The radii of small exoplanets form two populations, super-Earths and sub-Neptunes, separated by a gap known as the radius valley. This feature could be produced by the removal of atmospheres by stellar or internal heating or by the lack of an initial envelope. We used transit photometry and radial velocity measurements to detect and characterize four exoplanets orbiting LHS 1903, a red dwarf star in the Milky Way's thick disk. These four planets have orbital periods ranging from 2.2 to 29.3 days and span the radius valley within a single planetary system. The derived densities indicate that LHS 1903 b is rocky, whereas LHS 1903 c and LHS 1903 d have extended atmospheres. The most distant planet from the host star, LHS 1903 e, has no gaseous envelope, indicating that it formed from gas-depleted material.

Understanding the earliest stage of star and planet formation requires detailed observations to address the connection and interplay between the accretion, outflow, and disk evolution. We present results from the observations of the low luminosity (Lbol similar to 0.2 L circle dot) and mass (M* similar to 0.15 M circle dot) Class 0 protostar IRAS 16253-2429, conducted as part of the eDisk Atacama Large Millimeter/submillimeter Array (ALMA) large program and the JWST cycle-1 GO Investigating Protostellar Accretion program. Observations reveal a wide hourglass-shaped continuum cavity traced in scattered light (at <= 5 mu m), with a brighter, extended northern side. We detect 15 pure rotational H2 transitions (Eup: 1015-21411 K), revealing a wide-angle molecular outflow. The outflow width (as traced in H2 0-0 S(11)) at the protostellar location measures <= 35 au, slightly larger than the dust and Keplerian disk diameters (similar to 30 au) but wider than the 20-23 au jet width in [Fe II]. The opening angle narrows from 40 degrees to 35 degrees for the low-J H2 lines (up to S(5)) and the cold gas component (ALMA 12CO) to similar to 28 degrees-19 degrees for the high-J H2 lines (S(7)-S(11)). Position-velocity diagrams of H2 reveal higher velocities for higher Eup, ranging from 12.5 km s-1 for H2 0-0 S(1) and S(2) to 28.5 km s-1 for H2 0-0 S(5) and S(7) with respect to the mean flow velocity. The nested excitation and velocity structure of the collimated jet and wide-angle wind suggest a magnetohydrodynamic wind as a likely launching mechanism, similar to the findings in other protostars and Class II sources. The lower velocity millimeter CO may be gas from the infalling envelope accelerated outwards by the wide-angle wind along the cavity walls.

Jets and outflows are ubiquitous phenomena associated with the formation of young stellar objects (YSOs). They play a crucial role in removing angular momentum from the accreting system and in regulating star-formation efficiency. Theoretical studies and observations with ALMA and VLA have shown that jets and winds may have a crucial role in promoting dust growth in the envelope-disc system and in shaping the physical and chemical properties of the surrounding environment. Despite these significant advances, many fundamental questions remain unanswered regarding the acceleration, collimation, and chemical impact of jets and outflows from YSOs. The SKA-project will overcome the limitations of current mm/cm-facilities by enabling high-angular resolution and high-sensitivity cm-observations, crucial for probing jets/outflows near YSOs. Radio recombination lines, combined with proper motions, offer a unique opportunity to study the 3D-kinematics of jets. Non-thermal linearly polarised synchrotron emission will allow measuring magnetic field strength and morphology at unprecedented scales of a few au. Observations of dust emission in outflow cavities will allow studying how dust grows and is eventually transported from the disc to the envelope and back. Finally, the SKA-project will allow exploring the dust composition and chemical enrichment in shocks, where sputtering/shattering of grains cause the release of their mantles and refractory cores in the gas-phase. Complementary to ALMA's detection of simple and complex organic molecules, the SKAO will probe, for the first time, long carbon chains/rings, several Cl-, Al-, Mg-, and other metal-bearing species (missed by current sub-mm facilities).

