Accurate radial velocity and metallicity of the Large Magellanic Cloud old globular clusters NGC 1928 and NGC 1939
| Autor: | M. S. Angelo, B. Emptage, Andrés E. Piatti, Narae Hwang, Andrew A. Cole |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Physics
010308 nuclear & particles physics Metallicity Otras Ciencias Naturales y Exactas purl.org/becyt/ford/1.7 [https] FOS: Physical sciences Astronomy and Astrophysics Astrophysics Astrophysics - Astrophysics of Galaxies 01 natural sciences Spectral line Galaxy purl.org/becyt/ford/1 [https] Radial velocity Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Globular cluster 0103 physical sciences Cluster (physics) Spectroscopy Large Magellanic Cloud STAR CLUSTERS: GENERAL [GALAXIES] 010303 astronomy & astrophysics CIENCIAS NATURALES Y EXACTAS INDIVIDUAL: LMC [GALAXIES] |
| Zdroj: | CONICET Digital (CONICET) Consejo Nacional de Investigaciones Científicas y Técnicas instacron:CONICET |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | We present results obtained from spectroscopic observations of red giants located in the fields of the Large Magellanic Cloud (LMC) globular clusters (GCs) NGC 1928 and NGC 1939. We used the GMOS and AAOmega+2dF spectrographs to obtain spectra centred on the CaII triplet, from which we derived individual radial velocities (RVs) and metallicities. From cluster members we derived mean RVs of RV_NGC1928=249.58+-4.65 km/s and RV_NGC939=258.85+-2.08 km/s, and mean metallicities of [Fe/H]_NGC1928=-1.30+-0.15 dex and [Fe/H]_NGC1939=-2.00+-0.15 dex. We found that both GCs have RVs and positions consistent with being part of the LMC disc, so that we rule out any possible origin but that in the same galaxy. By computing the best solution of a disc that fully contains each GC, we obtained circular velocities for the 15 known LMC GCs. We found that 11/15 of the GCs share the LMC rotation derived from $HST$ and $Gaia$ DR2 proper motions. This outcome reveals that the LMC disc existed since the very early epoch of the galaxy formation and experienced the steep relatively fast chemical enrichment shown by its GC metallicities. The four remaining GCs turned out to have circular velocities not compatible with an in situ cluster formation, but rather with being stripped from the SMC. Comment: 10 pages, 9 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|