5σ detection limits in L′ band for the LMIRCam data of HR 8799 expressed in contrast (left) and in planet mass (right), with the four planets shown (filled circles in the left panel and gray areas in the right panel). The positions of a putative fifth planet in resonance 3:1 and 2:1 with planet e according to the models of Goździewski & Migaszewski (2014) are also indicated (assuming a face-on and circular orbit). For the right plot, the detection limits are derived for an age of 30 Myr from the “hot-start” COND model (Baraffe et al. 2003) coupled to the atmosphere model BT-Settl (Allard et al. 2012) and the “warm-start” evolutionary+atmosphere model of Spiegel & Burrows (2012) for an initial entropy of 9 k_B/baryon (see text). The range of masses for HR 8799 bcde is delimited by the predictions of the two evolutionary models assumed for deriving the detection limits (lower limit: BT-Settl+COND; upper limit: SB12 with initial entropy of 9 k_B/baryon). The range of physical separations for the planets is computed using the errors on the planet separation and the star distance.