Marois, C. et al. Direct imaging of multiple planets orbiting the star HR 8799. Science 322, 1348 (2008).

Article 
ADS 

Google Scholar
 

Zurlo, A. et al. Orbital and dynamical analysis of the system around HR 8799. New astrometric epochs from VLT/SPHERE and LBT/LUCI. Astron. Astrophys. 666, A133 (2022).

Article 

Google Scholar
 

Ida, S. & Lin, D. N. C. Toward a deterministic model of planetary formation. I. A desert in the mass and semimajor axis distributions of extrasolar planets. Astrophys. J. 604, 388–413 (2004).

Article 
ADS 

Google Scholar
 

Nasedkin, E. et al. Four-of-a-kind? Comprehensive atmospheric characterisation of the HR 8799 planets with VLTI/GRAVITY. Astron. Astrophys. 687, A298 (2024).

Article 

Google Scholar
 

Wang, J. Early accretion of large amounts of solids for directly imaged exoplanets. Astrophys. J. 981, 138 (2025).

Article 
ADS 

Google Scholar
 

Öberg, K. I., Murray-Clay, R. & Bergin, E. A. The effects of snowlines on C/O in planetary atmospheres. Astrophys. J. Lett. 743, L16 (2011).

Article 
ADS 

Google Scholar
 

Mordasini, C., van Boekel, R., Mollière, P., Henning, T. & Benneke, B. The imprint of exoplanet formation history on observable present-day spectra of hot Jupiters. Astrophys. J. 832, 41 (2016).

Article 
ADS 

Google Scholar
 

Mollière, P. et al. Interpreting the atmospheric composition of exoplanets: sensitivity to planet formation assumptions. Astrophys. J. 934, 74 (2022).

Article 
ADS 

Google Scholar
 

Konopacky, Q. M., Barman, T. S., Macintosh, B. A. & Marois, C. Detection of carbon monoxide and water absorption lines in an exoplanet atmosphere. Science 339, 1398–1401 (2013).

Article 
ADS 

Google Scholar
 

Xuan, J. W. et al. Are these planets or brown dwarfs? Broadly solar compositions from high-resolution atmospheric retrievals of ~10–30 MJup companions. Astrophys. J. 970, 71 (2024).

Article 
ADS 

Google Scholar
 

Ruffio, J.-B. et al. JWST-TST high contrast: achieving direct spectroscopy of faint substellar companions next to bright stars with the NIRSpec integral field unit. Astron. J. 168, 73 (2024).

Article 
ADS 

Google Scholar
 

Böker, T. et al. The near-infrared spectrograph (NIRSpec) on the James Webb Space Telescope. III. Integral-field spectroscopy. Astron. Astrophys. 661, A82 (2022).

Article 

Google Scholar
 

Balmer, W. O. et al. JWST-TST high contrast: living on the wedge, or, NIRCam bar coronagraphy reveals CO2 in the HR 8799 and 51 Eri exoplanets’ atmospheres. Astron. J. 169, 209 (2025).

Article 
ADS 

Google Scholar
 

Law, D. D. et al. A 3D drizzle algorithm for JWST and practical application to the MIRI medium resolution spectrometer. Astron. J. 166, 45 (2023).

Article 
ADS 

Google Scholar
 

Mollière, P. et al. petitRADTRANS. A Python radiative transfer package for exoplanet characterization and retrieval. Astron. Astrophys. 627, A67 (2019).

Article 

Google Scholar
 

Brown-Sevilla, S. B. et al. Revisiting the atmosphere of the exoplanet 51 Eridani b with VLT/SPHERE. Astron. Astrophys. 673, A98 (2023).

Article 

Google Scholar
 

Zahnle, K. J. & Marley, M. S. Methane, carbon monoxide, and ammonia in brown dwarfs and self-luminous giant planets. Astrophys. J. 797, 41 (2014).

Article 
ADS 

Google Scholar
 

Lodders, K. & Fegley, B. Atmospheric chemistry in giant planets, brown dwarfs, and low-mass dwarf stars. I. Carbon, nitrogen, and oxygen. Icarus 155, 393–424 (2002).

Article 
ADS 

Google Scholar
 

Calamari, E. et al. Predicting cloud conditions in substellar mass objects using ultracool dwarf companions. Astrophys. J. 963, 67 (2024).

Article 
ADS 

Google Scholar
 

Baburaj, A. et al. A high-resolution spectroscopic survey of directly imaged companion hosts. I. Determination of diagnostic stellar abundances for planet formation and composition. Astron. J. 169, 55 (2025).

