Metallicities of the exoplanet planet population. In blue are transiting planets, adapted from Thorngren et al. (2016) (dark blue). In red are directly imaged planets, with references listed below. Indicated with stars are the HR 8799 planets as measured in this work. The grey line indicates the fit by Thorngren et al. (2016). Notes: β Pic b (GRAVITY Collaboration 2020a); PDS 70 b (Wang et al. 2021a); 51 Eri b (Whiteford et al. 2023); VHS 1256 b (Hoch et al. 2022); HIP 65426 b (Petrus et al. 2021); κ And b (Bonnefoy et al. 2014; Wilcomb et al. 2020); YSES 1 b (Zhang et al. 2021) AB Pic b (Palma-Bifani et al. 2023); AF Lep b (Zhang et al. 2023); GJ 504 b (Bonnefoy et al. 2018); HD 95086 b (Desgrange et al. 2022); Ross 458 c (Burgasser et al. 2010); DH Tau b (Patience et al. 2012); HN Peg b (Leggett et al. 2008; Suárez et al. 2021); CT Cha b (Schmidt et al. 2008); GQ Lup b (Demars et al. 2023).