High Time Resolution Research Articles

Xylem sap residue in cut-open conduits can affect gas discharge in pneumatic experiments.

Considerable attention has been paid to address methodological concerns related to measurements of embolism in conduits of angiosperm xylem. A fast, easy, and cheap method is based on gas extraction measurements from dehydrating samples to obtain pneumatic vulnerability curves (VCs). Here, we tested the assumption that cutting open conduits leads to gas-filled lumina when these are cut in air at fairly high water potentials, which is required to detect embolism in intact conduits. We performed VCs with the Pneumatron for 12 angiosperm species, and extracted sap from cut-open vessels in branches of nine species under early stages of branch dehydration. The optical method was applied to Citrus plants as an alternative reference method to estimate embolism resistance. We found an increase in gas discharge during early stages of dehydration, which affected the pneumatic VCs for most of the species studied. Xylem sap residue was not absorbed immediately by surrounding tissue in cut-open conduits in six of the nine species, but gradually disappeared over time during progressive dehydration. The amount of gas discharged increased until all residual sap was absorbed, and was not related to embolism. We conclude that residual xylem sap in cut-open conduits affects early stages of pneumatic VCs, and represents a novel artefact that can easily be corrected for. Yet, it remains unclear why exactly the air-water meniscus in cut-open conduits did not fully withdraw to the conduit end wall in most species. By analysing the slope of VCs over time, we could improve estimations of embolism resistance, as evidenced by a strong agreement between the pneumatic and the optical methods. Since residual sap in cut-open conduits of some species could slightly underestimate embolism resistance, we propose to apply a correction for this artefact based on the high time resolution measurements taken with a Pneumatron.

Monitoring resilience in bursts

The possibility to anticipate critical transitions through detecting loss of resilience has attracted attention in many fields. Resilience indicators rely on the mathematical concept of critical slowing down, which means that a system recovers more slowly from external perturbations when it gets closer to tipping point. This decrease in recovery rate can be reflected in rising autocorrelation and variance in data. To test whether resilience is changing, resilience indicators are often calculated using a moving window in long, continuous time series of the system. However, for some systems, it may be more feasible to collect several high-resolution time series in short periods of time, i.e., in bursts. Resilience indicators can then be calculated to detect a change of resilience between such bursts. Here, we compare the performance of both methods using simulated data and showcase the possible use of bursts in a case study using mood data to anticipate depression in a patient. With the same number of data points, the burst approach outperformed the moving window method, suggesting that it is possible to downsample the continuous time series and still signal an upcoming transition. We suggest guidelines to design an optimal sampling strategy. Our results imply that using bursts of data instead of continuous time series may improve the capacity to detect changes in resilience. This method is promising for a variety of fields, such as human health, epidemiology, or ecology, where continuous monitoring can be costly or unfeasible.

A dual RNA-seq analyses revealed dynamic arms race during the invasion of walnut by Colletotrichum gloeosporioides

BackgroundWalnut anthracnose caused by Colletotrichum gloeosporioides seriously endangers the yield and quality of walnut, and has now become a catastrophic disease in the walnut industry. Therefore, understanding both pathogen invasion mechanisms and host response processes is crucial to defense against C. gloeosporioides infection.ResultsHere, we investigated the mechanisms of interaction between walnut fruits (anthracnose-resistant F26 fruit bracts and anthracnose-susceptible F423 fruit bracts) and C. gloeosporioides at three infection time points (24hpi, 48hpi, and 72hpi) using a high-resolution time series dual transcriptomic analysis, characterizing the arms race between walnut and C. gloeosporioides. A total of 20,780 and 6670 differentially expressed genes (DEGs) were identified in walnut and C. gloeosporioides against 24hpi, respectively. Generous DEGs in walnut exhibited opposite expression patterns between F26 and F423, which indicated that different resistant materials exhibited different transcriptional responses to C. gloeosporioides during the infection process. KEGG functional enrichment analysis indicated that F26 displayed a broader response to C. gloeosporioides than F423. Meanwhile, the functional analysis of the C. gloeosporioides transcriptome was conducted and found that PHI, SignalP, CAZy, TCDB genes, the Fungal Zn (2)-Cys (6) binuclear cluster domain (PF00172.19) and the Cytochrome P450 (PF00067.23) were largely prominent in F26 fruit. These results suggested that C. gloeosporioides secreted some type of effector proteins in walnut fruit and appeared a different behavior based on the developmental stage of the walnut.ConclusionsOur present results shed light on the arms race process by which C. gloeosporioides attacked host and walnut against pathogen infection, laying the foundation for the green prevention of walnut anthracnose.