Aims. We search for radio emission from star-planet interactions in the M dwarf system GJ 486, which hosts an Earth-like planet. Methods. We observed the GJ 486 system with the upgraded Giant Metrewave Radio Telescope (uGMRT) from 550 to 750 MHz in nine different epochs between October 2021 and February 2022, covering almost all orbital phases of GJ 486b from different orbital cycles. We obtained radio images and dynamic spectra of the total and circularly polarized intensity for each individual epoch. Results. We did not detect any quiescent radio emission in any epoch above 3 sigma. Similarly, we did not detect any bursty emission in our dynamic spectra. Conclusions. While we cannot completely rule out that the absence of a radio detection is due to time variability of the radio emission or to the maximum electron-cyclotron maser emission being below our observing range, these cases seem unlikely. We discuss two possible scenarios: an intrinsic dim radio signal and, alternatively, a situation where the anisotropic beamed emission is pointed away from the observer. If the non-detection of radio emission from the star-planet interaction in GJ 486 is due to an intrinsically dim signal, this implies that independent of whether the planet is magnetized or not, the mass-loss rate is small (M star less than or similar to 0.3 M-circle dot) and that, concomitantly, the efficiency of the conversion of the Poynting flux into radio emission must be low (beta less than or similar to 10(-3)). Free-free absorption effects are negligible, given the high value of the coronal temperature. Finally, if the anisotropic beaming pointed away from the observer, this would imply that GJ 486 has very low values of magnetic obliquity and inclination.

The composition of protoplanetary disks, and hence the initial conditions of planet formation, may be strongly influenced by the infall and thermal processing of material during the protostellar phase. The composition of dust and ice in protostellar envelopes, shaped by energetic processes driven by the protostar, serves as the fundamental building material for planets and complex organic molecules. As part of the JWST General Observers program, “Investigating Protostellar Accretion,” we observed an intermediate-mass protostar HOPS 370 (OMC2-FIR3) using NIRSpec integral field unit and Mid-Infrared Instrument medium-resolution spectroscopy. This study presents the gas and ice phase chemical inventory revealed with the JWST in the spectral range of ∼2.9–28 μ m and explores the spatial variation of volatile ice species in the protostellar envelope. We find evidence for the thermal processing of ice species throughout the inner envelope. We present the first high-spatial resolution (∼80 au) maps of key volatile ice species H _2 O, CO _2 , ^13 CO _2 , CO, and OCN ^− , which reveal a highly structured and inhomogeneous density distribution of the protostellar envelope, with a deficiency of ice column density that coincides with the jet/outflow shocked knots. Further, we observe high relative crystallinity of H _2 O ice around the shocked knot seen in the H _2 and OH wind/outflow, which can be explained by a lack of outer colder material in the envelope along the line of sight due to the irregular structure of the envelope. These observations show clear evidence of thermal processing of the ices in the inner envelope, close to the outflow cavity walls, heated by the luminous protostar.

Stars such as the Sun expel their outer layers and form planetary nebulae (PNe) as they evolve into white dwarfs. PNe exhibit diverse morphologies, the origins of which are not fully understood. PNe with OH (OHPNe) and H 2 O (H 2 OPNe) masers are thought to be nascent PNe. However, the number of known OHPNe and H 2 OPNe remains small, and only in eight cases has the position of the maser emission been found to coincide with the PN, using the high astrometric accuracy of interferometric observations. In order to identify more OHPNe and H 2 OPNe, we used public databases and our own ATCA/VLA observations to match the positions of OH and H 2 O masers with known PNe and radio continuum emitters, considering radio continuum emission as a possible tracer of the photoionized gas that characterizes PNe. Here we report the confirmation of positional coincidence of maser emission with one more PN, and 12 PN candidates. Moreover, we have confirmed three evolved stars as ‘water fountains’ (WFs) hosting H 2 O masers. These WFs are associated with radio continuum emission, but their possible nature as PNe has not yet been confirmed. Although a final characterization of maser-emitting PNe as a group still requires confirmation of more objects, their distribution in the infrared color-color diagrams suggests that they are a heterogeneous group of PNe. In particular, the new OHPN IRAS 07027–7934 has been reported to contain a late [WC]-type central star, while the maser emission implies an O-rich envelope. This property is found in only one other known maser-emitting PN, although we found evidence that other confirmed and candidate OHPNe may also have mixed chemistry, since they show emission from polycyclic aromatic hydrocarbons. The new WF IRAS 18443–0231 shows radio continuum that is dominated by strong and variable non-thermal emission, as in magnetized outflows.

