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Projeto Observacional para 2018A - SO2018A-016

Autor: Augusto Damineli Neto
Instituição: IAG
e-mail: damineli@astro.iag.usp.br

Marcelo Soares Rubinho

Título: The evolved stellar population of Westerlund 1 super-starcluster

Resumo: Westerlund 1 is potentially the most massive (>5x 10^4) young cluster in the Galaxy. Recently we measured accurately its reddening (AV=11.26) and distance (4.35 kpc) and we are ready to study its luminous members. However, although the existing photometry enables studies of general properties, it is not reliable to put the stars in the HR diagram and to solve the pending contradiction defined by the presence of 4 Red Supergiants (which indicates and age >6 Gyr) and the 24 Wolf-Rayet stars (which indicate age < 5 Gyr). The study of evolutionary phase of the Yellow Hypergiants, if they are moving towards the Red Supergiant Brunch or back to the blue side of the HRD also demands accurate photometry. Among the problems of previous photometric studies we mention: saturation of bright stars, non-coeval photometry in the optical ad NIR, FOV too small, spatially variable reddening. Most of those problems could be overcome by doing simultaneous optical and NIR photometry at SOAR, using Goodman and Spartan cameras in a single night.