Stromgren photometry in globular clusters: M55 & M22

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dc.contributor.authorRichter, P
dc.contributor.authorHilker, M
dc.contributor.authorRichtler, T
dc.date.accessioned2025-01-21T01:31:51Z
dc.date.available2025-01-21T01:31:51Z
dc.date.issued1999
dc.description.abstractWe present Stromgren CCD photometry for the two galactic globular clusters M55 (NGC6809) and M22 (NGC6656).
dc.description.abstractWe find average Stromgren metallicities of -1.71+/-0.04 dex for M55 and -1.62 +/- 0.08 dex for M22. The determination of metal abundances in cluster giants with the Stromgren mi index in comparison with spectroscopic data from Briley et al. (1993) and Norris & Freeman (1982, 1983) shows that:M55 and M22 have different distributions of cyanogen strengths. In M55, no CN abundance variations are visible among the giant-branch stars. In striking contrast, a large dispersion of cyanogen strengths is seen in M22. For M22 we find patchily distributed variations in the foreground reddening of Delta E(B - V) approximate to 0.07, which explain the colour dispersion among the giant-branch stars. There is no evidence for a spread in iron within M22 since the variations in mi are dominated by the large range in CN abundances, as already found by Anthony-Twarog et al. (1995). The difference between M55 and M22 may resemble the difference in integral CN band strength between M31 globular clusters and the galactic system.
dc.description.abstractThe colour-magnitude diagram of M55 shows the presence of a population of 56 blue-straggler stars that are more centrally concentrated than the red giant-branch stars.
dc.fuente.origenWOS
dc.identifier.issn1432-0746
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/97156
dc.identifier.wosidWOS:000083389900016
dc.issue.numero2
dc.language.isoen
dc.pagina.final484
dc.pagina.inicio476
dc.revistaAstronomy & astrophysics
dc.rightsacceso restringido
dc.subjectGalaxy : globular clusters : individual : M22
dc.subjectGalaxy : globular clusters : individual : M55
dc.subjectstars : abundances
dc.subjectstars : blue stragglers
dc.titleStromgren photometry in globular clusters: M55 & M22
dc.typeartículo
dc.volumen350
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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