Nitrogen-bearing complex organic molecules have been commonly detected in the gas phase but not yet in interstellar ices. This has led to the long-standing question of whether these molecules form in the gas phase or in ices. James Webb Space Telescope (JWST) offers the sensitivity, spectral resolution, and wavelength coverage needed to detect them in ices and investigate whether their abundance ratios are similar in gas and ice. We report the first tentative detection of CH_3CN, C_2H_5CN, and the simple molecule, N_2O, based on the CN-stretch band in interstellar ices toward three (HOPS 153, HOPS 370, and IRAS 20126+4104) out of the five protostellar systems observed as part of the Investigating Protostellar Accretion (IPA) GO program with JWST-NIRSpec. We also provide upper limits for the two other sources with smaller luminosities in the sample. We detect OCN^- in the ices of all sources with typical CH_3CN/OCN^- ratios of around 1. Ice and gas column density ratios of the nitrogen-bearing species with respect to each other are better matched than those with respect to methanol, which are a factor of ∼5 larger in the ices than the gas. We attribute the elevated ice column densities with respect to methanol to the difference in snowline locations of nitrogen-bearing molecules and of methanol, biasing the gas-phase observations toward fewer nitrogen-bearing molecules. Moreover, we find tentative evidence for enhancement of OCN^-, CH_3CN, and C_2H_5CN in warmer ices, although formation of these molecules likely starts along with methanol in the cold prestellar phase. Future surveys combining NIRSpec and MIRI, and additional laboratory spectroscopic measurements of C_2H_5CN ice, are necessary for robust detection and conclusions on the formation history of complex cyanides.

Context. Observational constraints on dust properties in protoplanetary disks are key to better understanding disk evolution, their dynamics, and the pathway to planet formation, but also surface chemistry, the main driver of chemical complexity. Aims. We continue our exploration of the protoplanetary disk around AB Aur by characterizing its dust properties at different millimeter wavelengths. Methods. We present new ALMA observations at 2.2 mm and VLA observations at 6.8 mm. Together with previous ALMA and NOEMA observations at 0.87 and 1.1 mm, these new observations are used to compute global spectral index profiles as well as spectral index maps to probe the dust properties throughout the disk. On the interpretation side, we present the results of a simple isothermal slab model to help constrain dust properties along the non-axisymmetric ring of continuum emission outside the millimeter cavity. We also present new results of dust radiative transfer calculations based on a disk-planet hydrodynamical simulation to explain how the azimuthal contrast ratio of the ring emission varies with millimeter wavelength. Results. The spectral energy distribution and the radial profiles of the spectral index indicate that the radiation from the compact source towards the center is not dominated by dust thermal emission, but most likely by free-free emission originating in the radio jet; it constitutes 93% of the emission at 6.8 mm, and 37% at 0.87 mm. The protoplanetary disk has a typical spectral index of 2.3, computed using the 0.87, 1.1, and 2.2 mm bands. We estimate a dust disk mass of 8 x 10(-5) M-circle dot which, assuming a mean gas-to-dust ratio of 40, gives a total disk mass of 3.2 x 10(-3) M-circle dot. The azimuthal contrast ratio of the ring outside the millimeter cavity is smaller at 2.2 mm than at 1.1 mm, in agreement with previous findings. The VLA image shows several knots of 5 sigma emission all along the ring, which, with the help of our dust radiative transfer calculations, are consistent with the ring emission being nearly axisymmetric at that wavelength. The decrease in the azimuthal contrast ratio of the ring emission from 0.87 to 6.8 mm can be explained by a dust-losing decaying vortex at the outer edge of a planet gap.

Investigating Protostellar Accretion is a Cycle 1 JWST program using the NIRSpec+MIRI integral field units to obtain 2.9-28 mu m spectral cubes of five young protostars with luminosities of 0.2-10,000 L-circle dot in their primary accretion phase. This paper introduces the NIRSpec 2.9-5.3 mu m data of the inner 840-9000 au with spatial resolutions from 28 to 300 au. The spectra show rising continuum emission; deep ice absorption; emission from H-2, H i, and [Fe ii]; and the CO fundamental series in emission and absorption. Maps of the continuum emission show scattered light cavities for all five protostars. In the cavities, collimated jets are detected in [Fe ii] for the four <320 L-circle dot protostars, two of which are additionally traced in Br alpha. Knots of [Fe ii] emission are detected toward the most luminous protostar, and knots of [Fe ii] emission with dynamical times of <30 yr are found in the jets of the others. While only one jet is traced in H-2, knots of H-2 and CO are detected in the jets of four protostars. H-2 is seen extending through the cavities, showing that they are filled by warm molecular gas. Bright H-2 emission is seen along the walls of a single cavity, while in three cavities narrow shells of H-2 emission are found, one of which has an [Fe ii] knot at its apex. These data show cavities containing collimated jets traced in atomic/ionic gas surrounded by warm molecular gas in a wide-angle wind and/or gas accelerated by bow shocks in the jets.