Assessing the Impact of Non-Exhaust Emissions on the Asthmatic Airway (IONA) Protocol for a Randomised Three-Exposure Crossover Study.

People living with asthma are disproportionately affected by air pollution, with increased symptoms, medication usage, hospital admissions, and the risk of death. To date, there has been a focus on exhaust emissions, but traffic-related air pollution (TRAP) can also arise from the mechanical abrasion of tyres, brakes, and road surfaces. We therefore created a study with the aim of investigating the acute impacts of non-exhaust emissions (NEEs) on the lung function and airway immune status of asthmatic adults. A randomised three-condition crossover panel design will expose adults with asthma using a 2.5 h intermittent cycling protocol in a random order at three locations in London, selected to provide the greatest contrast in the NEE components within TRAP. Lung function will be monitored using oscillometry, fractional exhaled nitric oxide, and spirometry (the primary outcome is the forced expiratory volume in one second). Biomarkers of inflammation and airborne metal exposure will be measured in the upper airway using nasal lavage. Symptom responses will be monitored using questionnaires. Sources of exhaust and non-exhaust concentrations will be established using source apportionment via the positive matrix factorisation of high-time resolution chemical measures conducted at the exposure sites. Collectively, this study will provide us with valuable information on the health effects of NEE components within ambient PM2.5 and PM10, whilst establishing a biological mechanism to help contextualise current epidemiological observations.

Following the Structural Changes of Iron Oxides during Reduction under Transient Conditions.

Iron is considered as attractive energy carrier in a carbon-free circular energy economy. The reduction of iron oxide is crucial for its applica-tion as a metal fuel as it determines the efficiency of the cycle. Temperature programmed reduction of α-Fe2O3 was monitored by complementary X-ray absorption spectroscopy (XAS) and diffraction (XRD) to obtain the phase composition with high time resolution. Synchrotron Mössbauer spectroscopy (SMS) was additionally employed due to its high sensitivity to the different iron species. Theoretical calculations of surface and bulk adsorption processes were performed to establish the potential reaction pathways and the corresponding energy barriers. A kinetic particle model was then developed to bridge the experimental data and theoretical calculations, which reproduced the reduction onset and behavior. The reduction process was found to be strongly dependent on the heating rate in terms of the reduction window and the observed intermediate species. We propose that a core-shell mechanism determines the reaction by forming an iron layer which subsequently hinders diffusion of water out of the porous particles leading to some unreduced FeO at high temperature. This study demonstrates the need for complementary methods for describing complex heterogeneous systems and overcoming the chemical sensitivity limitations of any single method.

Underwater Single-Photon 3D Reconstruction Algorithm Based on K-Nearest Neighbor.

The high sensitivity and picosecond time resolution of single-photon avalanche diodes (SPADs) can improve the operational range and imaging accuracy of underwater detection systems. When an underwater SPAD imaging system is used to detect targets, backward-scattering caused by particles in water often results in the poor quality of the reconstructed underwater image. Although methods such as simple pixel accumulation have been proven to be effective for time-photon histogram reconstruction, they perform unsatisfactorily in a highly scattering environment. Therefore, new reconstruction methods are necessary for underwater SPAD detection to obtain high-resolution images. In this paper, we propose an algorithm that reconstructs high-resolution depth profiles of underwater targets from a time-photon histogram by employing the K-nearest neighbor (KNN) to classify multiple targets and the background. The results contribute to the performance of pixel accumulation and depth estimation algorithms such as pixel cross-correlation and ManiPoP. We use public experimental data sets and underwater simulation data to verify the effectiveness of the proposed algorithm. The results of our algorithm show that the root mean square errors (RMSEs) of land targets and simulated underwater targets are reduced by 57.12% and 23.45%, respectively, achieving high-resolution single-photon depth profile reconstruction.