Article 
ADS 

Google Scholar
 

Balmer, W. O. et al. VLTI/GRAVITY observations of AF Lep b: preference for circular orbits, cloudy atmospheres, and a moderately enhanced metallicity. Astron. J. 169, 30 (2025).

Article 
ADS 

Google Scholar
 

Hoch, K. K. W. et al. Assessing the C/O ratio formation diagnostic: a potential trend with companion mass. Astron. J. 166, 85 (2023).

Article 
ADS 

Google Scholar
 

Kama, M. et al. Abundant refractory sulfur in protoplanetary disks. Astrophys. J. 885, 114 (2019).

Article 
ADS 

Google Scholar
 

Schneider, A. D. & Bitsch, B. How drifting and evaporating pebbles shape giant planets. II. Volatiles and refractories in atmospheres. Astron. Astrophys. 654, A72 (2021).

Article 
ADS 

Google Scholar
 

Turrini, D. et al. Tracing the formation history of giant planets in protoplanetary disks with carbon, oxygen, nitrogen, and sulfur. Astrophys. J. 909, 40 (2021).

Article 
ADS 

Google Scholar
 

Chachan, Y., Knutson, H. A., Lothringer, J. & Blake, G. A. Breaking degeneracies in formation histories by measuring refractory content in gas giants. Astrophys. J. 943, 112 (2023).

Article 
ADS 

Google Scholar
 

Tsai, S.-M. et al. Photochemically produced SO2 in the atmosphere of WASP-39b. Nature 617, 483–487 (2023).

Article 
ADS 

Google Scholar
 

Polman, J., Waters, L. B. F. M., Min, M., Miguel, Y. & Khorshid, N. H2S and SO2 detectability in hot Jupiters. Sulphur species as indicators of metallicity and C/O ratio. Astron. Astrophys. 670, A161 (2023).

Article 
ADS 

Google Scholar
 

Fu, G. et al. Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet. Nature 632, 752–756 (2024).

Article 
ADS 

Google Scholar
 

Inglis, J. et al. Quartz clouds in the dayside atmosphere of the quintessential hot Jupiter HD 189733 b. Astrophys. J. Lett. 973, L41 (2024).

Article 
ADS 

Google Scholar
 

Thorngren, D. P., Fortney, J. J., Murray-Clay, R. A. & Lopez, E. D. The mass-metallicity relation for giant planets. Astrophys. J. 831, 64 (2016).

Article 
ADS 

Google Scholar
 

Lee, E. J., Fuentes, J. R. & Hopkins, P. F. Establishing dust rings and forming planets within them. Astrophys. J. 937, 95 (2022).

Article 
ADS 

Google Scholar
 

Van Clepper, E., Price, E. M. & Ciesla, F. J. Three-dimensional transport of solids in a protoplanetary disk containing a growing giant planet. Astrophys. J. 980, 201 (2025).

Article 
ADS 

Google Scholar
 

Helled, R. & Bodenheimer, P. Metallicity of the massive protoplanets around HR 8799 If formed by gravitational instability. Icarus 207, 503–508 (2010).

Article 
ADS 

Google Scholar
 

Boley, A. C., Helled, R. & Payne, M. J. The heavy-element composition of disk instability planets can range from sub- to super-nebular. Astrophys. J. 735, 30 (2011).

Article 
ADS 

Google Scholar
 

Tobin, J. J. et al. The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) survey of Orion protostars. II. A statistical characterization of class 0 and class I protostellar disks. Astrophys. J. 890, 130 (2020).

Article 
ADS 

Google Scholar
 

Lin, J. W., Lee, E. J. & Chiang, E. A balanced budget view on forming giant planets by pebble accretion. Mon. Not. R. Astron. Soc. 480, 4338–4354 (2018).

Article 
ADS 

Google Scholar
 

Chachan, Y. et al. Kepler-167e as a probe of the formation histories of cold giants with inner super-Earths. Astrophys. J. 926, 62 (2022).

Article 
ADS 

Google Scholar
 

Mamajek, E. E. Initial conditions of planet formation: lifetimes of primordial disks. AIP Conf. Proc. 1158, 3–10 (2009).

Article 
ADS 

Google Scholar
 

Howard, S. et al. Exploring the hypothesis of an inverted Z gradient inside Jupiter. Astron. Astrophys. 680, L2 (2023).