Observations of low-mass stars have frequently shown a disagreement between observed stellar radii and radii predicted by theoretical stellar structure models. This “radius inflation” problem could have an impact on both stellar and exoplanetary science. We present the final results of our observation programme with the CHEOPS satellite to obtain high-precision light curves of eclipsing binaries with low mass stellar companions (EBLMs). Combined with the spectroscopic orbits of the solar-type companion, we can derive the masses, radii and effective temperatures of 23 M-dwarf stars. We use the PYCHEOPS data analysis software to analyse their primary and secondary occultations. For all but one target, we also perform analyses with TESS light curves for comparison. We have assessed the impact of starspot-induced variation on our derived parameters and account for this in our radius and effective temperature uncertainties using simulated light curves. We observe trends for inflation with both metallicity and orbital separation. We also observe a strong trend in the difference between theoretical and observational effective temperatures with metallicity. There is no such trend with orbital separation. These results are not consistent with the idea that observed inflation in stellar radius combines with lower effective temperature to preserve the luminosity predicted by low-mass stellar models. Our EBLM systems are high-quality and homogeneous measurements that can be used in further studies into radius inflation.

Context. Multiwavelength photometry of the secondary eclipses of extrasolar planets is able to disentangle the reflected and thermally emitted light radiated from the planetary dayside. Based on this, we can measure the planetary geometric albedo Ag, which is an indicator of the presence of clouds in the atmosphere, and the recirculation efficiency ϵ, which quantifies the energy transport within the atmosphere. Aims. We measure Ag and ϵ for the planet WASP-178 b, a highly irradiated giant planet with an estimated equilibrium temperature of 2450 K. Methods. We analyzed archival spectra and the light curves collected by CHEOPS and TESS to characterize the host WASP-178, refine the ephemeris of the system, and measure the eclipse depth in the passbands of the two telescopes. Results. We measured a marginally significant eclipse depth of 70 ± 40 ppm in the TESS passband, and a statistically significant depth of 70 ± 20 ppm in the CHEOPS passband. Conclusions. Combining the eclipse-depth measurement in the CHEOPS (λeff = 6300 Å) and TESS (λeff = 8000 Å) passbands, we constrained the dayside brightness temperature of WASP-178 b in the 2250–2800 K interval. The geometric albedo 0.1< Ag<0.35 generally supports the picture that giant planets are poorly reflective, while the recirculation efficiency ϵ >0.7 makes WASP-178 b an interesting laboratory for testing the current heat-recirculation models.

The structure and composition of simple ices can be severely modified during stellar evolution by protostellar heating. Key to understanding the involved processes are thermal and chemical tracers that can be used to diagnose the history and environment of the ice. The 15.2 µm bending mode of 12CO2 in particular has proven to be a valuable tracer of ice heating events but suffers from grain shape and size effects. A viable alternative tracer is the weaker 13CO2 isotopologue band at 4.39 µm, which has now become accessible at high S/N with the James Webb Space Telescope (JWST). In this study, we present JWST NIRSpec observations of 13CO2 ice in five deeply embedded Class 0 sources that span a wide range in masses and luminosities (0.2–104 L⊙) taken as part of the Investigating Protostellar Accretion Across the Mass Spectrum (IPA) program. The band profiles vary significantly depending on the source, with the most luminous sources showing a distinct narrow peak at 4.38 µm. We first applied a phenomenological approach with which we demonstrate that a minimum of three to four Gaussian profiles are needed to fit the absorption feature of 13CO2. We then combined these findings with laboratory data and show that a 15.2 µm 12CO2 bending-mode-inspired five-component decomposition can be applied to the isotopologue band, with each component representative of CO2 ice in a specific molecular environment. The final solution consists of cold mixtures of CO2 with CH3OH, H2O, and CO as well as segregated heated pure CO2 ice at 80 K. Our results are in agreement with previous studies of the 12CO2 ice band, further confirming that 13CO2 is a useful alternative tracer of protostellar heating and ice composition. We also propose an alternative solution consisting only of heated mixtures of CO2:CH3OH and CO2:H2O ices and warm pure CO2 ice at 80 K (i.e., no cold CO2 ices) for decomposing the ice profiles of HOPS 370 and IRAS 20126, the two most luminous sources in our sample that show strong evidence of ice heating resulting in ice segregation.

