Comparisons of the alignment of exoplanets with a common host star and each other can be used to distinguish among concurrent evolution scenarios for the star and the planets. However, multi-planet ...systems usually host mini-Neptunes and super-Earths, whose sizes make orbital architecture measurements challenging. We introduce the Rossiter-McLaughlin effect Revolutions (RMR) technique, which can access the spin-orbit angle of small exoplanets by exploiting the full extent of information contained in spectral transit time series. We validated the technique through its application to published HARPS-N data of the mini-Neptune HD 3167c (
P
= 29.8 days), refining its high sky-projected spin-orbit angle (−108.9
−5.5
+5.4°
), and we applied it to new ESPRESSO observations of the super-Earth HD 3167 b (
P
= 0.96 days), revealing an aligned orbit (−6.6
−7.9
+6.6°
). Surprisingly different variations in the contrast of the stellar lines occulted by the two planets can be reconciled by assuming a latitudinal dependence of the stellar line shape. In this scenario, a joint fit to both datasets constrains the inclination of the star (111.6
−3.3
+3.1°
) and the 3D spin-orbit angles of HD 3167b (29.5
−9.4
+7.2°
) and HD 3167c (107.7
−4.9
+5.1°
). The projected spin-orbit angles do not depend on the model for the line contrast variations, and so, with a mutual inclination of 102.3
−8.0
+7.4°
, we can conclude that the two planets are on perpendicular orbits. This could be explained by HD 3167b being strongly coupled to the star and retaining its primordial alignment, whereas HD 3167c would have been brought to a nearly polar orbit via secular gravitational interactions with an outer companion. Follow-up observations of the system and simulations of its dynamical evolution are required to search for this companion and explore the likelihood of this scenario. HD 3167 b (
R
= 1.7
R
Earth
) is the smallest exoplanet with a confirmed spectroscopic Rossiter-McLaughlin signal. The RMR technique opens the way to determining the orbital architectures of the super-Earth and Earth-sized planet populations.
Distributed maximum power point tracking (DMPPT) is a topic of much interest in improving photovoltaic (PV) system performance. This study uses measured performance data at the module level for 542 ...PV systems to estimate lost system performance due to partial shade. Because each of the monitored systems is equipped with module-level dc power optimizers, an estimate is made of the overall system shading loss and the performance improvement that the system has received from this use of DMPPT. The estimate of shade extent and performance improvement predicted by this approach is verified experimentally against a system that has site survey images, and measured production with and without module-level electronics. Summary data for this analysis across 542 systems find an average power loss of 8.3% due to partial shading, which would have increased to 13% were the systems not equipped with panel-level optimizers. It is estimated that on average, 36% of the power lost from partial shading has been recovered through use of module-level dc power electronics.
Context . Long-period transiting exoplanets bridge the gap between the bulk of transit- and Doppler-based exoplanet discoveries, providing key insights into the formation and evolution of planetary ...systems. The wider separation between these planets and their host stars results in the exoplanets typically experiencing less radiation from their host stars; hence, they should maintain more of their original atmospheres, which can be probed during transit via transmission spectroscopy. Although the known population of long-period transiting exoplanets is relatively sparse, surveys performed by the Transiting Exoplanet Survey Satellite (TESS) and the Next Generation Transit Survey (NGTS) are now discovering new exoplanets to fill in this crucial region of the exoplanetary parameter space. Aims . This study aims to characterise a new long-period transiting exoplanet by following up on a single-transit candidate found in the TESS mission. Methods . The TOI-4862 system was monitored using a combination of photometric instruments (TESS, NGTS, and EulerCam) and spectroscopic instruments (CORALIE, FEROS, HARPS, and PFS) in order to determine the period, radius, and mass of the long-period transiting exoplanet NGTS-30 b/TOI-4862 b. These observations were then fitted simultaneously to determine precise values for the properties and orbital parameters of the exoplanet, as well as the refined stellar parameters of the host star. Results . We present the discovery of a long-period ( P = 98.29838 ± 0.00010 day) Jupiter-sized (0.928 ± 0.032 R J ; 0.960 ± 0.056 M J ) planet transiting a 1.1 Gyr old G-type star, one of the youngest warm Jupiters discovered to date. NGTS-30 b/TOI-4862 b has a moderate eccentricity (0.294 −0.010 +0.014 ), meaning that its equilibrium temperature can be expected to vary from 274 −46 +30 K to 500 −84 +55 K over the course of its orbit. Through interior modelling, NGTS-30 b/TOI-4862b was found to have a heavy element mass fraction of 0.23 −0.06 +0.05 and a heavy element enrichment ( Z p / Z ★ ) of 20 −6 +5 , making it metal-enriched compared to its host star. Conclusions . NGTS-30 b/TOI-4862 b is one of the youngest well-characterised long-period exoplanets found to date and will therefore be important in the quest to understanding the formation and evolution of exoplanets across the full range of orbital separations and ages.
