High-resolution Spectra Research Articles

The ESO SupJup Survey. VIII. Chemical fingerprints of young L dwarf twins

The potentially distinct formation pathways of exoplanets and brown dwarfs may be imprinted in their elemental and isotopic ratios. This work is part of the ESO SupJup Survey, which aims to disentangle the formation pathways of super-Jupiters and brown dwarfs through the analysis of their chemical and isotopic ratios. In this study, we aim to characterize the atmospheres of two young L4 dwarfs, 2MASS J03552337+1133437 (2M0355) and 2MASS J14252798-3650229 (2M1425), in the AB Doradus Moving Group. This involved constraining their chemical composition, ^12CO/^13CO ratio, pressure-temperature profile, surface gravity, and rotational velocity, among other parameters. We have obtained high-resolution CRIRES+ K-band spectra of these brown dwarfs, which we analyzed with an atmospheric retrieval pipeline. Atmospheric models were generated with the radiative transfer code petitRADTRANS for which we employed a free and equilibrium chemistry approach, which we coupled with the PyMultiNest sampling algorithm to determine the best fit. We report robust detections of ^13CO (13.4 8.0,σ) and HF (11.6 15.8,σ) in 2M0355 and 2M1425, respectively. The objects have similar overall atmospheric properties, including ^12CO/^13CO isotope ratios of 95.5 -6.4 for 2M0355 and 109.6 -9.6 for 2M1425. The most notable difference is the robust evidence of CH_4 (5.5,σ) but no H_2S (<,2.3,σ) in 2M1425, in contrast to 2M0355, for which we retrieved H_2S (4.6,σ) but not CH_4 (<,2.2,σ). We also find tentative hints of NH_3 in 2M1425 (3.0,σ). In both brown dwarfs, we find only tentative hints of H_2^18O (1.1 3.0,σ), with lower limits of H_2^16O/H_2^18O,∼,1000. Both objects appear to be close to chemical equilibrium, considering the main spectral contributors. We also find that 2M1425 is 50--200 K hotter than 2M0355 and has a higher surface gravity. Retrievals of high-resolution K-band spectra of young brown dwarfs enable a detailed insight into their atmospheres. As with similar targets, these brown dwarfs also exhibit a depletion of ^13CO compared to the interstellar medium. Future studies will put them into the context of other objects observed as part of the ESO SupJup Survey.

Rapidly Varying Ionization Features in a Quasi-periodic Eruption: A Homologous Expansion Model for the Spectroscopic Evolution

Abstract Quasi-periodic eruptions (QPEs) are recurring bursts of soft X-ray emission from supermassive black holes, which a growing class of models explains via extreme mass ratio inspirals (EMRIs). QPEs exhibit blackbody-like emission with significant temperature evolution, but the minimal information content of their almost pure-thermal spectra has limited physical constraints. Here we study the recently discovered QPEs in ZTF19acnskyy (“Ansky”), which show absorption-like features evolving dramatically within eruptions and correlating strongly with continuum temperature and luminosity, further probing the conditions underlying the emission surface. The absorption features are well described by dense ionized plasma of column density N H ≳ 1021 cm−2, blueshift 0.06 ≲ v/c ≲ 0.4, and either collisional or photoionization equilibrium. With high-resolution spectra, we also detect ionized blueshifted emission lines suggesting a nitrogen overabundance of 21 . 7 − 11.0 + 18.5 × solar. We interpret our results with orbiter–disk collisions in an EMRI system, in which each impact drives a shock that locally heats the disk and expels X-ray-emitting debris undergoing radiation-pressure-driven homologous expansion. We explore an analytical toy model that links the rapid change in absorption lines to the evolution of the ionization parameter and the photosphere radius, and we suggest that ∼10−3 M ⊙ ejected per eruption with expansion velocities up to v max ∼ 0.15 c can reproduce the absorption features. With these assumptions, we show that a P Cygni profile in a spherical expansion geometry qualitatively matches the observed line profiles. Our work takes a first step toward extending existing physical models for QPEs to address their implications for spectral line formation.

Epimeric Macrolactin Analogs From a Marine-Derived Bacillus velezensis Against Herpesvirus.

Two new glycosylated macrolides (1, 2), along with five known compounds (3-7) were isolated from an endophytic bacterium of Bacillus velezensis inhabiting the mangrove plant Acanthus ilicifolius L. Compound 1 is a 24-membered macrolide featuring a 7-OH glycosylation and a 6'-succinate ester, the C-7 epimer of macrolactin D, while compound 2 is the 7-position epimer of macrolactin B, as determined through comprehensive analysis of one-dimensional and two-dimensional nuclear magnetic resonance, and high-resolution electrospray ionization mass spectra spectroscopic data, as well as chemical transformation. In addition, compounds 1 and 2 exhibit significant antiviral activity against herpesvirus as determined by quantitative real-time polymerase chain reaction and Western Blot assay. At the messenger RNA level, compounds 1 and 2 achieved about 85% inhibition at 5 µg/mL, almost equivalent to the positive control of acyclovir.

