Small planet atmospheres from the ground: state-of-the-art and future perspectives

ENRIC PALLE Small planet atmospheres from the ground: state-of-the-art and future perspectives Time As of today 259 planets explored, 61 species detected Only 121 planets with detected atmospheres The big majority are giant planets Detecting Exoplanet Atmospheres is Challenging One of the main objectives of 21st century astronomy is detecting the atmospheres of small rocky planets in the HZ, and searching for potential biomarkers BIOMARKERS: A combination of atmospheric species in chemical disequilibrium that are indicative of life Detecting Small Exoplanet Atmospheres is Very Challenging 2 to 3 orders of magnitude in sensitivity Search for biomarkers = Studying the atmosphere Palle, et al, Nature (2009) Earth’s transmission spectrum The 39-M ELT -2028 Technical first light & Science verification The ELTs Top Science: Rocky planet atmospheres and biomarker search GMT TMT E-ELT European ELT Instruments for exoplanets OBSERVING MODES: THE FIBRE FEEDING ‣Modular instrument ‣Different observing modes from different fiber bundles ‣No moving parts in spectrographs: stability! Time line: Currently on Phase B (PDR). On Sky 2031 A SUBSET OF ANDES SCIENCE CASES Exoplanets (characterisation of Exoplanets Atmospheres: detection of signatures of life) Protoplanetary Disks (dynamics, chemistry and physical conditions of the inner regions) Stellar Astrophysics (abundances of solar type and cooler dwarfs in galactic disk bulge, halo and nearby dwarfs: tracing chemical enrichment of Pop III stars in nearby universe) Stellar Populations (metal enrichment and dynamics of extragalactic star clusters and resolved stellar populations) Intergalactic Medium (Signatures of reionization and early enrichment of ISM & IGM observed in high-z quasar spectra) Galaxy Evolution (massive early type galaxies during epochs of formation and assembly) Supermassive Black Holes (the low mass end) Fundamental Physics (variation of fundamental constants - 𝛼, mp/me Sandage Test) Community White Paper: Maiolino et al. 2013, ArXiV:1310.3163 SCIENCE PRIORITIES Priority 1: Exoplanet atmospheres via transmission spectroscopy (potential detection of bio-signatures) TLR 1: R > 100,000, 0.5-1.8 μm, et alia; drive the ANDES baseline design Enables: reionization of Universe; characterization of Cool stars Doable: detection and investigation of near pristine gas; 3D reconstruction of the CGM; Extragalactic transients Priority 2: Variation of the fundamental constants of Physics TLR 2: blue extension to 0.37 μm Enables: Cosmic variation of the CMB temperature, Determination of the deuterium abundance; investigation and characterization of primitive stars Priority 3: Exoplanet atmospheres via reflection spectroscopy (potential detection of bio-signatures) TLR 3: SCAO+IFU Enables: Planet formation in protoplanetary disks; characterization of stellar atmospheres; Search of low mass Black Holes Doable: characterization of the physics of protoplanetary disks Priority 4: Redshift drift (Sandage test) TLR 4: 𝜆 accuracy 2 cm/s, stability 2 cm/s Enables: Mass determination of exoplanets (Earth-like objects) Doable: Radial velocity search for exoplanets around M-dwarf stars SMALL (<4 RE) EXOPLANET ATMOSPHERES Red line marks the 5 sigma detection in 1 transits The known population of small planets Palle et al 2024 EARTH-LIKE (<1.5 RE) EXOPLANET ATMOSPHERES LHS 457b Lustig-yaeger et al, 2023 GJ486b Moran et al 2023 JWST : Starting to explore small worlds atmospheres However, small (earth-size) planets remain an open question EARTH-LIKE EXOPLANET ATMOSPHERES Exoplanet Atmospheres: transmission spectroscopy M dwarf Trappist 1 planets: •1.3-1.7 um H2O band at an SNR of 6 in 2 transits •0.9-1.1 um H2O band in 4 transits •CO2in 4 transits. •O2detected in 25 transits. For these planets, the transit duration is <1 hour EARTH-LIKE EXOPLANET ATMOSPHERES Broken lines mark the 5 sigma detection in 5 transits for CO2-dominated and earth-like atmospheric compositions The known population of small planets 100-night (4 months with overheads) program explores the best 40 HZ transiting planets in TS at the 5 sigma level. Palle et al 2024 EARTH-LIKE EXOPLANET ATMOSPHERES Exoplanet Atmospheres : transmission vs direct light Probability of transits of Earth - Sun 0.5% Probability of transit of Earth –M star 1-2% •We will only be able to explore in transmission 1/200 of the closest Sun-Earth twins •We will only be able to explore in transmission 1/50 of the closest Earth-like planets around M stars •Probabilities and distances= photons Transmission spectroscopy probes the (upper) atmosphere of the planet Reflected light from telluric planets probes down to the surface, including surface features (biomarkers) EARTH-LIKE EXOPLANET ATMOSPHERES Direct detection of the planet’s reflected light ANDES Golden Sample: Palle et al 2024 EARTH-LIKE EXOPLANET ATMOSPHERES Direct detection of the planet’s reflected light Palle et al 2024 EARTH-LIKE EXOPLANET ATMOSPHERES For very nearby planets, the combination of ANDES, HARMONI and METIS will provide a very detailed characterization Transparency by Jayne Birkby “ADDITIONAL” EXOPLANET SCIENCE Disk Science Compositional and kinematical properties The scenarios of planet formation (Gaps in disks, Planet impact formation) Earth-analogs Radial velocity mass measurements Earth-like masses around solar analogs measured within 10% Targeted RV searches (for key planetary systems) Giant planets chemistry and dynamics at unprecedented detail Possible Extension to K band “CO machine” for gas giant planets: tracer of atmospheric dynamics. Doppler tomography maps of directly-imaged exoplanets Possible Extension to U band Atmospheres of young habitable planets (Ozone absorption, Rayleigh slopes Hot exoplanets: Calcium “atmospheres” (Mercury-like sputtering for hot rocky planets)