Joint extraction-based multivariate chirp mode decomposition and its application to fault diagnosis of rotating machinery under variable speed conditions

Vibration signals from rotating machinery during variable speed conditions exhibits non-stationary characteristics, posing a challenge for fault diagnosis. When a machine fails, the vibration signal of any component connected to the bearing carries valuable information about the equipment’s status. Processing multichannel variable speed signals at the same time avoids losing part of information and improves fault diagnosis. Therefore, this study put up a novel approach called joint extraction-based multivariate chirp mode decomposition (JMCMD) to analyze multichannel signals of rotating machinery with varying speeds. The approach comprises the joint extraction framework and the multichannel signal instantaneous frequency initialization (MSIFI). First, JMCMD employs a joint component extraction framework, which can precisely and simultaneously extract complicated characteristic components close to each other in multiple channels. Second, this study extends the parameterized demodulation (PD) technique to multiple channels to find the initialized instantaneous frequency of multichannel signals. Through the joint extraction strategy’s integration with MSIFI, JMCMD is capable of efficaciously extracting all significant characteristic components of multichannel signals. Additionally, the high-resolution time–frequency representation (TFR) constructed from JMCMD’s output can clearly reveal the time-varying fault characteristic frequency of the rotor-bearing system. Simulation analysis and actual cases demonstrate that the suggested approach is an effective way to identify fault feature components, making it highly applicable in signal decomposition and fault detection.

Recent Advances in Fast-Decaying Metal Halide Perovskites Scintillators.

Fast-decaying scintillators show subnanoseconds or nanoseconds lifetime and high time resolution, making them important in nuclear physics, medical diagnostics, scientific research, and other fields. Metal halide perovskites (MHPs) show great potential for scintillator applications owing to their easy synthesis procedure and attractive optical properties. However, MHPs scintillators still need further improvement in decay lifetime. To optimize the decay lifetime, great progress has been achieved recently. In this Perspective, we first summarize the structural characteristics of MHPs in various dimensions, which brings different exciton behaviors. Then, recent advances in designing fast-decaying MHPs according to different exciton behaviors have been concluded, focusing on the photophysical mechanisms to achieve fast-decaying lifetimes. These advancements in decay lifetimes could facilitate the MHPs scintillators in advanced applications, such as time-of-flight positron emission tomography (TOF-PET), photon-counting computed tomography (PCCT), etc. Finally, the challenges and future opportunities are discussed to provide a roadmap for designing novel fast-decaying MHPs scintillators.

Characterization of the BOLDPET optical prototype, an innovative Cherenkov detector for 511 keV γ radiation

In the present work we describe the design, construction, and testing of the optical prototype developed for the BOLDPET project, with the objective of creating a PET detection module with high spatial and time resolution. The BOLDPET technology uses an innovative detection liquid, trimethylbismuth, for detecting 511 keV γ-quanta resulting from positron annihilation. The optical signal is exclusively produced through the Cherenkov mechanism, and the produced photons are detected using Planacon microchannel-plate photomultiplier. We achieve an excellent time resolution of 150 ps (FWHM) within a sizable detection volume measuring 55 mm× 55 mm× 25 mm. Through detailed Geant4 simulations, we examine the limiting factors affecting time resolution and explore potential avenues for improvement. Furthermore, we demonstrate the feasibility of coarse 2D localization of interactions using the optical signal alone, achieving a precision of about 5–8 mm (FWHM) within the homogeneous detection volume.

Figuring Out Gas and Galaxies in Enzo (FOGGIE). VII. The (Dis)assembly of Stellar Halos

Over the next decade, the astronomical community will be commissioning multiple wide-field observatories well suited for studying stellar halos in both integrated light and resolved stars. In preparation for this, we use five high-resolution cosmological simulations of Milky Way–like galaxies from the FOGGIE suite to explore the properties and components of stellar halos. These simulations are run with high time (5 Myr) and stellar mass (1000 M ⊙) resolution to better model the properties and origins of low-density regions like stellar halos. We find that the FOGGIE stellar halos have masses, metallicity gradients, and surface brightness profiles that are consistent with observations. In agreement with other simulations, the FOGGIE stellar halos receive 30%–40% of their mass from in situ stars. However, this population is more centrally concentrated in the FOGGIE simulations and therefore does not contribute excess light to the halo outskirts. The remaining stars are accreted from ∼10–50 other galaxies, with the majority of the accreted mass originating in two to four galaxies. While the inner halo (r < 50 kpc) of each FOGGIE galaxy has a large number of contributors, the halo outskirts of three of the five galaxies are primarily made up of stars from only a few contributors. We predict that upcoming wide-field observatories, like the Nancy Grace Roman Space Telescope, will probe stellar halos around Milky Way–like galaxies out to ∼100 kpc in integrated light and will be able to distinguish the debris of dwarf galaxies with extended star formation histories from the underlying halo with resolved color–magnitude diagrams.

