Comparisons between SSM evolutionary tracks computed adopting the different labelled boundary conditions, namely a grey atmosphere plus the T(τ) relationship by Krishna Swamy (1966) (KS66, dotted line) and the non-grey atmospheres by Brott & Hauschildt (2005) (BH05, solid line) and Castelli & Kurucz (2003) (CK03, dashed line) connected to the interior at τ_ph = 10. The symbol  ⊙  marks the position of the Sun.