Frontiers in Astronomy and Space Sciences, Vol 6 (2019) Front.Astron.Space Sci. Front.Astron.Space Sci., 2019, 6, pp.24. ⟨10.3389/fspas.2019.00024⟩ Frontiers in astronomy and space sciences 6, 24 (2019). doi:10.3389/fspas.2019.00024 Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual) Universidade de São Paulo (USP) instacron:USP Frontiers in Astronomy and Space Sciences, 6, pp. 1-19 Frontiers in Astronomy and Space Sciences, 6, 1-19 Frontiers in Astronomy and Space Sciences, 6