Article 
ADS 

Google Scholar
 

Owen, T. et al. A low-temperature origin for the planetesimals that formed Jupiter. Nature 402, 269–270 (1999).

Article 
ADS 

Google Scholar
 

Chiang, E. I. & Goldreich, P. Spectral energy distributions of T Tauri stars with passive circumstellar disks. Astrophys. J. 490, 368–376 (1997).

Article 
ADS 

Google Scholar
 

Johansen, A. & Lambrechts, M. Forming planets via pebble accretion. Annu. Rev. Earth Planet. Sci. 45, 359–387 (2017).

Article 
ADS 

Google Scholar
 

McClure, M. K. et al. An Ice Age JWST inventory of dense molecular cloud ices. Nat. Astron. 7, 431–443 (2023).

Article 
ADS 

Google Scholar
 

Eistrup, C., Walsh, C. & van Dishoeck, E. F. Molecular abundances and C/O ratios in chemically evolving planet-forming disk midplanes. Astron. Astrophys. 613, A14 (2018).

Article 

Google Scholar
 

Bosman, A. D., Walsh, C. & van Dishoeck, E. F. CO destruction in protoplanetary disk midplanes: inside versus outside the CO snow surface. Astron. Astrophys. 618, A182 (2018).

Article 

Google Scholar
 

Lunine, J. I. & Stevenson, D. J. Thermodynamics of clathrate hydrate at low and high pressures with application to the outer Solar System. Astrophys. J. Suppl. Ser. 58, 493 (1985).

Article 
ADS 

Google Scholar
 

Bar-Nun, A., Kleinfeld, I. & Kochavi, E. Trapping of gas mixtures by amorphous water ice. Phys. Rev. B 38, 7749–7754 (1988).

Article 
ADS 

Google Scholar
 

Bushouse, H. et al. JWST calibration pipeline. Zenodo https://doi.org/10.5281/zenodo.7692609 (2023).

Greenfield, P. & Miller, T. The Calibration Reference Data System. Astron. Comput. 16, 41–53 (2016).

Article 
ADS 

Google Scholar
 

Agrawal, S., Ruffio, J.-B., Perrin, M., Madurowicz, A. & Sappey, B. jruffio/breads: Accepted hd19467b paper. Zenodo https://doi.org/10.5281/zenodo.11391503 (2024).

Perrin, M. D., Soummer, R., Elliott, E. M., Lallo, M. D. & Sivaramakrishnan, A. Simulating point spread functions for the James Webb Space Telescope with WebbPSF. In Proc. SPIE Conference Series, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, Vol. 8442 (eds Clampin, M. C. et al.) 84423D (SPIE, 2012).

Perrin, M. D. et al. Updated point spread function simulations for JWST with WebbPSF. In Proc. SPIE Conference Series, Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave, Vol. 9143 (eds Oschmann, J. et al.) 91433X (SPIE, 2014).

Allard, F. et al. Model atmospheres and spectra: the role of dust. In Proc. Symposium of the International Astronomical Union, Brown Dwarfs, Vol. 211 (ed. Martín, E.) 325–332 (Cambridge Univ. Press, 2003).

Ruffio, J.-B. et al. Radial velocity measurements of HR 8799 b and c with medium resolution spectroscopy. Astron. J. 158, 200 (2019).

Article 
ADS 

Google Scholar
 

Wang, J. J., Kulikauskas, M. & Blunt, S. whereistheplanet: predicting positions of directly imaged companions. Astrophysics Source Code Library ascl:2101.003 (2021).

Mollière, P. et al. Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e. Astron. Astrophys. 640, A131 (2020).

Article 

Google Scholar
 

Xuan, J. W. et al. A clear view of a cloudy brown dwarf companion from high-resolution spectroscopy. Astrophys. J. 937, 54 (2022).

Article 
ADS 

Google Scholar
 

Zurlo, A. et al. First light of the VLT planet finder SPHERE. III. New spectrophotometry and astrometry of the HR 8799 exoplanetary system. Astron. Astrophys. 587, A57 (2016).

Article 

Google Scholar
 

Xuan, J. W. et al. Validation of elemental and isotopic abundances in late-M spectral types with the benchmark HIP 55507 AB system. Astrophys. J. 962, 10 (2024).

Article 
ADS 

Google Scholar
 

Piette, A. A. A. & Madhusudhan, N. Considerations for atmospheric retrieval of high-precision brown dwarf spectra. Mon. Not. R. Astron. Soc. 497, 5136–5154 (2020).

