FIG. 8.

Evolution of the flux received by planets that are at the inner edge of the theoretical HZ at 5 Gyr for different stellar masses (blue: 0.1 M_⊙, green: 0.5 M_⊙, red: 0.7 M_⊙, cyan: 1.0 M_⊙). The vertical axis is the bolometric flux normalized to the runaway greenhouse flux; the region shaded in pink corresponds to planets that are interior to the RG limit. The dashed vertical line corresponds to the 10 Myr formation time we assume in our model. The horizontal lines at the bottom of the plot indicate the times during which planets are in a runaway greenhouse. Planets around late-type M dwarfs experience a single long runaway prior to the star's arrival on the MS. Planets around G dwarfs experience an initial runaway phase if they form in the first ∼2 Myr as well as a late phase due to the star's brightening during the MS. Planets around K dwarfs (0.6 M_⊙≲M_★≲0.9 M_⊙) experience three runaway episodes, due to the temporary increase in the star's luminosity prior to the arrival on the MS between ∼50 and ∼100 Myr. This is due to the fact that these stars switch from convective to radiative energy transport at the end of their Hayashi contraction phase. See text for a discussion.