Investigating Protostellar Accretion (IPA) is a JWST Cycle 1 GO program that uses NIRSpec integral field units and MIRI Medium Resolution Spectrograph to obtain 2.9–28 μ m spectral cubes of young, deeply embedded protostars with luminosities of 0.2–10,000 L _⊙ and central masses of 0.15–12 M _⊙ . In this Letter, we report the discovery of a highly collimated atomic jet from the Class 0 protostar IRAS 16253−2429, the lowest-luminosity source ( L _bol = 0.2 L _⊙ ) in the IPA program. The collimated jet is detected in multiple [Fe ii ] lines and [Ne ii ], [Ni ii ], and H i lines but not in molecular emission. The atomic jet has a velocity of about 169 ± 15 km s ^−1 , after correcting for inclination. The width of the jet increases with distance from the central protostar from 23 to 60 au, corresponding to an opening angle of 2.°6 ± 0.°5. By comparing the measured flux ratios of various fine-structure lines to those predicted by simple shock models, we derive a shock speed of 54 km s ^−1 and a preshock density of 2.0 × 10 ^3 cm ^−3 at the base of the jet. From these quantities and using a suite of jet models and extinction laws, we compute a mass-loss rate between 0.4 and 1.1 ×10 ^−10 M _⊙ yr ^−1 . The low mass-loss rate is consistent with simultaneous measurements of low mass accretion rate (2.4 ± 0.8 × 10 ^−9 M _⊙ yr ^−1 ) for IRAS 16253−2429 from JWST observations, indicating that the protostar is in a quiescent accretion phase. Our results demonstrate that very low-mass protostars can drive highly collimated, atomic jets, even during the quiescent phase.

We aim to constrain the internal structure and composition of HD 15337 b and c, two short-period planets situated on opposite sides of the radius valley, using new transit photometry and radial velocity data. We acquire 6 new transit visits with the CHaracterising ExOPlanet Satellite (CHEOPS) and 32 new radial velocity measurements from the High Accuracy Radial Velocity Planet Searcher (HARPS) to improve the accuracy of the mass and radius estimates for both planets. We reanalyse light curves from TESS sectors 3 and 4 and analyse new data from sector 30, correcting for long-term stellar activity. Subsequently, we perform a joint fit of the TESS and CHEOPS light curves, and all available RV data from HARPS and the Planet Finder Spectrograph (PFS). Our model fits the planetary signals, the stellar activity signal and the instrumental decorrelation model for the CHEOPS data simultaneously. The stellar activity was modelled using a Gaussian-process regression on both the RV and activity indicators. We finally employ a Bayesian retrieval code to determine the internal composition and structure of the planets. We derive updated and highly precise parameters for the HD 15337 system. Our improved precision on the planetary parameters makes HD 15337 b one of the most precisely characterised rocky exoplanets, with radius and mass measurements achieving a precision better than 2\% and 7\%, respectively. We are able to improve the precision of the radius measurement of HD 15337 c to 3\%. Our results imply that the composition of HD 15337 b is predominantly rocky, while HD 15337 c exhibits a gas envelope with a mass of at least $0.01\ M_\oplus$.Our results lay the groundwork for future studies, which can further unravel the atmospheric evolution of these exoplanets and give new insights into their composition and formation history and the causes behind the radius gap.

Using the MIRI/MRS spectrometer on JWST, we have detected pure rotational, suprathermal OH emissions from the vicinity of the intermediate-mass protostar HOPS 370 (OMC2/FIR3). These emissions are observed from shocked knots in a jet/outflow, and originate in states of rotational quantum number as high as 46 that possess excitation energies as large as E-U/k=4.65x10(4) K. The relative strengths of the observed OH lines provide a powerful diagnostic of the ultraviolet radiation field in a heavily-extinguished region (A(V)similar to 10-20) where direct UV observations are impossible. To high precision, the OH line strengths are consistent with a picture in which the suprathermal OH states are populated following the photodissociation of water in its (B) over bar - X band by ultraviolet radiation produced by fast (similar to 80kms(-1)) shocks along the jet. The observed dominance of emission from symmetric (A ') OH states over that from antisymmetric (A '') states provides a distinctive signature of this particular population mechanism. Moreover, the variation of intensity with rotational quantum number suggests specifically that Ly alpha radiation is responsible for the photodissociation of water, an alternative model with photodissociation by a 10(4) K blackbody being disfavored at a high level of significance. Using measurements of the Br alpha flux to estimate the Ly alpha production rate, we find that similar to 4% of the Ly alpha photons are absorbed by water. Combined with direct measurements of water emissions in the nu(2)=1-0 band, the OH observations promise to provide key constraints on future models for the diffusion of Ly alpha photons in the vicinity of a shock front.

