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Projeto Observacional para 2018A - SO2018A-025
Autor: Leandro Kerber
Título: An AO-Assisted Survey of RR Lyrae Stars in Fossil Bulge Globular Clusters
Resumo: Moderately metal-poor bluge globular clusters (GCs) ([Fe/H] <~ -1.0) with blue horizontal branches (BHB) are key pieces to trace the early Galactic formation stages. These characteristics suggest they are among the oldest GCs and/or objects with a large fraction of He enhanced stars. To disentagle this question it is mandatory to complete the census of RR Lyr stars within these clusters, particularly towards their innermost regions, since these stars provide excellent constraints to the distance and He abundance. However the severe field contamination, light extinction and crowding effect in bulge GCs have been a critical barrier to accomplish such goal. For this reason we propose na AO-assisted survey using SAM (VI filters) and image-substraction technique covering nine moderately metal-poor bulge GCs with BHB. These objects have been studied by our group using high resolution spectrocopy and/or analysis of deep colour-magnitude diagrams.