Article 
ADS 

Google Scholar
 

Zhang, Z. et al. Elemental abundances of planets and brown dwarfs imaged around stars (ELPIS). I. Potential metal enrichment of the exoplanet AF Lep b and a novel retrieval approach for cloudy self-luminous atmospheres. Astron. J. 166, 198 (2023).

Article 
ADS 

Google Scholar
 

Zhang, Z., Mollière, P., Fortney, J. J. & Marley, M. S. Elemental abundances of planets and brown dwarfs imaged around stars (ELPIS). II. The Jupiter-like inhomogeneous atmosphere of the first directly imaged planetary-mass companion 2MASS 1207 b. Astron. J. 170, 64 (2025).

Article 
ADS 

Google Scholar
 

Morley, C. V. et al. The Sonora substellar atmosphere models. III. Diamondback: atmospheric properties, spectra, and evolution for warm cloudy substellar objects. Astrophys. J. 975, 59 (2024).

Article 
ADS 

Google Scholar
 

Ackerman, A. S. & Marley, M. S. Precipitating condensation clouds in substellar atmospheres. Astrophys. J. 556, 872–884 (2001).

Article 
ADS 

Google Scholar
 

Lei, E. & Mollière, P. easyCHEM: a Python package for calculating chemical equilibrium abundances in exoplanet atmospheres. J. Open Res. Softw. 10, 7712 (2025).

Article 
ADS 

Google Scholar
 

Rothman, L. S. et al. Hitemp, the high-temperature molecular spectroscopic database. J. Quant. Spectrosc. Radiat. Transf. 111, 2139–2150 (2010).

Article 
ADS 

Google Scholar
 

Hargreaves, R. J. et al. An accurate, extensive, and practical line list of methane for the HITEMP database. Astrophys. J. Suppl. Ser. 247, 55 (2020).

Article 
ADS 

Google Scholar
 

Polyansky, O. L. et al. ExoMol molecular line lists. XXX. A complete high-accuracy line list for water. Mon. Not. R. Astron. Soc. 480, 2597–2608 (2018).

Article 
ADS 

Google Scholar
 

Coles, P. A., Yurchenko, S. N. & Tennyson, J. ExoMol molecular line lists. XXXV. A rotation-vibration line list for hot ammonia. Mon. Not. R. Astron. Soc. 490, 4481–4488 (2019).

Article 

Google Scholar
 

Barber, R. J. et al. ExoMol line lists. III. An improved hot rotation-vibration line list for HCN and HNC. Mon. Not. R. Astron. Soc. 437, 1828–1835 (2014).

Article 
ADS 

Google Scholar
 

Azzam, A. A., Tennyson, J., Yurchenko, S. N. & Naumenko, O. V. ExoMol molecular line lists. XVI. The rotation-vibration spectrum of hot H2S. Mon. Not. R. Astron. Soc. 460, 4063–4074 (2016).

Article 
ADS 

Google Scholar
 

Allard, N. F., Spiegelman, F., Leininger, T. & Molliere, P. New study of the line profiles of sodium perturbed by H2. Astron. Astrophys. 628, A120 (2019).

Article 
ADS 

Google Scholar
 

Bernath, P. F. MoLLIST: molecular line lists, intensities and spectra. J. Quant. Spectrosc. Radiat. Transf. 240, 106687 (2020).

Article 

Google Scholar
 

Asplund, M., Grevesse, N., Sauval, A. J. & Scott, P. The chemical composition of the Sun. Annu. Rev. Astron. Astrophys. 47, 481–522 (2009).

Article 
ADS 

Google Scholar
 

Visscher, C. & Moses, J. I. Quenching of carbon monoxide and methane in the atmospheres of cool brown dwarfs and hot Jupiters. Astrophys. J. 738, 72 (2011).

Article 
ADS 

Google Scholar
 

Beiler, S. A. et al. A tale of two molecules: the underprediction of CO2 and overprediction of PH3 in late T and Y dwarf atmospheric models. Astrophys. J. 973, 60 (2024).

Article 
ADS 

Google Scholar
 

Buchner, J. et al. X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue. Astron. Astrophys. 564, A125 (2014).

Article 

Google Scholar
 

Feroz, F., Hobson, M. P., Cameron, E. & Pettitt, A. N. Importance nested sampling and the multinest algorithm. Open J. Astrophys. 2, 10 (2019).

Article 
ADS 

Google Scholar
 

Barman, T. S., Konopacky, Q. M., Macintosh, B. & Marois, C. Simultaneous detection of water, methane, and carbon monoxide in the atmosphere of exoplanet HR8799b. Astrophys. J. 804, 61 (2015).

Article 
ADS 

Google Scholar
 

Ruffio, J.-B. et al. Deep exploration of the planets HR 8799 b, c, and d with moderate-resolution spectroscopy. Astron. J. 162, 290 (2021).

Article 
ADS 

Google Scholar
 

Ruffio, J.-B. et al. Improving and assessing planet sensitivity of the GPI exoplanet survey with a forward model matched filter. Astrophys. J. 842, 14 (2017).

Article 
ADS 

Google Scholar
 

Doelman, D. S. et al. L-band integral field spectroscopy of the HR 8799 planetary system. Astron. J. 163, 217 (2022).

Article 
ADS 

Google Scholar
 

Zhang, Y. et al. The 13CO-rich atmosphere of a young accreting super-Jupiter. Nature 595, 370–372 (2021).

Article 
ADS 

Google Scholar
 

Milam, S. N., Savage, C., Brewster, M. A., Ziurys, L. M. & Wyckoff, S. The 12C/13C isotope gradient derived from millimeter transitions of CN: the case for Galactic chemical evolution. Astrophys. J. 634, 1126–1132 (2005).

Article 
ADS 

Google Scholar
 

Zhang, Y. et al. The ESO SupJup Survey. III. Confirmation of 13CO in YSES 1 b and atmospheric detection of YSES 1 c with CRIRES+. Astron. J. 168, 246 (2024).

Article 
ADS 

Google Scholar
 

Wilson, T. L. Isotopes in the interstellar medium and circumstellar envelopes. Rep. Prog. Phys. 62, 143–185 (1999).

Article 
ADS 

Google Scholar
 

Faramaz, V. et al. A detailed characterization of HR 8799’s debris disk with ALMA in band 7. Astron. J. 161, 271 (2021).

Article 
ADS 

Google Scholar
 

Phillips, M. W. et al. A new set of atmosphere and evolution models for cool T-Y brown dwarfs and giant exoplanets. Astron. Astrophys. 637, A38 (2020).

Article 

Google Scholar
 

Saumon, D. & Marley, M. S. The evolution of l and T dwarfs in color-magnitude diagrams. Astrophys. J. 689, 1327–1344 (2008).

Article 
ADS 

Google Scholar
 

Smith, M. D. Estimation of a length scale to use with the quench level approximation for obtaining chemical abundances. Icarus 132, 176–184 (1998).

Article 
ADS 

Google Scholar
 

Gierasch, P. J. & Conrath, B. J. in Recent Advances in Planetary Meteorology (ed. Hunt, G. E.) 121–146 (Cambridge Univ. Press, 1985).

Mukherjee, S. et al. Probing the extent of vertical mixing in brown dwarf atmospheres with disequilibrium chemistry. Astrophys. J. 938, 107 (2022).

Article 
ADS 

Google Scholar
 

Jura, M. Lambda Boo abundance patterns: accretion from orbiting sources. Astron. J. 150, 166 (2015).

Article 
ADS 

Google Scholar
 

Kama, M., Folsom, C. P. & Pinilla, P. Fingerprints of giant planets in the photospheres of Herbig stars. Astron. Astrophys. 582, L10 (2015).

Article 
ADS 

Google Scholar
 

Kamp, I. et al. Light element non-LTE abundances of λ Bootis stars. II. Nitrogen and sulphur. Astron. Astrophys. 375, 899–908 (2001).

Article 
ADS 

Google Scholar
 

Ruffio, J.-B. NIRSpec IFU data for HR 8799 paper. Barbara A. Mikulski Archive for Space Telescopes https://doi.org/10.17909/zzg0-hq53 (2025).

Ruffio, J.-B. & Xuan, W. JWST/NIRSpec IFU spectra of HR 8799 c, d, e (2.9–5.2 um; R∼2,700). Zenodo https://doi.org/10.5281/zenodo.17536808 (2025).

Guillot, T. et al. Giant planets from the inside-out. In Proc. SPIE Conference Series, Protostars and Planets VII, Vol. 534 (eds Inutsuka, S. et al.) 2205.04100 (SPIE, 2023).

Atreya, S. K. et al. in Saturn in the 21st Century (eds Baines, K. H. et al.) 5–43 (Cambridge Univ. Press, 2018).

Comments are closed.