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In this work, we derive systemic velocities for 8456 RR Lyrae stars. This is the largest dataset of these variables in the Galactic bulge to date. In combination withGaiaproper motions, we computed their orbits using an analytical gravitational potential similar to that of the Milky Way (MW) and identified interlopers from other MW structures, which amount to 22% of the total sample. Our analysis revealed that most interlopers are associated with the halo, and the remainder are linked to the Galactic disk. We confirm the previously reported lag in the rotation curve of bulge RR Lyrae stars, regardless of the removal of interlopers. The rotation patterns of metal-rich RR Lyrae stars are consistent with the pattern of nonvariable metal-rich giants, following the MW bar, while metal-poor stars rotate more slowly. The analysis of the orbital parameter space was used to distinguish bulge stars that in the bar reference frame have prograde orbits from those on retrograde orbits. We classified the prograde stars into orbital families and estimated the chaoticity (in the form of the frequency drift, log ΔΩ) of their orbits. RR Lyrae stars with banana-like orbits have a bimodal distance distribution, similar to the distance distribution seen in metal-rich red clump stars. The fraction of stars with banana-like orbits decreases linearly with metallicity, as does the fraction of stars on prograde orbits (in the bar reference frame). The retrograde-moving stars (in the bar reference frame) form a centrally concentrated nearly spherical distribution. From analyzing anN-body+SPH simulation, we found that some stellar particles in the central parts oscillate between retrograde and prograde orbits and that only a minority stays prograde over a long period of time. Based on the simulation, the ratio of prograde and retrograde stellar particles seems to stabilize within some gigayears after the bar formation. The nonchaoticity of retrograde orbits and their high numbers can explain some of the spatial and kinematical features of the MW bulge that have been often associated with a classical bulge. 

Permafrost holds more than twice the amount of carbon currently in the atmosphere, but this large carbon reservoir is vulnerable to thaw and erosion under a rapidly changing Arctic climate. Convective storms are becoming increasingly common during Arctic summers and can amplify runoff and erosion. These extreme events, in concert with active layer deepening, may accelerate carbon loss from the Arctic landscape. However, we lack measurements of carbon fluxes during these events. Rivers are sensitive to physical, chemical, and hydrological perturbations, and thus are excellent systems for studying landscape responses to thunderstorms. We present observations from the Canning River, Alaska, which drains the northern Brooks Range and flows across a continuous permafrost landscape to the Beaufort Sea. During summer 2022 and 2023 field campaigns, we opportunistically monitored river discharge, sediment, and organic carbon fluxes during several thunderstorms. During one notable storm, river discharge nearly doubled from ~130 m3/s to ~240 m3/s, suspended sediment flux increased 70-fold, and the particulate organic carbon (POC) flux increased 90-fold relative to non-storm conditions. Taken together, the river exported ~16 metric tons of POC over one hour of this sustained event, not including the additional flux of woody debris. Furthermore, the dissolved organic carbon (DOC) flux nearly doubled. Although these thunderstorm-driven fluxes are short-lived (hours to days), they play an outsized role in exporting organic carbon from Arctic rivers. Understanding how these extreme events impact river water, sediment, and carbon dynamics will help predict how Arctic climate change will modify the global carbon cycle. 

The contribution of river corridors to the global carbon budget exceeds their small areal footprint, yet our understanding of fluvial carbon dynamics is incomplete, particularly in periglacial settings. Frequent disturbance and lateral fluxes are key attributes of carbon budgets in riparian corridors. Climate change affects the pace and style of fluvial and biogeochemical processes in periglacial settings. The effects of these can be assessed with a carbon budget, a statement of all fluxes in and out of a control volume, which we outline for a river corridor. We are generating data from a field campaign of the carbon stock in select river corridor segments of the Canning River, Alaska. This gravel-bedded river drains continuous permafrost from glaciated headwaters in the Brooks Range to its delta in the Beaufort Sea. Fluvial erosion and deposition generate distinct, mappable geomorphic surfaces in the river corridor that accumulate carbon over time. Carbon stocks on surfaces are summed across the river corridor to compute the total carbon stock. Characterizing the depth of alluvium is a poorly constrained component of the carbon stock. Lateral bank erosion hews away geomorphic surfaces, while sediment deposition buries carbon and generates new surfaces. Deposition of uprooted willows or turf mats augment the carbon stock and can jump-start plant succession. All fluxes in the carbon budget are sensitive to warming and arctic hydrologic intensification. Analyzing how these fluxes may change and affect the carbon stock in icy river corridors will advance our understanding of their contribution to the global carbon budget. 