High-resolution optical spectroscopy is a powerful tool to characterise exoplanetary atmospheres from the ground. The sodium D lines, with their large cross sections, are especially suited to ...studying the upper layers of atmospheres in this context. We report on the results from Hot Exoplanet Atmosphere Resolved with Transit Spectroscopy survey (HEARTS), a spectroscopic survey of exoplanet atmospheres, performing a comparative study of hot gas giants to determine the effects of stellar irradiation. In this second installation of the series, we highlight the detection of neutral sodium on the ultra-hot giant WASP-76b. We observed three transits of the planet using the High-Accuracy Radial-velocity Planet Searcher (HARPS) high-resolution spectrograph at the European Southern Observatory (ESO) 3.6 m telescope and collected 175 spectra of WASP-76. We repeatedly detect the absorption signature of neutral sodium in the planet atmosphere (0.371 ± 0.034%; 10.75
σ
in a 0.75 Å passband). The sodium lines have a Gaussian profile with full width at half maximum (FWHM) of 27.6 ± 2.8 km s
−1
. This is significantly broader than the line spread function of HARPS (2.7 km s
−1
). We surmise that the observed broadening could trace the super-rotation in the upper atmosphere of this ultra-hot gas giant.
Context
. The characterisation of Earth-size exoplanets through transit photometry has stimulated new generations of high-precision instruments. In that respect, the Characterising Exoplanet ...Satellite (CHEOPS) is designed to perform photometric observations of bright stars to obtain precise radii measurements of transiting planets. The CHEOPS instrument will have the capability to follow up bright hosts provided by radial-velocity facilities. With the recent launch of the Transiting Exoplanet Survey Satellite (TESS), CHEOPS may also be able to confirm some of the long-period TESS candidates and to improve the radii precision of confirmed exoplanets.
Aims
. The high-precision photometry of CHEOPS relies on careful on-ground calibration of its payload. For that purpose, intensive pre-launch campaigns of measurements were carried out to calibrate the instrument and characterise its photometric performances. This work reports on the main results of these campaigns. It provides a complete analysis of data sets and estimates in-flight photometric performance by means of an end-to-end simulation. Instrumental systematics were measured by carrying out long-term calibration sequences. Using an end-to end model, we simulated transit observations to evaluate the impact of in-orbit behaviour of the satellite and to determine the achievable precision on the planetary radii measurement.
Methods
. After introducing key results from the payload calibration, we focussed on the data analysis of a series of long-term measurements of uniformly illuminated images. The recorded frames were corrected for instrumental effects and a mean photometric signal was computed on each image. The resulting light curve was corrected for systematics related to laboratory temperature fluctuations. Transit observations were simulated, considering the payload performance parameters. The data were corrected using calibration results and estimates of the background level and position of the stellar image. The light curve was extracted using aperture photometry and analysed with a transit model using a Markov chain Monte Carlo algorithm.
Results
. In our analysis, we show that the calibration test set-up induces thermally correlated features in the data that can be corrected in post-processing to improve the quality of the light curves. We find that on-ground photometric performances of the instrument measured after this correction is of the order of 15 parts per million over five hours. Using our end-to-end simulation, we determine that measurements of planet-to-star radii ratio with a precision of 2% for a Neptune-size planet transiting a K-dwarf star and 5% for an Earth-size planet orbiting a Sun-like star are possible with CHEOPS. These values correspond to transit depths obtained with signal-to-noise ratios of 25 and 10, respectively, allowing the characterisation and detection of these planets. The pre-launch CHEOPS performances are shown to be compliant with the mission requirements.
Transmission spectroscopy is a proven technique for studying a transiting exoplanet’s atmosphere. However, stellar surface inhomogeneities – spots and faculae – alter the observed transmission ...spectra: the stellar contamination effect. The variable nature of the stellar activity also makes it difficult to stitch together multi-epoch observations and evaluate any potential variability in the exoplanet’s atmosphere. This paper introduces SAGE , a tool that corrects for the time-dependent impact of stellar activity on transmission spectra. It uses a pixelation approach to model the stellar surface with spots and faculae, while fully accounting for limb-darkening and rotational line-broadening. The current version is designed for low- to medium-resolution spectra. We used SAGE to evaluate stellar contamination for F- to M-type hosts, testing various spot sizes and locations, and quantify the impact of limb-darkening. We find that limb-darkening enhances the importance of the spot location on the stellar disc, with spots close to the disc centre impacting the transmission spectra more strongly than spots near the limb. Moreover, due to the chromaticity of limb-darkening, the shape of the contamination spectrum is also altered. Additionally, SAGE can be used to retrieve the properties and distribution of active regions on the stellar surface from photometric monitoring. We demonstrate this for WASP-69 using TESS data, finding that two spots at midlatitudes and a combined coverage fraction of ~1% are favoured. SAGE allows us to connect the photometric variability to the stellar contamination of transmission spectra, enhancing our ability to jointly interpret transmission spectra obtained at different epochs.
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