Context. High CO depletion as well as depletion of N-bearing species is observed in dense pre-stellar cores. It is generally accepted that depleted species freeze out onto dust grains to form icy mantles and that these ices suffer energetic processing due to cosmic ion irradiation and ion-induced UV photons. Aims. The aim of this work is to study the chemical and structural effects induced by ion irradiation on different CO:N 2 mixtures at low temperature (16 K) to simulate the effects of cosmic ion irradiation of icy mantles. Methods. Different CO:N 2 mixtures and pure CO and pure N 2 were irradiated with 200 keV H + at 16 K. Infrared transmittance spectra of the samples were obtained in situ before and after irradiation. The samples were warmed up and spectra were taken at different temperatures. The residues left over on the substrate at room temperature were analysed ex situ by micro Raman spectroscopy. Results. Several new absorption features are present in the infrared spectra after irradiation, indicating that new species are formed. The most abundant are nitrogen oxides (such as NO, NO 2 and N 2 O), carbon chain oxides (such as C 2 O, C 3 O and C 3 O 2 ), carbon chains (such as C 3 and C 6 ), O 3 and N 3 . A refractory residue is also formed after ion irradiation and is clearly detected by Raman spectroscopy. Conclusions. We suggest that carbon chains and nitrogen oxides observed in the gas phase towards star-forming regions are formed in the solid phase after cosmic ion irradiation of icy grain mantles and are released into the gas phase after desorption of grain mantles. We expect that the Atacama Large Millimeter/submillimeter Array (ALMA), thanks to its high sensitivity and resolution, will increase the number of nitrogen oxides and carbon chain oxides detected towards star-forming regions.

Context. Giant planets in short-period orbits around bright stars represent optimal candidates for atmospheric and dynamical studies of exoplanetary systems. Aims. We aim to analyse four transits of WASP-33b observed with the optical high-resolution HARPS-N spectrograph to confirm its nodal precession, study its atmosphere, and investigate the presence of star-planet interactions. Methods. We extracted the mean line profiles of the spectra using the least-squares deconvolution method, and we analysed the Doppler shadow and the radial velocities. We also derived the transmission spectrum of the planet, correcting it for the stellar contamination due to rotation, centre-to-limb variations, and pulsations. Results. We confirm the previously discovered nodal precession of WASP-33b, almost doubling the time coverage of the inclination and projected spin-orbit angle variation. We find that the projected obliquity reached a minimum in 2011, and we used this constraint to derive the geometry of the system, and in particular its obliquity at that epoch (ϵ = 113.99° ± 0.22°) and the inclination of the stellar spin axis (is = 90.11° ± 0.12°). We also derived the gravitational quadrupole moment of the star J2 = (6.73 ± 0.22) × 10−5, which we find to be in close agreement with the theoretically predicted value. Small systematics errors are computed by shifting the date of the minimum projected obliquity. We present detections of Hα and Hβ absorption in the atmosphere of the planet, with a contrast almost twice as small as that previously detected in the literature. We also find evidence for the presence of a pre-transit signal, which repeats in all four analysed transits and should thus be related to the planet. The most likely explanation lies in a possible excitation of a stellar pulsation mode by the presence of the planetary companion. Conclusions. A future common analysis of all available datasets in the literature will help shed light on the possibility that the observed Balmer lines’ transit depth variations are related to stellar activity and pulsation, and to set constraints on the planetary temperature–pressure structure and thus on the energetics possibly driving atmospheric escape. A complete orbital phase coverage of WASP-33b with high-resolution spectroscopic (and spectro-polarimetric) observations could help us to understand the nature of the pre-transit signal.

AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey from the ground. The refined orbital period of AU Mic b is 8.462995 ± 0.000003 d, whereas the stellar rotational period is Prot = 4.8367 ± 0.0006 d. The two periods indicate a 7:4 spin–orbit commensurability at a precision of 0.1%. Therefore, all transits are observed in front of one of the four possible stellar central longitudes. This is strongly supported by the observation that the same complex star-spot pattern is seen in the second and third CHEOPS visits that were separated by four orbits (and seven stellar rotations). Using a bootstrap analysis we find that flares and star spots reduce the accuracy of transit parameters by up to 10% in the planet-to-star radius ratio and the accuracy on transit time by 3–4 min. Nevertheless, occulted stellar spot features independently confirm the presence of transit timing variations (TTVs) with an amplitude of at least 4 min. We find that the outer companion, AU Mic c, may cause the observed TTVs.

Aims. We present a novel method for studying the thermal emission of exoplanets as a function of orbital phase at very high spectral resolution, and use it to investigate the climate of the ultra-hot Jupiter KELT-9b. Methods. We combine three nights of HARPS-N and two nights of CARMENES optical spectra, covering orbital phases between quadratures (0.25 < ϕ < 0.75), when the planet shows its day-side hemisphere with different geometries. We co-add the signal of thousands of Fe i lines through cross-correlation, which we map to a likelihood function. We investigate the phase-dependence of two separate observable quantities, namely (i) the line depths of Fe i and (ii) their Doppler shifts, introducing a new method that exploits the very high spectral resolution of our observations. Results. We confirm a previous detection of Fe i emission, and demonstrate a precision of 0.5 km s −1 on the orbital properties of KELT-9b when combining all nights of observations. By studying the phase-resolved Doppler shift of Fe i lines, we detect an anomaly in the planet's orbital radial velocity well-fitted with a slightly eccentric orbital solution (e = 0.016 ± 0.003, ω = 150 +13 • −11 , 5σ preference). However, we argue that this anomaly is caused by atmospheric circulation patterns, and can be explained if neutral iron gas is advected by day-to-night atmospheric wind flows of the order of a few km s −1 . We additionally show that the Fe i emission line depths are symmetric around the substellar point within 10 • (2σ), possibly indicating the lack of a large hot-spot offset at the altitude probed by neutral iron emission lines. Finally, we do not obtain a significant preference for models with a strong phase-dependence of the Fe i emission line strength. We show that these results are qualitatively compatible with predictions from general circulation models (GCMs) for ultra-hot Jupiter planets. Conclusions. Very high-resolution spectroscopy phase curves are of sufficient sensitivity to reveal a phase dependence in both the line depths and their Doppler shifts throughout the orbit. They constitute an under-exploited treasure trove of information that is highly complementary to space-based phase curves obtained with HST and JWST, and open a new window onto the still poorly understood climate and atmospheric structure of the hottest planets known to date.

The study of exoplanets and especially their atmospheres can reveal key insights on their evolution by identifying specific atmospheric species. For such atmospheric investigations, high-resolution transmission spectroscopy has shown great success, especially for Jupiter-type planets. Towards the atmospheric characterization of smaller planets, the super-Earth exoplanet 55 Cnc e is one of the most promising terrestrial exoplanets studied to date. Here, we present a high-resolution spectroscopic transit observation of this planet, acquired with the PEPSI instrument at the Large Binocular Telescope. Assuming the presence of Earth-like crust species on the surface of 55 Cnc e, from which a possible silicate-vapor atmosphere could have originated, we search in its transmission spectrum for absorption of various atomic and ionized species such as Fe , Fe +, Ca , Ca +, Mg  and K , among others. Not finding absorption for any of the investigated species, we are able to set absorption limits with a median value of 1.9 × RP. In conclusion, we do not find evidence of a widely extended silicate envelope on this super-Earth reaching several planetary radii.