatial coverage and spectral resolution to perform a large statistical study of GCs through multi-band photometry in the coming years.

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