ARIEL Open Conference – ESTEC 2020 Exoplanet missions – next decade ARIEL Open Conference – ESTEC 2020 What are exoplanet made of? • How do planets and planetary systems form? • How do planets and their atmospheres evolve over time? ARIEL Open Conference – ESTEC 2020 ARIEL • Selected as ESA M4 mission in March 2018 (launch 2028) • 1-m telescope, spectroscopy from VIS to IR • ~1000 exoplanets observed (rocky + gaseous) • Simultaneous coverage 0.5-7.8 micron • Payload consortium: 17 ESA countries + US CASE & JP understudy ARIEL Open Conference – ESTEC 2020 ARIEL • Launch direct to L2 by Ariane 6-2 • Shared launch with F-mission • 4 year baseline mission (extendable to 6 years) ARIEL Open Conference – ESTEC 2020 ARIEL – payload design summary PHASE B1: JUST PASSED PAYLOAD DESIGN CONSOLIDATION REVIEW ARIEL Open Conference – ESTEC 2020 ARIEL – Spectral range/resolution The Astronomical Journal, 157:242 (17pp), 2019 June Edwards et al. SIM ULTANEO US COVERAGE 0.5-7.8 MICRON Table 1 2. Creation of a Catalog of Exoplanets Wavelength Ranges and Spectral Resolutions of Ariel’s Instrumentation 2.1. Known Exoplanets Instrument Name Wavelength Range (μm) Resolution Exoplanetary data was downloaded from NASA’s Exoplanet VISPhot 0.5–0.6 Archive in order to account for all confirmed planets before FGS 1 0.6–0.81 Photometric bands being filtered such that only transiting planets were considered. FGS 2 0.81–1.1 The database was last accessed on 2019 February 26. However, NIRSpec 1.1–1.95 20 the major exoplanet catalogs are sometimes incomplete and thus an effort has been made here to combine them (for AIRS Ch0 1.95–3.9 100 a review of the current state of exoplanet catalogs, see AIRS Ch1 3.9–7.8 30 Christiansen 2018). Hence, the data was verified, and in some cases gaps filled, utilizing the Open Exoplanet Catalog (Rein 2012), exoplanet. eu (Schneider et al. 2011), and TEPCat (Southworth 2011). the most favorable targets. It willARIEL also Open Conference enable – ESTEC the 2020 study of Planets not included in the NASA Exoplanet Archive were not thermal and scattering properties of the atmosphere as the added to the analysis to ensure that only confirmed planets planet orbits around the star. A basic summary of Ariel’s were utilized. As of 2019 March, 3022 planets within the instrumentation is given in Table 1. For more detail on the NASA Exoplanet Archive were sufficiently characterized for Ariel design see Tinetti et al. (2018). inclusion in this analysis. Ariel will enable the simultaneous study of exoplanets at Unknown parameters were inferred based on the following multiple wavelengths through transit, eclipse, and phase-curve assumptions. observations (see, e.g., Tinetti et al. 2013 for an overview of the 1. If the inclination is known, the impact parameter is information content of these techniques). During transit, stellar calculated from light can be observed passing through the terminator region of aicos() the planet (transmission spectroscopy). Similarly, when the star b = .1() eclipses the planet (i.e., the planet passes behind its host star in R* our line of sight) the flux difference resulting from the planet’s 2. Else, it was assumed that b=0.5 (i.e., the midpoint of day-side emission or reflection (emission or reflection the equator and limb of the star). spectroscopy) can be measured. Phase curves are observed by 3. The planetary effective temperature (Tp) is estimated monitoring the star–planet system over a large portion of the from planets orbit. Here, we focus on transit and eclipse observations ⎛ ⎞12 as these will be the main science observations. Additional 1 - AR* TTp = *⎜ ⎟ ,2() science time to be dedicated to phase curves is currently under ⎝ 2a ⎠ study. where a greenhouse effect of ò=0.8 and a planetary During Phase A, a study of Ariel’s capabilities to observe albedo of A=0.3 (TP<700 K) or A=0.1 (Tp>700 K) known and predicted planets was conducted and a mission are assumed (Seager & Mallén-Ornelas 2003; Tessenyi reference sample (MRS; i.e., a list of exoplanets to be observed et al. 2012). during the primary mission life) of ∼1000 potential targets was 4. Planetary mass (Mp) was estimated utilizing Forecaster created (Zingales et al. 2018). Here an updated review of the (Chen & Kipping 2017). performance of Ariel’s instrumentation to observe currently 5. Atmospheric molecular mass was assumed to be 2.3. known planets and potential future detections by TESS is undertaken. According to a recent study by Barclay et al. 2.2. Future Planet Discoveries (2018), TESS is anticipated to detect over 4500 planets around bright stars and nearly 10,000 giant planets around fainter stars. TESS and other surveys are predicted to discover thousands The predicted TESS discoveries are incorporated into our of planets around bright