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dc.contributor.authorBonatto, Charles Josept_BR
dc.contributor.authorCampos, Fabíolapt_BR
dc.contributor.authorKepler, Souza Oliveirapt_BR
dc.date.accessioned2014-04-03T01:51:51Zpt_BR
dc.date.issued2013pt_BR
dc.identifier.issn0035-8711pt_BR
dc.identifier.urihttp://hdl.handle.net/10183/90323pt_BR
dc.description.abstractWe build differential-reddening maps for 66 Galactic globular clusters (GCs) with archival Hubble Space Telescope WFC/ACS F606W and F814W photometry. Because of the different GC sizes (characterized by the half-light radius Rh) and distances to the Sun, the WFC/ACS field of view (200 arcsec × 200 arcsec) coverage (Robs) lies in the range 1 < ~ Robs/Rh < ~ 15 for about 85 per cent of the sample, with about 10 per cent covering only the inner (Robs < ~ Rh) parts.We divide the WFC/ACS field of view across each cluster in a regular cell grid and extract the stellar-density Hess diagram from each cell, shifting it in colour and magnitude along the reddening vector until matching the mean diagram. Thus, the maps correspond to the internal dispersion of the reddening around the mean. Depending on the number of available stars (i.e. probable members with adequate photometric errors), the angular resolution of the maps range from ≈7 arcsec × 7 arcsec to ≈20 arcsec × 20 arcsec. We detect spatially variable extinction in the 66 GCs studied, with mean values ranging from ‹ δE(B − V )› ≈ 0.018 (NGC 6981) up to ‹δE(B − V )› ≈ 0.16 (Palomar 2). Differential-reddening correction decreases the observed foreground reddening and the apparent distance modulus but, since they are related to the same value of E(B − V), the distance to the Sun is conserved. Fits to the mean-ridge lines of the highly extincted and photometrically scatteredGCPalomar 2 showthat age and metallicity also remain unchanged after the differential-reddening correction, but measurement uncertainties decrease because of the reduced scatter. The lack of systematic variations of ‹δE(B − V )› with both the foreground reddening and the sampled cluster area indicates that the main source of differential reddening is interstellar.en
dc.format.mimetypeapplication/pdfpt_BR
dc.language.isoengpt_BR
dc.relation.ispartofMonthly notices of the royal astronomical society. Oxford. Vol. 435, no. 1 (Oct. 2013), p. 263-272pt_BR
dc.rightsOpen Accessen
dc.subjectHalospt_BR
dc.subjectGlobular clusters: generalen
dc.subjectAglomerados estelares globularespt_BR
dc.titleMapping the differential reddening in globular clusterspt_BR
dc.typeArtigo de periódicopt_BR
dc.identifier.nrb000912381pt_BR
dc.type.originEstrangeiropt_BR


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