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Abstract KELT-20b is a well-studied (T_eq = 2262 K) ultrahot Jupiter, but its multidimensional atmospheric structure remains unconstrained. We performed high-resolution cross-correlation transmission spectroscopy (HRCCTS) on a single-transit time series of KELT-20b, observed with the Potsdam Echelle Polarimetric and Spectroscopic Instrument on the Large Binocular Telescope. Upon combining nineteen in-transit exposures, we detect FeI(11.9σ) and FeII(23.7σ) and tentatively detect NaI(3.4σ) and CrI(3.3σ). The full-transit velocity offsets of the strongest absorbers are ΔV_FeI = −1.0 ± 0.7 km s⁻¹and ΔV_FeII = 0.0 ± 0.5 km s⁻¹, which are mostly inconsistent with previously published values for KELT-20b, although the previous measurements are mostly inconsistent with each other. By correcting for discrepant systemic velocity solutions of up to 1.7 km s⁻¹between studies, our FeIIoffset becomes consistent with previous measurements (≤1.7σ), while FeIremains significantly less blueshifted than in earlier studies (≥2.2−4.5σ). We propose a set of detection criteria to improve future reproducibility in HRCCTS work. Phase-resolving the FeIand FeIIabsorption signatures into eight orbital phase bins reveals distinct dynamical regimes: FeIIexhibits a strong phase-dependent blueshift from ingress to egress along with significant limb asymmetry, while FeIshows weaker signals and a more modest blueshift with phase. These patterns indicate day-to-night winds and suggest scale height differences are a significant driver of limb asymmetry in KELT-20b. 

ABSTRACT Ultra-hot Jupiters (UHJs) orbit close to their host stars and experience extreme conditions, making them important laboratories to explore atmospheric composition and dynamics. Transmission spectroscopy is a useful tool to reveal chemical species and their vertical and longitudinal distribution in the atmosphere. We use transmission spectra from the PEPSI (Potsdam Echelle Polarimetric and Spectroscopic Instrument) spectrograph on the Large Binocular Telescope to search for species and measure their time-resolved wind velocities in the atmosphere of TOI-1518 b. We detect Fe i at 7.8$$\sigma$$ and Fe ii at 8.9$$\sigma$$, and tentatively detect Cr i at 4.4$$\sigma$$ and Ni i at 4.0$$\sigma$$. The time-resolved wind velocities of Fe i show a velocity pattern that is consistent with the velocity pattern of Fe ii. TOI-1518 b joins a small sample of UHJs for which time-resolved wind velocities have been measured. 

Abstract We present five datasets of high-resolution optical emission spectra of the ultra-hot-Jupiter KELT-20 b with the PEPSI spectrograph. Using a Bayesian retrieval framework, we constrain its dayside pressure–temperature profile and abundances of Fe, Ni, and Ca, providing the first measurements for Ni and Ca for KELT-20 b in emission. We retrieve the preeclipse and posteclipse datasets separately (corresponding to the evening and morning sides, respectively), and compare the constraints on their thermal structures and chemical abundances. We constrain lower abundances in the pre-eclipse datasets compared to the posteclipse datasets. We interpret these results with an equilibrium chemistry model which suggests ∼10–30× supersolar refractory abundances. Due to the well-known degeneracy between absolute abundances and continuum opacities, the abundance ratios are more precise probes of the planetary abundances. Therefore we measure the abundance ratios [Ni/Fe] and [Ca/Fe] across these datasets and find they agree within 1σ. We constrain [Ni/Fe] to be consistent with solar within 2σ, and [Ca/Fe] to be 0.001–0.01× solar, not accounting for ionization. We compare these abundance ratios with literature results for KELT-20 b in transmission, and find they agree within 2σ, suggesting that even though the abundances vary significantly as a function of phase, the abundance ratios of these species remain relatively constant. We find a ∼100 K difference in temperature at the top of the thermal inversion, suggesting a hotter evening side than morning side and underscoring the importance of considering 3D effects when studying ultrahot Jupiters. 