We present the discovery and characterization of two warm mini-Neptunes transiting the K3V star TOI-815 in a K-M binary system. Analysis of its spectra and rotation period reveal the star to be young, with an age of 200(-200)(+400) Myr. TOI-815b has a 11.2-day period and a radius of 2.94 +/- 0.05 R-circle plus with transits observed by TESS, CHEOPS, ASTEP, and LCOGT. The outer planet, TOI-815c, has a radius of 2.62 +/- 0.10 R-circle plus, based on observations of three nonconsecutive transits with TESS; targeted CHEOPS photometry and radial velocity follow-up with ESPRESSO were required to confirm the 35-day period. ESPRESSO confirmed the planetary nature of both planets and measured masses of 7.6 +/- 1.5 M-circle plus (rho(P) = 1.64(-0.31)(+0.33) g cm(-3)) and 23.5 +/- 2.4 M. (rho(P) = 7.2(-1.0)(+1.1)g cm(-3)), respectively. Thus, the planets have very different masses, which is unusual for compact multi-planet systems. Moreover, our statistical analysis of mini-Neptunes orbiting FGK stars suggests that weakly irradiated planets tend to have higher bulk densities compared to those undergoing strong irradiation. This could be ascribed to their cooler atmospheres, which are more compressed and denser. Internal structure modeling of TOI-815b suggests it likely has a H-He atmosphere that constitutes a few percent of the total planet mass, or higher if the planet is assumed to have no water. In contrast, the measured mass and radius of TOI-815c can be explained without invoking any atmosphere, challenging planetary formation theories. Finally, we infer from our measurements that the star is viewed close to pole-on, which implies a spin-orbit misalignment at the 3 sigma level. This emphasizes the peculiarity of the system's orbital architecture, and probably hints at an eventful dynamical history.

Context. M-dwarf stars are the most common of potential exoplanet host stars in the Galaxy. It is therefore very important to understand planetary systems orbiting such stars and to determine the physical parameters of such planets with high precision. Also with the launch of the James Webb Space Telescope (JWST) the observation of atmospheric parameters of planets orbiting these stars has begun. It is therefore required to determine properties of potential targets. Aims. Two planets around the red dwarf TOI-776 were detected by TESS. The objective of our study was to use transit observations obtained by the CHEOPS space mission to improve the current precision of the planetary radii, as well as additional radial velocity (RV) data in order to improve mass estimates of the two planets. Using these quantities, we wanted to derive the bulk densities of those planets, improving the precision in earlier results, and use this information to put them in context of other exoplanetary systems involving very low mass stars. Methods. Utilizing new transit data from the CHEOPS satellite and its photometric telescope, we obtained very high precision planetary transit measurements. Interpretation of these provides updated planetary radii, along with other system parameters. A concurrent ESO large observing program using the high precision spectrograph HARPS has doubled the available radial velocity data. Calculating the power spectrum of a number of stellar activity indices we update the previously estimated stellar rotation period to a lower value. Results. The CHEOPS data provide precise transit depths of 909 and 1177 ppm translating into radii of R b = 1.798 −0.077 +0.078 R ⊕ and R c = 2.047 −0.078 +0.081 R ⊕ , respectively. Our interpretation of the radial velocities and activity indicator time series data estimates a stellar rotation period for this early M dwarf of ~21.1 days. A further multi-dimensional Gaussian process approach confirm this new estimate. By performing a Skew-Normal (SN) fit onto the Cross Correlation Functions we extracted the RV data and the activity indicators to estimate the planetary masses, obtaining M b = 5.0 −1.6 +1.6 M ⊕ and M c = 6.9 −2.5 +2.6 M ⊕ . Conclusions. We improve the precision in planetary radius for TOI-776 b and c by a factor of more than two. Our data and modelling give us parameters of both bodies consistent with mini-Neptunes, albeit with a relatively high density. The stellar activity of TOI-776 is found to have increased by a factor larger than 2 since the last set of observations.

