| Full text | |
| Author(s): Show less - |
Barbuy, B.
[1]
;
Cantelli, E.
[1]
;
Muniz, L.
[1]
;
Souza, S. O.
[1]
;
Chiappini, C.
[2]
;
Hirschi, R.
[3, 4]
;
Cescutti, G.
[5, 6]
;
Pignatari, M.
[7, 8, 9]
;
Ortolani, S.
[10, 11]
;
Kerber, L.
[12]
;
Maia, F. F. S.
[13]
;
Bica, E.
[14]
;
Depagne, E.
[15]
Total Authors: 13
|
| Affiliation: Show less - | [1] Univ Sao Paulo, IAG, Rua Matao 1226, Cidade Univ, BR-05508900 Sao Paulo - Brazil
[2] Astrophys Inst Potsdam, Sternwarte 16, D-14482 Potsdam - Germany
[3] Keele Univ, Astrophys Grp, Keele ST5 5BG, Staffs - England
[4] Univ Tokyo, Kavli Inst Phys & Math Universe WPI, 5-1-5 Kashiwanoha, Kashiwa, Chiba 2778583 - Japan
[5] INAF, Osservatorio Astron Trieste, Via GB Tiepolo 11, I-34143 Trieste - Italy
[6] Ist Fundamental Phys Universe, IFPU, Via Beirut 2, I-34151 Trieste - Italy
[7] Univ Hull, EA Milne Ctr Astrophys, Dept Phys & Math, Kingston Upon Hull HU6 7RX, N Humberside - England
[8] Hungarian Acad Sci, Konkoly Observ, Res Ctr Astron & Earth Sci, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest - Hungary
[9] Joint Inst Nucl Astrophys, Ctr Evolut Elements, New York, NY - USA
[10] Univ Padua, Dipartimento Astron, Vicolo Osservatorio 2, I-35122 Padua - Italy
[11] INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua - Italy
[12] Univ Estadual Santa Cruz, Dept Ciencias Exatas & Tecnol, Rodovia Jorge Amado Km 16, BR-45662900 Ilheus, BA - Brazil
[13] Univ Fed Rio de Janeiro, Inst Fis, Av Athos da Silveira Ramos 149, BR-21941972 Rio De Janeiro - Brazil
[14] Univ Fed Rio Grande do Sul, Dept Astron, CP 15051, BR-91501970 Porto Alegre, RS - Brazil
[15] South African Astron Observ SAAO, POB 9, ZA-7935 Observatory - South Africa
Total Affiliations: 15
|
| Document type: | Journal article |
| Source: | Astronomy & Astrophysics; v. 654, OCT 5 2021. |
| Web of Science Citations: | 1 |
| Abstract | |
Context. NGC 6522 is a moderately metal-poor bulge globular cluster ({[}Fe/H] similar to-1.0), and it is a well-studied representative among a number of moderately metal-poor blue horizontal branch clusters located in the bulge. The NGC 6522 abundance pattern can give hints on the earliest chemical enrichment in the central Galaxy. Aims. The aim of this study is to derive abundances of the light elements C and N; alpha elements O, Mg, Si, Ca, and Ti; odd-Z elements Na and Al; neutron-capture elements Y, Zr, Ba, La, and Nd; and the r-process element Eu. We verify if there are first- and second-generation stars: we find clear evidence of Na-Al, Na-N, and Mg-Al correlations, while we cannot identify the Na-O anti-correlation from our data. Methods. High-resolution spectra of six red giants in the bulge globular cluster NGC 6522 were obtained at the 8m VLT UT2-Kueyen telescope with both the UVES and GIRAFFE spectrographs in FLAMES+UVES configuration. In light of Gaia data, it turned out that two of them are non-members, but these were also analysed. Spectroscopic parameters were derived through the excitation and ionisation equilibrium of Fe I and Fe II lines from UVES spectra. The abundances were obtained with spectrum synthesis. Comparisons of abundances derived from UVES and GIRAFFE spectra were carried out. Results. The present analysis combined with previous UVES results gives a mean radial velocity of v(r)(hel) r = -15.62 +/- 7.7 km s(-1) and a metallicity of {[}Fe/H] = 1.05 +/- 0.20 for NGC 6522. Mean abundances of alpha elements for the present four member stars are enhanced with {[}O/Fe] = +0.38, {[}Mg/Fe] = approximate to+0.28, {[}Si/Fe] approximate to +0.19; and {[}Ca/Fe] approximate to +0.13, together with the iron-peak element {[}Ti/Fe] approximate to +0.13, and the r-process element {[}Eu/Fe] = +0.40. The neutron-capture elements Y, Zr, Ba, and La show enhancements in the +0.08 < {[}Y/Fe] < +0.90, 0.11 < {[}Zr/Fe] < +0.50, 0.00 < {[}Ba/Fe] < +0.63, 0.00 < {[}La/Fe] < +0.45, and 0.10 < {[}Nd/Fe] < +0.70 ranges. We also discuss the spread in heavy-element abundances. (AU) | |
| FAPESP's process: | 18/22044-3 - Bulge globular clusters: relics of the early formation of the galaxy |
| Grantee: | Stefano Oliveira de Souza |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |