Observation of water in exoplanets

Observation of water in exoplanets Image credit Shutterstock Jonathan Tennyson Physics and Astronomy, University College London Oct 2025 Oleron Methods for getting spectra of exoplanets 1. Transit spectroscopy 2. Cross correlation spectroscopy (High resolution Doppler shift) 3. Direct imaging + Straightforward observation easier to interpret + See planets early in their formation cycle - Angular resolution means planet must be far from its star + nearby - Very few candidate planetary systems (and spectra) - Cannot be used for the vast majority of exoplanets Resolving power in principle arbitrary Direct imaging spectroscopy: Good for large, young planets far from their planet Transit spectrscopy Thanks to Angelos Tsiaris Beaulieu et al., 2007 Knutson et al., 2007 HD189733b: Primary transit with Spitzer Tinetti et al., Nature, 448, 163 (2007) Water, different T-P Water line list: BT2 Barber et al., 2006 Confirmation of Water,methane and hazes! Beaulieu et al., 2007 Knutson et al., 2007 Swain et al., 2008 Pont et al., 2007 G. Tinetti (private communication, 2008) JWST: James Web Space Telescope General purpose observatory ~25% time for exoplanets Infrared capability "High" resolution (R ~ 3000) First data released Transit spectroscopy Direct imaging T 4.5 Observed (SpeX@IRTF) Spectrum T4.5 brown dwarf: a “methane dwarf” Cushing ,Rayner, Vacca (2005) VSTAR STDS CH4 (empirical) 2MASS 0559-14 T 4.5 Observed (SpeX@IRTF) Spectrum T4.5 brown dwarf: a “methane dwarf” Cushing ,Rayner, Vacca (2005) VSTAR STDS CH4 (empirical) VSTAR ExoMol CH4 (10to10) SN Yurchenko, J Tennyson, J Bailey, MDJ Hollis, G Tinetti, PNAS, 111, 9379 (2014) 2MASS 0559-14 Cool atmospheres: dominated by molecular absorption Brown Dwarfs M-dwarf The molecular opacity problem Exoplanets? M Dwarf Planet Marley & Leggett (2008) Ab initio calculations DMS PES Variational calculations Rovibrational wavefunctions Rovibrational energies Intensities (Einstein Aif) Line list Refinement Method: Spectrum from the “first-principles” BT2 linelist used to to detect/model water Nova-like V838 Mon Cometary coma Atmosphere of Venus Exoplanets Brown and M-dwarfs As well as..... Water concentrations in explosions Design of high-T gas sensors Remote detection of forest fires Imaging gas turbine engines Temperature profile in flames Atmospheric models I. BeH, MgH, CaH II. SiO III. HCN/HNC IV. CH4 V. NaCl, KCl VI.PN VII. PH3 VIII. H2CO IX. AlO X. NaH XI. HNO3 XII. CS XIII. CaO XIV. SO2 XV. HOOH XVI. H2S XVII. SO3 XVIII. VO XIX. H218O, H217O XX. H3+ XXI. NO XXII. SiH4 XXIII. PO, PS XXIV. SiH XXV. SiS XXVI. SN, SH XXVII. AlH XXVIII. C2H4 XXIX. CH3Cl XXX. H216O XXXI. C2 XXXII. TiO XXXIII. MgO XXXIV. PH XXXV. NH3 XXXVI SH (UV) XXXVII HCCH XXXVIII SiO2 XXXIX CO2 XL. H3O+ XLI. NaOH, KaOH XLII. NO (UV) XLIII. SiO (UV) XLIV. NaO XLV. MgH (UV), CaH (UV) XLVI. SiN XLVII. CaOH XLVIII AlCl XLVIIII H2CS L. H3+, H2D+, D2H+, D3+ Li. LiOH LII. CH+ LIII. YO LIV. VO (hyperfine) LV. AlH (predissociation) Hot line lists; Published in MNRAS LVI. SO LVII. CH4 LVIII. OCS LIX. N2O LX. 15NH3 LXI. OH LXII. C3 LXIII. HDO LXIV. PN LXV. NiH LVI. CO2 In progress O2, CS2, HCO+,NO+, OH+, BH, etc 2024 data releases: J. Tennyson et al., JQSRT, 326, 109083 (2024) M Brogi, IAG Snellen et al, Nature, 486, 502 (2012) J L Birkby, Exoplanet Atmospheres at high spectral resolution (2018) High resolution Doppler-shift spectroscopy High resolution Doppler-shift spectroscopy J L Birkby et al, (2017) Exoplanet Atmospheres at High Spectral Resolution Snellen, IAG 2025 ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS 63 , pp.83-125 Cross correlation give detection(s) Gandhi+ MNRAS 495, 224 (2020) Water MARVEL projects H216O and line lists 1. IUPAC H217O, H218O, Tennyson+, JQSRT, 110, 573-596 (2009). HDO, Tennyson+, JQSRT, 111, 2160-2184 (2010). H216O, Tennyson+, JQSRT, 117, 29-80 (2013). 184 667 transitions 18486 energies D2O, Tennyson+, JQSRT, 142, 93-108 (2014) 2. MARVEL III (high accuracy levels) H216O, Tobias+, Phys. Chem. Chem. Phys., 21, 3473-3495 (2019). 3. W2020 H216O, Furtenbacher+, J. Phys. Chem. Ref. Data,49, 033101 (2020). 270 745 transitions, 19024 energies H217O, H218O + H216O update Furtenbacher+, J. Phys. Chem. Ref. Data,49, 043103 (2020). 4. W2024 H216O, Furtenbacher+, Sci. Data, 11, 1058 (2024) 309 290 transitions, 19027 energies BT2 Barber+ MNRAS, 368, 1087-1094 (2006). POKAZATEL Polyansky+ MNRAS, 480, 2597-2608 (2018). UCLH2O296 Zobov+ in preparation I. BeH, MgH, CaH II. SiO III. HCN/HNC IV. CH4 V. NaCl, KCl VI.PN VII. PH3 VIII. H2CO IX. AlO X. NaH XI. HNO3 XII. CS XIII. CaO XIV. SO2 XV. HOOH XVI. H2S XVII. SO3 XVIII. VO XIX. H218O, H217O XX. H3+ XXI. NO XXII. SiH4 XXIII. PO, PS XXIV. SiH XXV. SiS XXVI. SN, SH XXVII. AlH XXVIII. C2H4 XXIX. CH3Cl XXX. H216O XXXI. C2 XXXII. TiO XXXIII. MgO XXXIV. PH XXXV. NH3 XXXVI SH (UV) XXXVII HCCH XXXVIII SiO2 XXXIX CO2 XL. H3O+ XLI. NaOH, KaOH XLII. NO (UV) XLIII. SiO (UV) XLIV. NaO XLV. MgH (UV), CaH (UV) XLVI. SiN XLVII. CaOH XLVIII AlCl XLVIIII H2CS L. H3+, H2D+, D2H+, D3+ Li. LiOH LII. CH+ LIII. YO LIV. VO (hyperfine) LV. AlH (predissociation) Hot line lists; Published in MNRAS MARVELised MARVEL in progress 2024 data releases: J. Tennyson et al., JQSRT (now online) LVI. SO LVII. CH4 LVIII. OCS LIX. N2O LX. 15NH3 LXI. OH LXII. C3 LXIII. HDO LXIV. PN LXV. NiH LVI. CO2 Sample detections of water and methane HD 189733b Transit 51Eri b Direct imaging HD 102195b Cross correlation J. Tennyson & S.N.Yurchenko ExoMol@10, Astron. Geophys. 21, 6.17 (2021) Extension to the Ultraviolet: Into the deep blue yonder Line spectra Continuum absorption/ Photodissociation Predissociation J. Tennyson, M. Pezzella and Jingxin Zhang and S.N. Yurchenko, Data structures for photoabsorption within the ExoMol project, RAS Tech. Instr., 2, 231-237 (2023) Photodissociation Fragmentation of a molecule after absorption one or more photons. Direct photodissociation: Indirect photodissociation: Reinhard Schinke, Photodissociation Dynamics Spectroscopy and Fragmentation of Small Polyatomic Molecules, Cambridge University Press (1993). Photodissociation in Astrochemistry UNIMAP / L. Piazzo, La Sapienza, Roma; E. Schisano / G. Li Causi, IAPS/INAF, Italy ESA/Herschel/PACS, SPIRE/Hi-GAL Project. ~ 102-106particles/cm3 Photodissociation impacts atmospheres of exoplanets in UV-rich environments. Temperature-dependent models required; curreny state-of-the-art photodissociation calculations based on the interstellar medium (ie T=0 K). Measurements: O. Venot et al, ApJ, 2016, 830, 77; B. Fleury et al, ApJ, 2019, 871, 158; N. K. Lewis et al, ApJL, 2020, 902, L19. Leiden database: A. N. Heays et al, A&A, 2017 602, A105. + Atmospheric density from Jupiter, temperature from WASP-121b stratosphere. Duo: S. N. Yurchenko et al ,CPC, 2016,202, 262–275; https://github.com/Trovemaster/Duo Given the potential energy curves and transition dipole moments between them, program Duo solves the 1-D Schrödinger equation and calculates intensities. 𝜎𝑓𝑖 𝜈 = 𝐼 𝑓 ← 𝑖 𝑓 𝜈𝑓𝑖 𝜈 σrecovered with ExoCross, applying a line profile to the intensity: ExoCross S. N. Yurchenko et al, A&A,2018,614, A131; https://github.com/Trovemaster/exocross/ Our Approach Marco Pezzella Post processing of the data •Discretized continuum spectrum •Gaussian smoothing function •Full rovibrational treatment to allow for T-dependence Our Approach M. Pezzella, S.N. Yurchenko and J. Tennyson, A method for calculating temperaturedependent photodissociaiton cross sections and rates, Phys. Chem. Chem. Phys.,23, 16390-16400 (2021). 