Context. Clouds are ubiquitous in exoplanet atmospheres and they represent a challenge for the model interpretation of their spectra. When generating a large number of model spectra, complex cloud models often prove too costly numerically, whereas more efficient models may be overly simplified. Aims. We aim to constrain the atmospheric properties of the directly imaged planet HR 8799e with a free retrieval approach. Methods. We used our radiative transfer code petitRADTRANS for generating the spectra, which we coupled to the PyMultiNest tool. We added the effect of multiple scattering which is important for treating clouds. Two cloud model parameterizations are tested: the first incorporates the mixing and settling of condensates, the second simply parameterizes the functional form of the opacity. Results. In mock retrievals, using an inadequate cloud model may result in atmospheres that are more isothermal and less cloudy than the input. Applying our framework on observations of HR 8799e made with the GPI, SPHERE, and GRAVITY, we find a cloudy atmosphere governed by disequilibrium chemistry, confirming previous analyses. We retrieve that C/O = 0.60−0.08+0.07. Other models have not yet produced a well constrained C/O value for this planet. The retrieved C/O values of both cloud models are consistent, while leading to different atmospheric structures: either cloudy or more isothermal and less cloudy. Fitting the observations with the self-consistent Exo-REM model leads to comparable results, without constraining C/O. Conclusions. With data from the most sensitive instruments, retrieval analyses of directly imaged planets are possible. The inferred C/O ratio of HR 8799e is independent of the cloud model and thus appears to be a robust. This C/O is consistent with stellar, which could indicate that the HR 8799e formed outside the CO2 or CO iceline. As it is the innermost planet of the system, this constraint could apply to all HR 8799 planets.

We have used the HARPS-North high resolution spectrograph (R = 115 000) at TNG to observe one transit of the highly irradiated planet MASCARA-2b/KELT-20b. Using only one transit observation, we are able to clearly resolve the spectral features of the atomic sodium (Na I) doublet and the Hα line in its atmosphere, which are corroborated with the transmission calculated from their respective transmission light curves. In particular, we resolve two spectral features centered on the atomic sodium (Na I) doublet position with an averaged absorption depth of 0.17±0.03% for a 0.75 Å bandwidth, with line contrasts of 0.44±0.11% (D2) and 0.37±0.08% (D1). The Na I transmission light curves have been also computed, showing a large Rossiter-McLaughlin (RM) effect, with a 0.20 ± 0.05% Na I transit absorption for a 0.75 Å passband, consistent with the absorption depth value measured from the final transmission spectrum. We observe a second feature centered on the Hα line with 0.6 ± 0.1% contrast, and an absorption depth of 0.59 ± 0.08% for a 0.75 Å passband, with consistent absorptions in its transmission light curves, which corresponds to an effective radius of R λ /R P = 1.20±0.04. While S/N of the final transmission spectrum is not sufficient to adjust different temperature profiles to the lines, we find that higher temperatures than the equilibrium (T eq = 2260 ± 50 K) are needed to explain the lines contrast. Particularly, we find that the Na I lines core require a temperature of T = 4210 ± 180 K and that Hα requires a temperature of T = 4330 ± 520 K. MASCARA-2b, like other planets orbiting A-type stars, receives a large amount of UV energy from its host star. This energy excites the atomic hydrogen and produces Hα absorption, leading to the expansion and abrasion of the atmosphere. The study of other Balmer lines in the transmission spectrum would allow the determination of the atmospheric temperature profile and the calculation of the lifetime of the atmosphere with escape rate measurements. In the case of MASCARA-2b, residual features are observed in the H β and H γ lines, but they are not statistically significant. More transit observations are needed to confirm our findings in Na I and Hα, and to build up enough S/N to explore the presence of H β and H γ planetary absorptions.

We report on the performance of a vector apodizing phase plate coronagraph that operates over a wavelength range of 2-5 μmand is installed in MagAO/Clio2 at the 6.5 m Magellan Clay telescope at Las Campanas Observatory, Chile. The coronagraph manipulates the phase in the pupil to produce three beams yielding two coronagraphic point-spread functions (PSFs) and one faint leakage PSF. The phase pattern is imposed through the inherently achromatic geometric phase, enabled by liquid crystal technology and polarization techniques. The coronagraphic optic is manufactured using a direct-write technique for precise control of the liquid crystal patternand multitwist retarders for achromatization. By integrating a linear phase ramp to the coronagraphic phase pattern, two separated coronagraphic PSFs are created with a single pupil-plane optic, which makes it robust and easy to install in existing telescopes. The two coronagraphic PSFs contain a 180°dark hole on each side of a star, and these complementary copies of the star are used to correct the seeing halo close to the star. To characterize the coronagraph, we collected a data set of a bright (m L =0-1) nearby star with ∼1.5 hr of observing time. By rotating and optimally scaling one PSFand subtracting it from the other PSF, we see a contrast improvement by 1.46 magnitudes at l D 3.5. With regular angular differential imaging at 3.9 μm, the MagAO vector apodizing phase plate coronagraph delivers a s D 5 mag contrast of 8.3 (= -10 3.3 ) at 2 l Dand 12.2 (= -10 4.8 ) at l D 3.5.

Context. Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct detection is more sensitive to planets orbiting at a large distance from their host star. This dichotomy makes it difficult to combine the two techniques on a single target at once. Aims. Simultaneous measurements made by direct and indirect techniques offer the possibility of determining the mass and luminosity of planets and a method of testing formation models. Here, we aim to show how long-baseline interferometric observations guided by radial-velocity can be used in such a way. Methods. We observed the recently-discovered giant planet β Pictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer. Results. This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature of T = 1250 ± 50 K and a dynamical mass of M = 8.2 ± 0.8 MJup. At 18.5 ± 2.5 Myr, this puts β Pic c close to a ‘hot start’ track, which is usually associated with formation via disk instability. Conversely, the planet orbits at a distance of 2.7 au, which is too close for disk instability to occur. The low apparent magnitude (MK = 14.3 ± 0.1) favours a core accretion scenario. Conclusions. We suggest that this apparent contradiction is a sign of hot core accretion, for example, due to the mass of the planetary core or the existence of a high-temperature accretion shock during formation.