Context. HR 10 has only recently been identified as a binary system. Previously thought to be an A-type shell star, it appears that both components are fast-rotating A-type stars, each presenting a circumstellar envelope. Although showing complex photometric variability, spectroscopic observations of the metallic absorption lines reveal variation explained by the binarity, but not indicative of debris-disc inhomogeneities or sublimating exocomets. On the other hand, the properties of the two stars make them potential delta Scuti pulsators. Aims. The system has been observed in two sectors by the TESS satellite, and was the target of three observing visits by CHEOPS. Thanks to these new data, we aim to further characterise the stellar properties of the two components. In particular, we aim to decipher the extent to which the photometric variability can be attributed to a stellar origin. In complement, we searched in the lightcurves for transient-type events that could reveal debris discs or exocomets. Methods. We analysed the photometric variability of both the TESS and CHEOPS datasets in detail. We first performed a frequency analysis to identify and list all the periodic signals that may be related to stellar oscillations or surface variability. The signals identified as resulting from the stellar variability were then removed from the lightcurves in order to search for transient events in the residuals. Results. We report the detection of delta Scuti pulsations in both the TESS and CHEOPS data, but we cannot definitively identify which of the components is the pulsating star. In both datasets, we find flicker noise with the characteristics of a stellar granulation signal. However, it remains difficult to firmly attribute it to actual stellar granulation from convection, given the very thin surface convective zones predicted for both stars. Finally, we report probable detection of transient events in the CHEOPS data, without clear evidence of their origin.

Nitrogen-bearing complex organic molecules have been commonly detected in the gas phase but not yet in interstellar ices. This has led to the long-standing question of whether these molecules form in the gas phase or in ices. The James Webb Space Telescope (JWST) offers the sensitivity, spectral resolution, and wavelength coverage needed to detect them in ices and investigate whether their abundance ratios are similar in gas and ice. We report the first tentative detection of CH3CN, C2H5CN and the simple molecule, N2O, based on the CN-stretch band in interstellar ices toward three (HOPS 153, HOPS 370, and IRAS 20126+4104) out of the five protostellar systems observed as part of the Investigating Protostellar Accretion (IPA) GO program with JWST-NIRSpec. We also provide upper limits for the two other sources with smaller luminosities in the sample. We detect OCN- in the ices of all sources with typical CH3CN/OCN- ratios of around 1. Ice and gas column density ratios of the nitrogen-bearing species with respect to each other are better matched than those with respect to methanol, which are a factor of similar to 5 larger in the ices than the gas. We attribute the elevated ice column densities with respect to methanol to the difference in snowline locations of nitrogen-bearing molecules and of methanol, biasing the gas-phase observations toward fewer nitrogen-bearing molecules. Moreover, we find tentative evidence of the enhancement of OCN-, CH3CN, and C2H5CN in warmer ices; although, the formation of these molecules likely starts along with methanol in the cold prestellar phase. Future surveys combining NIRSpec and MIRI, and additional laboratory spectroscopic measurements of C2H5CN ice, are necessary for robust detection and conclusions on the formation history of complex cyanides.

Tidal orbital decay is suspected to occur especially for hot Jupiters, with the only observationally confirmed case of this being WASP-12 b. By examining this effect, information on the properties of the host star can be obtained using the so-called stellar modified tidal quality factor Q_*', which describes the efficiency with which kinetic energy of the planet is dissipated within the star. This can help to get information about the interior of the star. In this study, we aim to improve constraints on the tidal decay of the KELT-9, KELT-16 and WASP-4 systems, to find evidence for or against the presence of this particular effect. With this, we want to constrain each star's respective Q_*' value. In addition to that, we also aim to test the existence of the transit timing variations (TTVs) in the HD 97658 system, which previously favoured a quadratic trend with increasing orbital period. Making use of newly acquired photometric observations from CHEOPS and TESS, combined with archival transit and occultation data, we use Markov chain Monte Carlo (MCMC) algorithms to fit three models, a constant period model, an orbital decay model, and an apsidal precession model, to the data. We find that the KELT-9 system is best described by an apsidal precession model for now, with an orbital decay trend at over 2 σ being a possible solution as well. A Keplerian orbit model with a constant orbital period fits the transit timings of KELT-16 b the best due to the scatter and scale of their error bars. The WASP-4 system is represented the best by an orbital decay model at a 5 σ significance, although apsidal precession cannot be ruled out with the present data. For HD 97658 b, using recently acquired transit observations, we find no conclusive evidence for a previously suspected strong quadratic trend in the data.