Acceptance Tests of more than 10 000 Photomultiplier Tubes for the multi-PMT Digital Optical Modules of the IceCube Upgrade

More than 10000 photomultiplier tubes (PMTs) with a diameter of 80 mm will be installed in multi-PMT Digital Optical Modules (mDOMs) of the IceCube Upgrade. These have been tested and pre-calibrated at two sites. A throughput of more than 1000 PMTs per week with both sites was achieved with a modular design of the testing facilities and highly automated testing procedures. The testing facilities can easily be adapted to other PMTs, such that they can, e.g., be re-used for testing the PMTs for IceCube-Gen2. Single photoelectron response, high voltage dependence, time resolution, prepulse, late pulse, afterpulse probabilities, and dark rates were measured for each PMT. We describe the design of the testing facilities, the testing procedures, and the results of the acceptance tests.

The Curious Case of Twin Fast Radio Bursts: Evidence for Neutron Star Origin?

Fast radio bursts (FRBs) are brilliant short-duration flashes of radio emission originating at cosmological distances. The vast diversity in the properties of currently known FRBs and the fleeting nature of these events make it difficult to understand their progenitors and emission mechanism(s). Here we report high time resolution polarization properties of FRB 20210912A, a highly energetic event detected by the Australian Square Kilometre Array Pathfinder (ASKAP) in the Commensal Real-time ASKAP Fast Transients survey, which show intraburst position angle (PA) variation similar to Galactic pulsars and unusual variation of Faraday rotation measure (RM) across its two sub-bursts. The observed intraburst PA variation and apparent RM variation pattern in FRB 20210912A may be explained by a rapidly spinning neutron star origin, with rest-frame spin periods of ∼1.1 ms. This rotation timescale is comparable to the shortest known rotation period of a pulsar and close to the shortest possible rotation period of a neutron star. Curiously, FRB 20210912A exhibits a remarkable resemblance to the previously reported FRB 20181112A, including similar rest-frame emission timescales and polarization profiles. These observations suggest that these two FRBs may have similar origins.

The solar cycle 25 multi-spacecraft solar energetic particle event catalog of the SERPENTINE project

Context. The solar energetic particle analysis platform for the inner heliosphere (SERPENTINE) project, funded through the H2020-SPACE-2020 call of the European Union’s Horizon 2020 framework program, employs measurements of the new inner heliospheric spacecraft fleet to address several outstanding questions on the origin of solar energetic particle (SEP) events. The data products of SERPENTINE include event catalogs, which are provided to the scientific community. Aims. In this paper, we present SERPENTINE’s new multi-spacecraft SEP event catalog for events observed in solar cycle 25. Observations from five different viewpoints are utilized, provided by Solar Orbiter, Parker Solar Probe, STEREO A, BepiColombo, and the near-Earth spacecraft Wind and SOHO. The catalog contains key SEP parameters for 25–40 MeV protons, ~1 MeV electrons, and ~100 keV electrons. Furthermore, basic parameters of associated flares and type II radio bursts are listed, as are the coordinates of the observer and solar source locations. Methods. An event is included in the catalog if at least two spacecraft detect a significant proton event with energies of 25–40 MeV. The SEP onset times were determined using the Poisson-CUSUM method. The SEP peak times and intensities refer to the global intensity maximum. If different viewing directions are available, we used the one with the earliest onset for the onset determination and the one with the highest peak intensity for the peak identification. We furthermore aimed to use a high time resolution to provide the most accurate event times. Therefore, we opted to use a 1-min time resolution, and more time averaging of the SEP intensity data was only applied if necessary to determine clean event onsets and peaks. Associated flares were identified using observations from near Earth and Solar Orbiter. Associated type II radio bursts were determined from ground-based observations in the metric frequency range and from spacecraft observations in the decametric range. Results. The current version of the catalog contains 45 multi-spacecraft events observed in the period from November 2020 until May 2023, of which 13 events were found to be widespread (observed at longitudes separated by at least 80° from the associated flare location) and four could be classified as narrow-spread events (not observed at longitudes separated by at least 80° from the associated flare location). Using X-ray observations by GOES/XRS and Solar Orbiter/STIX, we were able to identify the associated flare in all but four events. Using ground-based and space-borne radio observations, we found an associated type II radio burst for 40 events. In total, the catalog contains 142 single event observations, of which 20 (45) have been observed at radial distances below 0.6 AU (0.8 AU). It is anticipated that the catalog will be extended in the future.