Forest structure plays an important role in determining habitat suitability for plants and animals, but these relationships are poorly characterized for different biological communities in tropical forests. We used ground-based lidar to quantify structural metrics and determine their contribution in predicting species diversity and compositional changes between plots for nine biological groups in an Amazonian forest. For each group, we calculated Fisher’s alpha index and summarized community composition using Principal Coordinates Analysis. As biological organisms may also react directly to hydro-edaphic conditions, we carried out variance partitioning analysis using linear regressions to disentangle the relative contribution of structural metrics and hydro-edaphic variables. Forest structure was related to species diversity and composition of some groups, specifically for plants, anurans, and birds. Mean canopy height, leaf area height volume, and skewness explained more than one-third of species diversity of palms and trees, with higher values relating to higher species diversity. Hydro-edaphic variables were the most important predictors of the main compositional axis for plant groups, but some structural metrics explained more than 30% of the secondary compositional axis for ferns + lycophytes, trees, birds, and anurans. Vegetation height and variability, vegetation quantity, and vertical structure, but not canopy openness, were the main structural characteristics modulating species diversity and composition. Our findings reinforce the potential to estimate species diversity and compositional changes across structural gradients using lidar-derived metrics in a hyper-diverse forest. Understanding these relationships advances our ability to make community predictions useful for conservation and provides new avenues to investigate the mechanisms impacting diversity. 

RR Lyrae stars toward the Galactic bulge are used to investigate whether this old stellar population traces the Galactic bar. Although the bar is known to dominate the mass in the inner Galaxy, there is no consensus on whether the RR Lyrae star population, which constitutes some of the most ancient stars in the bulge and thus traces the earliest epochs of star formation, contributes to the barred bulge. We create new reddening maps and derive new extinction laws from visual to near-infrared passbands using improved RR Lyrae period-absolute magnitude-metallicity relations, enabling distance estimates for individual bulge RR Lyrae variables. The extinction law is most uniform inR_IKsandR_JKsand the distances to individual RR Lyrae based on these colors are determined with an accuracy of 6 and 4%, respectively. Using only the near-infrared passbands for distance estimation, we infer the distance to the Galactic center equal tod^cen_JKs= 8217 ± 1(stat) ± 528(sys) pc after geometrical correction. We show that variations in the extinction law toward the Galactic bulge can mimic a barred spatial distribution in the bulge RR Lyrae star population in visual passbands. This arises from a gradient in extinction differences along Galactic longitudes and latitudes, which can create the perception of the Galactic bar, particularly when using visual passband-based distances. A barred angle in the RR Lyrae spatial distribution disappears when near-infrared passband-based distances are used, as well as when reddening law variations are incorporated in visual passband-based distances. The prominence of the bar, traced by RR Lyrae stars, depends on their metallicity, with metal-poor RR Lyrae stars ([Fe/H] < −1.0 dex) showing little to no tilt with respect to the bar. Metal-rich ([Fe/H] > −1.0 dex) RR Lyrae stars do show a barred bulge signature in spatial properties derived using near-infrared distances, with an angle ofι= 18 ± 5 deg, consistent with previous bar measurements from the literature. This also hints at a younger age for this RR Lyrae subgroup. The 5D kinematic analysis, primarily based on transverse velocities, indicates a rotational lag in RR Lyrae stars compared to red clump giants. Despite variations in the extinction law, our kinematic conclusions are robust across different distance estimation methods. 

Listening to speech in noise can require substantial mental effort, even among younger normal-hearing adults. The task-evoked pupil response (TEPR) has been shown to track the increased effort exerted to recognize words or sentences in increasing noise. However, few studies have examined the trajectory of listening effort across longer, more natural, stretches of speech, or the extent to which expectations about upcoming listening difficulty modulate the TEPR. Seventeen younger normal-hearing adults listened to 60-s-long audiobook passages, repeated three times in a row, at two different signal-to-noise ratios (SNRs) while pupil size was recorded. There was a significant interaction between SNR, repetition, and baseline pupil size on sustained listening effort. At lower baseline pupil sizes, potentially reflecting lower attention mobilization, TEPRs were more sustained in the harder SNR condition, particularly when attention mobilization remained low by the third presentation. At intermediate baseline pupil sizes, differences between conditions were largely absent, suggesting these listeners had optimally mobilized their attention for both SNRs. Lastly, at higher baseline pupil sizes, potentially reflecting over-mobilization of attention, the effect of SNR was initially reversed for the second and third presentations: participants initially appeared to disengage in the harder SNR condition, resulting in reduced TEPRs that recovered in the second half of the story. Together, these findings suggest that the unfolding of listening effort over time depends critically on the extent to which individuals have successfully mobilized their attention in anticipation of difficult listening conditions. 