Abstract Despite the wide range of planet–star (mis)alignments in the mature population of transiting exoplanets, the small number of known young transiting planets are nearly all aligned with the rotation axes of their host stars, as determined by the sky-projected obliquity angle. The small number of young systems with measured obliquities limits statistical conclusions. Here we determine the sky-projected obliquity (λ) of the 3 Myr transiting planet with a misaligned outer protoplanetary disk, TIDYE-1 b (IRAS 04125+2902b), using the Rossiter–McLaughlin (RM) effect. Our dataset lacks a pretransit baseline and ingress, complicating a blind RM fit. Instead, we use contemporaneous spectra and photometry from a mass-measurement campaign to model the stellar activity trend across the transit and provide an external prior on the velocity baseline. We determine $\mid \lambda \mid =11.8_{-5.0}^{+5.9}°$ . Combined with the published rotational velocity of the star, we find a true three-dimensional obliquity of $\psi =15.2_{-5.7}^{+7.3}°$ . Our result is consistent with an aligned orbit, suggesting the planet remains aligned to its star even though the outer disk is misaligned, though additional RM observations are needed to exclude the low-probability tail of misaligned (>30°) scenarios present in our posterior. 

ABSTRACT WASP-12 b is an ultra-hot Jupiter of special interest for atmospheric studies since it is on an inspiraling orbit in an extreme environment of intense radiation and circumstellar gas. Previously claimed detections of active mass-loss from this planet are controversial across the literature. To address this controversy, we obtain two new transit observations of WASP-12 b with the optical high-resolution PEPSI spectrograph on the Large Binocular Telescope. Contrary to previous work, we do not observe planetary H$$\alpha$$ absorption and rule out the amplitude of previously reported detections. Our non-detection may be limited by the sensitivity of our data or could indicate weaker mass-loss than suggested by previous studies. We conduct injection-recovery experiments to place constraints on the radial extent of WASP-12 b’s escaping atmosphere as probed by Balmer lines, but find that our data do not have the sensitivity to probe down to the planet’s Roche lobe. Using physically motivated models of atmospheric escape, we explore upper limit constraints on the planet’s mass-loss rate and deem the data quality in the wavelength regime of Balmer lines insufficient to determine a physically meaningful constraint. We also conduct a spectral survey of other optical absorbers to trace atmospheric circulation but detect no additional absorption. We conclude that previous claims of H$$\alpha$$ absorption from the atmosphere of WASP-12 b should be reevaluated. Given the anticipated line strength of Balmer/optical features, observing the atmosphere of this faint target will require stacking more observations even with the largest telescope facilities available. 

ABSTRACT Gut symbionts influence the physiology and behavior of their host, but the extent to which these effects scale to social behaviors is an emerging area of research. The use of the western honeybee (Apis mellifera) as a model enables researchers to investigate the gut microbiome and behavior at several levels of social organization. Insight into gut microbial effects at the societal level is critical for our understanding of how involved microbial symbionts are in host biology. In this Commentary, we discuss recent findings in honeybee gut microbiome research and synthesize these with knowledge of the physiology and behavior of other model organisms to hypothesize how host–microbe interactions at the individual level could shape societal dynamics and evolution. 

Diffraction-limited radial-velocity instruments offer a pathway towards improved precision and stability, and the exploration of new parameter spaces at high spatial and spectral resolution. However, achieving the necessary performance requires careful instrument design and considerable on-sky testing. We describe the design and construction of ‘Little iLocater’ (Lili), a compact spectrograph that has been used to validate the performance of the front-end fibre-injection system of the iLocater spectrograph. We present the design, assembly, and performance using on-sky data obtained at the Large Binocular Telescope (LBT), including extraction of spectra from standard stars, testing of the atmospheric dispersion corrector to elevations of 40°, and spatially resolved spectra from close companion systems. These results show the front-end fibre-injection system is performing as expected and is indicative of iLocater’s capabilities once installed at the LBT. 

The synthesis of heavy elements in supernovae is affected by low-energy $(n,p)$ and $(p,n)$ reactions on unstable nuclei, yet experimental data on such reaction rates are scarce. The SECAR (SEparator for CApture Reactions) recoil separator at FRIB (Facility for Rare Isotope Beams) was originally designed to measure astrophysical reactions that change the mass of a nucleus significantly. We used a novel approach that integrates machine learning with ion-optical simulations to find an ion-optical solution for the separator that enables the measurement of $(p,n)$ reactions, despite the reaction leaving the mass of the nucleus nearly unchanged. A new measurement of the ${}^{58}\mathrm{Fe}(p,n){}^{58}\mathrm{Co}$ reaction in inverse kinematics with a $3.66\pm 0.12$ MeV/nucleon ${}^{58}\mathrm{Fe}$ beam (corresponding to $3.69\pm 0.12$ MeV proton energy in normal kinematics) yielded a cross-section of $20.3\pm 6.3$  mb and served as a proof of principle experiment for the new technique demonstrating its effectiveness in achieving the required performance criteria. This novel approach paves the way for studying astrophysically important $(p,n)$ reactions on unstable nuclei produced at FRIB. Published by the American Physical Society2025