0 2×1010 4×1010 6×1010 0.0 5.0×106 1.0×107 1.5×107 I [photons s-1 cm-2 nm-1] 0200 400 600 800 1000 1200 1400 1600 1800 λ [nm] 0.0 5.0×105 1.0×106 1.5×106 2.0×106 4000 K 10,000 K 20,000 K B-type star: very luminous and blue stars. They are energetic and short lived. Fields Black Body flux T Tauri stars: young stars moving towards the main sequence. Herbig Ae stars: young A stars. They are still embedded in gas dust envelope. nm Computed rate of photodissociation of HCl in different radiation fields •Temperature of the molecule M. Pezzella, J. Tennyson S.N. Yurchenko, MNRAS 514, 4413-4425 (2022) Computed photodissociation cross sections: T-dependent G.B. Mitev, M Pezzella, Jingxin Zhang, S.N. Yurchenko and J. Tennyson, ExoMol Photodissociation Cross Sections – II: Continuum Absorption and Predissociation Spectra for the Hydroxyl Radical, Mon. Not. R. astr. Soc., 539, 3732-3740 (2025). Leiden database Temperature-dependence of HCN photodissociation M. Pezzella, S.N. Yurchenko, J. Tennyson and A. Mitrushchenkov, Phys. Chem. Chem. Phys., 26, 27519-27529 (2024). H2O Leiden A. N. Heays et al. “Photodissociation and photoionisation of atoms and molecules of astrophysical interest” A&A 602 A105 (2017) Assumes T = 0 K Photodissociation of water as a function of T H2O – A Coupled Three-State Model asym. stretch θ = 104.5°, r1 = 1.0 Å Armendo Perri H2O – A Coupled Three-State Model Renner-Teller and non-adiabatic effects near linear geometries asym. stretch θ = 180.0°, r1 = 1.0 Å Functional form preserves both spin and spatial conservation rules H2O Experiment Q.-H. Ni et al. “ExoPhoto: A database of temperature-dependent photodissociation cross sections” RASTI (2025) A. Fateev et al. DTU (unpublished) H2O – Direct Photodissociation Q.-H. Ni et al. “ExoPhoto: A database of temperature-dependent photodissociation cross sections” RASTI (2025) A. Fateev et al. DTU (unpublished) H2O – Direct Photodissociation Note: We need an improved fit along symmetric stretch coordinate for B state PES + better XB dipoles To be continued..... database with new features www.exomol.com 1. Molecular line lists 2. Cross-sections 3. Partition functions 4. Broadening parameters 5. k-tables and opacities (Chubb+ MNRAS 2021) 6. Lifetimes (Tennyson+ J Phys B, 49, 044002 (2016)) 7. Cooling functions 8. Lande g-factors (Semenov+, J Mol Spectrosc 2016) 9. Dipoles for molecular control/orientation effects A Yachmenev, RichMol project (Owens+ Sci Rep 2017) 10. Specific heats (NASA polynomials) (Wang+ JQSRT 2023) 11. LiDB Lifetimes database (Owens+ PSST 2023, JQSRT 2025) 12. ExoMolHR: high res spectra (Zhang+ ApJS 2025) 13. ExoPhoto Photodissociation (Ni+ RASTI 2025) 14. ExoAtom atomic line list (Ni+ RASTI submitted) 14. Application program interface (API) + data products J. Tennyson, S.N. Yurchenko, J. Zhang and others, The 2024 release of the ExoMol database: molecular line lists for exoplanet and other hot atmospheres, J. Quant. Spectrosc. Rad. Transf., 326, 109083 (2024) Coming soon: Cooling functions With huge thanks to Sergey Yurchenko Oleg Polyansky ExoMol (2011-16) Ahmed Al-Refaie (UCL) Ala’a Azzam (Univ Jordan) Emma Barton Bob Barber Katy Chubb (Bristol) Philip Coles Maire Gordan (Sussex) Christian Hill (IAEA) Lorenzo Lodi Laura McKemmish (UNSW) Alec Owens Andrei Patrascu (ELI-NP, Romania) Clara Sousa-Silva (Bard College) Tom Rivlin (Graz) Dan Underwood Andrey Yachmenev (DESY) Emil Zak ExoMolHD (2020-25) HiRes Line lists Charles Bowesman Kyriaki Kefala Qianwei Qu Mikhail Semenov Apoorva Uphadyay Alex Smola Tony Tao Photodissociation Marco Pezzella Georgi Mitev Armando Perri Pressure broadening Elizabeth Guest Andrei Solokov Ryan Brady Jeanna Buldyreva (Bourgogne) Bob Gamache (UMass) Database Jingxin Zhang Qing-He Ni Terrance Corey Christian Hill (IAEA)