ABSTRACT We revisit the Quasar Main Sequence (QMS) by investigating the impact of the stellar component from the host galaxy (HG) on the emission line spectra of the active galactic nuclei (AGNs). We first detect spectra with broad emission lines using a line ratio method for a sample of $$\sim$$3000 high SNR ($>$20) black hole mapper objects (part of the fifth phase of the Sloan Digital Sky Survey). We then built the Index diagram, a novel diagnostic tool using the z-corrected spectra, model-free, designed to easily identify spectra with significant stellar HG contributions and to classify the AGN spectra into three categories based on AGN–HG dominance: HG-dominated (HGD), Intermediate (INT), and AGN-dominated (AGND) sources. A colour-z diagram was used to refine the AGN–HG classification. We subtract the stellar contributions from the HGD and INT spectra before modelling the AGN spectrum to extract the QMS parameters. Our QMS reveals that HGD galaxies predominantly occupy the Population B region with no R$$_{\rm {Fe\,{\small II}}}$$, with outliers exhibiting R$$_{\rm {Fe\,{\small II}}}$$  $>$ 1, likely due to HG subtraction residuals and a faint contribution of h$$\beta _{\rm BC}$$. INT and AGND spectra show similar distributions in the Population A region, while in Population B, a tail of AGND sources becomes apparent. Cross-matching with radio, infrared, and X-ray catalogues, we find that the strongest radio emitters are associated with HGD and INT groups. Strong X-ray emitters are found in INT and AGND sources, also occupying the AGN region in the Wide-field Infrared Survey Explorer colour diagram. 

Context.X-ray surveys combined with optical follow-up observations are used to generate complete flux-limited samples of the main X-ray emitting source classes. eROSITA on the Spectrum-Roentgen-Gamma mission provides sufficient sensitivity to build significantly enhanced samples of rare X-ray emitting sources. Aims.We strive to identify and classify compact white dwarf binaries, cataclysmic variables (CVs), and related objects, which were detected in the sky area of eFEDS, the eROSITA Final Equatorial Depths Survey, and they were observed in the plate program of SDSS-V. Methods.Compact white dwarf binaries were selected from spectra obtained in the early SDSS-V plate program. A dedicated set of SDSS plate observations were carried out in the eFEDS field, providing spectroscopic classifications for a significant fraction of the optically bright end (r< 22.5) of the X-ray sample. The identification and subclassification rests on visual inspections of the SDSS spectra, spectral variability, color-magnitude and color-color diagrams involving optical and X-ray fluxes, optical variability, and literature work. Results.Upon visual inspection of SDSS spectra and various auxiliary data products, we have identified 26 accreting compact white dwarf binaries (aCWDBs) in eFEDS, of which 24 are proven X-ray emitters. Among those 26 objects, there are 12 dwarf novae, three WZ Sge-like disk-accreting nonmagnetic CVs with low accretion rates, five likely nonmagnetic high accretion rate nova-like CVs, two magnetic CVs of the polar subcategory, and three double degenerates (AM CVn objects). Period bouncing candidates and magnetic systems are rarer than expected in this sample, but it is too small for a thorough statistical analysis. Fourteen of the systems are new discoveries, of which five are fainter than theGaiamagnitude limit. Thirteen aCWDBs have measured or estimated orbital periods, of which five were presented here. Through a Zeeman analysis, we revise the magnetic field estimate of the polar system J0926+0105, which is likely a low-field polar atB= 16 MG. We quantified the success of X-ray versus optical/UV selection of compact white dwarf binaries which will be relevant for the full SDSS-V survey. We also identified six white dwarf main sequence (WDMS) systems, among them there is one confirmed pre-CV at an orbital period of 17.6 h and another pre-CV candidate. Conclusions.This work presents successful initial work in building large samples of all kinds of accreting and X-ray emitting compact white dwarf binaries that will be continued over the full hemisphere in the years to come.