stars. In the first two years of analysis to test Ariel’s capabilities. The list of known and operation, TESS is anticipated to detect over 4500 planets predicted exoplanets are analyzed using the Ariel radiometric around bright stars and more than 10,000 giant planets around model (ArielRad; L. Mugnai et al. 2019, in preparation), a new fainter stars (Barclay et al. 2018). Here, these predicted TESS Ariel simulator which is more suitable to capture the details and discoveries around brighter stars are incorporated into the analysis to highlight Ariel’s capabilities to study anticipated updates of Ariel’s design as considered in Phase B (see 4 Section 3.2). ArielRad includes greater margins on the future discoveries. The MAST archive has been utilized to fl obtain stellar parameters for these planets by cross-referencing instrument noise and an additional noise oor of 20 ppm than fi the previously used ESA radiometric model (Puig et al. 2015). the Gaia catalog. The rst planets from TESS have begun to be discovered (e.g., Huang et al. 2018) but these have not been This exercise will be regularly repeated to incorporate new included in this work to avoid overlap with the predicted yield. discoveries and validate that the mission’s science goals can be The known and predicted exoplanets were compiled into a achieved as the instrumentation evolves in Phase B. single data set (∼7000 planets), which has been used to analyze Finally we focus part of our simulations and discussion on ’ fi Ariel s capabilities and provide an indicative look at the smaller planets to re ne some of the science objectives number and type of planets Ariel could observe. considered in Phase A for the mission and address new science questions emerging from the recent discoveries, e.g., the Fulton gap (Fulton & Petigura 2018). 4 https://archive.stsci.edu 2 ARIEL – payload contributions ARIEL Open Conference – ESTEC 2020 ARIEL – Sky visibility Instantaneous Sky 100% 80% 60% 40% Survey Visibility ARIEL Open Conference – ESTEC 2020 Deep Benchmark ARIEL team growing ARIEL Open Conference – ESTEC 2020 ARIEL Science WG in Phase B ARIEL Open Conference – ESTEC 2020 ARIEL 4-Tier approach • Main atmospheric component INDIVIDUAL PLANETS & POPULATION ANALYSIS • Trace gases SURVEY • Thermal structure • What fraction of planets have clouds? • Cloud characteriza@on • Have small planets still retained H/He? DEEP SURVEY • Elemental composi@on • Colour-colour diagrams • Refinement of orbital/planet BENCHMARK parameters in IR ~ 50-100 • Atmospheric circulation ~ 500 • Spatial & temporal • Phase-curves variability ~ 1000 PLANETS • Tailored observations ARIEL Open Conference – ESTEC 2020 ARIEL Data: Tier 2 spectra Optimal SNR/R to retrieve: • Main/trace gases abundances • Thermal & chemical profiles • Cloud characterisation HD209458b: 1 transit GJ1214b: 5 transits ARIEL Open Conference – ESTEC 2020 Venot et al. (2013, 2018a). As it can be seen on Fig. 15, there is a strong temperature dependency of σCO2 (λ,T) and the variation of the absorption depends on wavelength. Around Lyman ↵, there are about two orders of magnitude between the two extreme temperatures, but the variation is less important in the [130–150] nm range. For wavelengths longer than 160 nm, the increase of the absorption cross section together with the temperature is more marked. About 200 nm, there are four orders of magnitude between σ (150 K) and σ (800 K). ⇠ CO2 CO2 These high-temperature data have been included in the 1D photochemical model of Venot et al. (2012) in order to evaluate the impact of these new data on the atmospheric composition predicted by this kinetic model. It appears that in an atmosphere at 800 K 10-4 800 K 10-3 10-2 OH -1 H 10 CH4 100 Pressure (mbar) 1 10 CO2 CH3 2 Atmospheric10 chemistryH2O 103 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 SIMULATIONS10 10 10& RETRIEVAL10 10 OF10 CHEMICAL10 10 10PROFILES10 10FROM10 ARIEL10 10 TIER-2 SPECTRA Molar fraction 10-4 800 K 10-3 HCN NO 10-2 10-1 100 N O Pressure (mbar) 2 101 2 10 NH3 NH2 103 10-15 10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 Molar fraction Venot et al., 2018 Changeat et al, 2019 Figure 16: Abundances vertical profiles of selected species impacted by the change of CO2 absorption cross section. The abundances calculated with σCOARIEL2 (300 Open K) Conference are represented – ESTEC 2020 with full lines whereas that calculated with σCO2 (800 K) are represented with dashed lines. Adapted from Venot et al. (2018a). at P< 10 mbar (i.e. where most of photodissociations occur) using the absorption cross section of CO2 corresponding to this temperature instead of that at room temperature has an impact on the photodissociation rate of CO2 and thus the chemical composition of the atmosphere is modified (see Fig.