The GAPS Programme at TNG XXXVIII. Five molecules in the atmosphere of the warm giant planet WASP-69b detected at high spectral resolution

Abstract

Context.Aims. The field of exo-atmospheric characterisation is progressing at an extraordinary pace. Atmospheric observations are now available for tens of exoplanets, mainly hot and warm inflated gas giants, and new molecular species continue to be detected revealing a richer atmospheric composition than previously expected. Thanks to its warm equilibrium temperature (963±18 K) and low-density (0.219±0.031 g cm −3 ), the close-in gas giant WASP-69b represents a golden target for atmospheric characterisation. Methods. With the aim of searching for molecules in the atmosphere of WASP-69b and investigating its properties, we performed high-resolution transmission spectroscopy with the GIANO-B near-infrared spectrograph at the Telescopio Nazionale Galileo. Results. We observed three transit events of WASP-69b. During a transit, the planetary lines are Doppler-shifted due to the large change in the planet's radial velocity, allowing us to separate the planetary signal from the quasi-stationary telluric and stellar spectrum. Conclusions. Considering the three nights together, we report the detection of CH4, NH3, CO, C2H2, and H2O, at more than 3.3σ level. We did not identify the presence of HCN and CO2 with confidence level higher than 3σ. This is the first time that five molecules are simultaneously detected in the atmosphere of a warm giant planet. These results suggest that the atmosphere of WASP-69b is possibly carbon-rich and characterised by the presence of disequilibrium chemistry.

Chemical Diversity in Protoplanetary Disks and Its Impact on the Formation History of Giant Planets

“…These results expand those of Paper I, showing how the relative values of the normalized ratios follow the same patterns independently on the underlying chemical scenario. These behaviors have been recently confirmed in the studies of Biazzo et al (2022), Carleo et al (2022), andGuilluy et al (2022), based on Paper I.…”

“…For instance, observations by Giacobbe et al (2021) of the hot Jupiter HD 209458b, at the equilibrium temperature of 1500 K, revealed the presence of H 2 O, CO, HCN, CH 4 , NH 3 , and C 2 H 2 in the atmosphere. Carleo et al (2022) and Guilluy et al (2022) have recently extended this result to giant planets with equilibrium temperature T 1000 K. Future observations with JWST (Greene et al 2016), Twinkle (Edwards et al 2019b), and Ariel (Tinetti et al 2018), as well as advances in atmospheric retrieval techniques, will soon revolutionize the field. The broad spectral range and the high spectral resolution of JWST will allow for precise determination of the abundances of a number of species of interest besides H 2 O, like CO, CO 2 , CH 4 , and NH 3 (Greene et al 2016).…”

“…If, instead, the planet formed around a star characterized by a subsolar C/O ratio (e.g., 0.45), the planetary C/O ratio should be correctly interpreted as superstellar. Our methodology has been recently successfully applied by Carleo et al (2022) and Guilluy et al (2022) to the interpretation of observational data from the GAPS 2 program.…”

“…Recent studies have validated our methodology on real data in preparation of its use for interpreting the observations of future ground-based and space-based facilities. Alongside Carleo et al (2022) and Guilluy et al (2022), Biazzo et al (2022) put constraints on possible formation scenarios for the giant planets in four planetary systems, around the stars HAT-P-26, WASP-39, HAT-P-12, and WASP-10. Specifically, they analyzed the trends of the normalized planetary metallicity and elemental ratios based on the atmospheric composition obtained by Kawashima & Min (2021) through spectral disequilibrium retrieval models.…”

The GAPS Programme at TNG XXXIX. Multiple Molecular Species in the Atmosphere of the Warm Giant Planet WASP-80 b Unveiled at High Resolution with GIANO-B ∗

“…While Fossati et al 2022 presented an analysis of the optical portion of these observations together with a search for He I, in this work we mainly exploit the nIR GIANO-B data, in order to search for molecules in the atmosphere of this planet. These observations are part of the GAPS2 22 programme, aimed at exploring the diversity of planetary systems via the detection of planets around young stars (e.g., Carleo et al 2020;Damasso et al 2020), the search for inner small planetary companions to outer long-period giants (e.g., Barbato et al 2020), and the observation and characterization of planetary atmospheres (e.g., Borsa et al 2019;Guilluy et al 2020;Pino et al 2020;Giacobbe et al 2021;Guilluy et al 2022). GIANO-B covers a wavelength range of 0.95-2.45 μm split in fifty orders with a resolving power of R ∼ 50,000.…”