Characterizing Supply Reliability Through the Synergistic Integration of VRE towards Enhancing Electrification in Kenya

Decentralized electrical power systems, driven by variable renewable energy sources such as solar PV and wind, have the potential to provide accessible and sustainable energy, contributing to the realization of a zero-carbon transition. However, these sources are susceptible to extreme weather conditions, presenting a challenge to the reliability of the power system. With abundant resources and a significant rural population lacking access to electricity, Africa has emerged as a key area for research on variable renewable energy-based electricity generation. Despite this focus, there remains a substantial gap in understanding at regional-scale the potential and variability of solar and wind power across various time scales, as well asthe impact of available resource synergy. Thisstudy aims to bridge this knowledge gap by conducting comprehensive simulations of hybrid wind and solar energy systems, both on-grid and off-grid, across 20 geographically diverse locations in Kenya. Using high-resolution hourly time step data, we examine the effect of resource complementarity on system reliability at varying time scales: daily, monthly and annually. The study findings shows the available VRE resource exhibit moderate tendency for complementarity, and optimizing their deployment can reduce hourly variability by 20%, significantly enhancing supply reliability, especially in the northern and eastern regions.

Core inductive electric field during sawtooth crashes on DIII-D

Sawtooth crashes on tokamak plasmas exhibit relaxation much faster than resistive time scales via a mechanism not fully understood. Using core magnetic measurements from the Radial Interferometer-Polarimeter (RIP) diagnostic on the DIII-D tokamak, Grad–Shafranov equilibria constrained by internal magnetic measurements that have high time resolution ( <1 µs) can be computed, allowing analysis of how equilibrium parameters such as safety factor q, current density J, and parallel electric field E∥ , particularly on-axis, evolve. At the sawtooth crash, on-axis safety factor q 0 is observed to rise by 5% but remain below 1 throughout the cycle, and on-axis current density J 0 is observed to drop by 5%. On-axis parallel electric field E∥(0) is found to be balanced by ηJ0 (resistivity times on-axis current density) except during the 200 µs crash period, where E∥(0) reaches 22 V m−1, exceeding ηJ0 by a factor of more than 2000. These first measurements in tokamak plasmas verify that generalized Ohm’s law is not balanced during the crash by resistive effects alone; this is a finding expected due to the relaxation being much faster than resistive timescales. Measurement of the electric field during the tokamak sawtooth serves to illuminate the physical mechanisms at work.

Optical dating of charcoal kiln remains from WWII: A test of accuracy

The majority of relic charcoal kilns in Europe are more recent than 1650 CE and cannot be precisely dated using radiocarbon dating (14C). Quartz-based optically stimulated luminescence (OSL) dating of the sediments associated with the kiln remains has been suggested as a viable alternative. Owing to the lack of reliable and sufficiently precise independent age information, however, it remains to be established whether OSL dating can yield accurate ages for post-1650 CE features. This is explicitly investigated in this study by applying a commonly adopted quartz OSL methodology to three relic charcoal kilns which are known to have been constructed and operated between December 1941 and March/April 1942 CE.We first document the quartz luminescence characteristics and show through procedural tests that the adopted single-aliquot regenerative dose procedure should be appropriate for equivalent dose determination. Four samples collected from the uppermost part of the charcoal-rich layers in the three features yield the youngest optical ages and are considered coeval. Their average age is 1928 ± 13 CE (95% probability), which matches the independent age reasonably well. The precision associated with the individual OSL ages ranges between 7 and 14% (1 sigma total uncertainty) and it might ideally be possible to establish relative chronologies with a higher time resolution. Finally, we briefly discuss our entire set of OSL ages in relation to future strategies for sampling charcoal kilns remains. In general, we conclude that OSL dating can be particularly advantageous to help resolving chronometric issues that pertain to post-1650 CE relic charcoal kilns.

Orbital-paced Oceanic Anoxic Event 2 evolution and astrochronology in the Mentelle Basin (Australia) at southern high latitudes

The Oceanic Anoxic Event 2 (OAE 2) is widely regarded as one of the most significant global-scale biological and environmental perturbations in the Mesozoic Era. However, the duration and driving mechanisms of this event at southern high latitudes remain largely unknown due to a lack of available geological records. Here, we present a cyclostratigraphic analysis of high-resolution records of lightness variability (L*) and gamma-ray attenuation (GRA) bulk density, which are associated with changes of marine primary productivity and continental weathering, respectively, from Site U1516 located in the Mentelle Basin, offshore southwest Australia. This analysis permits establishment of an astronomical time framework for a stratigraphic interval of 455.205–485.24 m rCCSF (revised Core Composite Depth below Sea Floor) by tuning the 100 kyr filter to short eccentricity. The studied section encompasses the entire OAE 2 interval at the depth of 460.13–473.94 m rCCSF. Based on the established high-resolution astronomical time scale using astronomical tuning of L* records to the short eccentricity cycles (100 kyr), the duration of OAE 2 is estimated to be ∼990 kyr at Site U1516. A relatively high amplitude of short eccentricity occurred at the build-up stage, accompanied by a gradual rise in obliquity amplitude during the recovery phase of the OAE 2. Combining previous proposals for enhanced oceanic water stratification and terrestrial weathering, we suggest that obliquity, coupled with short eccentricity, paced the evolution of this event at southern high latitudes by controlling insolation changes received by the Earth's surface.

EEG-based TSK fuzzy graph neural network for driver drowsiness estimation

With the development of brain-computer interface (BCI), electroencephalogram (EEG) is considered to be one of the best physiological signals to detect the fatigue state of drivers due to its advantages of extremely high time resolution and low use cost. However, since EEG is sensitive to noise/artifacts, and there is non-stationarity and low signal-to-noise ratio in inter-subject/intra-subject, the accurate estimation of driver drowsiness state remains challenging. Therefore, this paper proposes the EEG-based TSK fuzzy graph neural network (TSKG) to solve the regression problem of driver drowsiness estimation by combining transfer learning (TL), graph convolutional neural network (GCN), information theory, and TSK fuzzy neural network. TSKG extracts the relevant features in EEG through mutual information minimization and regards the fuzzy rules as graph structure data. The extracted relevant features and the original features are used to optimize the fuzzy rules through GCN. TSKG is tested on the fatigue driving dataset, and Root Mean Square Error (RMSE) and Correlation Coefficient (CC) are 0.1681 and 0.7118, respectively. Especially when dealing with difficult samples, TSKG has significantly better generalization performance.

Warming effect of the desert regulates spatio-temporal distribution of cotton Verticillium wilt for the oasis agriculture ecosystem

Verticillium wilt (VW) is threatening global cotton yield and quality. However, the accurate spatio-temporal dynamics of cotton VW in large regions remain unclear, especially in the complicated oasis agriculture ecosystem. We explored the spatio-temporal distribution of VW in the cotton-dominated region of Northern Xinjiang characterized by a typical desert-oasis irrigation agriculture ecosystem, utilizing reconstructed high-resolution time series remote sensing data from 2019 to 2021. Results revealed that the area of VW-infected cotton remained consistently around 20 % each year. However, there were significant seasonal variations, with outbreaks peaking in August. Regarding the spatial pattern of cotton VW, the mean temperature (TMP) difference in irrigated cotton fields along the Gurbantunggut Desert-oasis gradient reaches a maximum of approximately 1 ℃ caused by warming effect of the desert on the oasis (WEDO) during the cotton growing period. This TMP difference drives the spatial pattern of cotton VW incidence characterized by a low-to-high-to-moderate trend. WEDO significantly suppresses the cotton VW incidence due to relatively higher TMP, forming the low-risk zone for cotton VW within 16 km near the Gurbantunggut Desert. Our study significantly enhances the understanding of the spatio-temporal dynamics of cotton VW in the distinctive oasis irrigation agricultural ecosystem and advances the accurate monitoring and assessment of cotton VW across large regions.

HD 110067 c has an aligned orbit

Planetary systems in mean motion resonances hold a special place among the planetary population. They allow us to study planet formation in great detail as dissipative processes are thought to have played an important role in their existence. Additionally, planetary masses in bright resonant systems can be independently measured via both radial velocities and transit timing variations. In principle, they also allow us to quickly determine the inclination of all planets in the system since, for the system to be stable, they are likely all in coplanar orbits. To describe the full dynamical state of the system, we also need the stellar obliquity, which provides the orbital alignment of a planet with respect to the spin of its host star and can be measured thanks to the Rossiter–McLaughlin effect. It was recently discovered that HD 110067 harbors a system of six sub-Neptunes in resonant chain orbits. We here analyze an ESPRESSO high-resolution spectroscopic time series of HD 110067 during the transit of planet c. We find the orbit of HD 110067 c to be well aligned, with a sky-projected obliquity of λ =6+24-26 deg. This result indicates that the current architecture of the system was reached through convergent migration without any major disruptive events. Finally, we report transit-timing variation in this system as we find a significant offset of 19 ± 4 min in the center of the transit compared to the published ephemeris.