Antileishmanial activity of Ptilostemon chamaepeuce subsp. cyprius.

Antileishmanial activity of Ptilostemon chamaepeuce subsp. cyprius.

Barium Abundances from the LAMOST Medium-Resolution Survey Stellar Spectra

Abstract Based on a template-matching method, we estimate the barium (Ba) abundances for stellar spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Medium-Resolution Spectroscopic Survey (MRS). The Ba abundances of 198,011 stars have been determined from MRS spectra with signal-to-noise ratios (S/N) > 40 combined with the stellar atmospheric parameters from the LAMOST Low-Resolution Spectroscopic Survey DR9 by the LAMOST Stellar Parameter Pipeline. The uncertainties in the Ba abundances from the LAMOST MRS spectra are less than 0.3 dex when S/N exceeds 40, which align closely with the results based on the high-resolution UVES spectra from the Gaia-ESO survey obtained by spectral synthesis. Further analysis of Ba abundances from repeated observations of the same stars reveals that random errors related to spectral quality remain below 0.3 dex at the same S/N, with a systematic overestimation for the low-S/N spectra. This extensive sample of stellar Ba abundances will enhance studies of the s-, i-, and r-processes, and deepen our understanding of the chemical-evolution history of the Milky Way.

Volume-limited sample of low-mass red giant stars, the progenitors of hot subdwarf stars

Context. Binary hot subdwarf B (sdB) stars are typically produced from low-mass red giant branch (RGB) stars that have lost almost all their envelopes through binary mass transfer while still fusing helium in their cores. Particularly, when a low-mass red giant enters stable Roche lobe overflow (RLOF) mass transfer near the tip of the RGB, a long-period sdB binary may be formed. Aims. We aim to extend our previous volume-limited sample of 211 stars within 200 pc, a homogeneous sample of low-mass red giants, predicted progenitors of wide sdB binaries, to 500 pc and validate it. Additionally, our goal is to provide the distribution of stellar parameters for these stars. Methods. We refined our original 500 pc sample by incorporating Gaia DR3 parallax values and interstellar extinction measurements. Next, we collected multi-epoch high-resolution spectra for 230 stars in the volume-limited sample using the CORALIE échelle spectrograph from 2019 to 2023. To confirm or discard binarity, we combined astrometric parameters from Gaia with the resulting radial velocity variations. We derived the distribution of stellar parameters using evolutionary models and employed the equivalent evolutionary phase to verify the evolutionary stage of the stars in our sample. Finally, we compared our stellar parameters with the literature. Results. The derived stellar parameters confirmed that 82% of stars in our sample are indeed in the RGB phase, while 18% are red clump (RC) contaminants. This was expected due to the overlapping of RGB and RC stars in the colour-magnitude diagram. Additionally, 75% of the confirmed RGB stars have a high probability of being part of a binary system. Comparison with the literature shows good overall agreement with a scatter ≲15% in stellar parameters, while the masses show somewhat higher dispersion (∼20%). Conclusions. We have obtained the most complete volume-limited sample of binary RGB star candidates within 500 pc. These systems are likely progenitors of hot subdwarfs and other classes of stripped helium stars.

Measurement of Methane Line Broadening in Hot Hydrogen/Helium Atmospheres at λ = 1.60–1.63 μm for Substellar Object Spectroscopy

Abstract Recent high-dispersion spectroscopy from ground-based telescopes and high-precision spectroscopy from space observatories have enabled atmospheric observations of substellar objects, such as brown dwarfs and hot gaseous exoplanets, with sufficient precision to make ambient gas differences in molecular line broadening a significant factor. In this paper, we experimentally measured the pressure broadening of methane in a high-temperature hydrogen–helium background atmosphere in the H band, which had not been previously measured. The experiment used glass cells, inserted in a tube furnace, filled with methane in a hydrogen–helium background atmosphere or pure methane gas. Spectra were obtained at four temperatures ranging from room temperature to 1000 K, in the wavelength range 1.60–1.63 μm, using a tunable laser, yielding eight high-resolution spectra in total. A full Bayesian analysis was performed on the obtained spectra, using the differentiable spectral model ExoJAX and the Hamiltonian Monte Carlo for inferring a large number of parameters, allowing us to infer the H2/He pressure broadening for 22 transitions mainly in the R branch of the 2ν 3 band. As a result, we found a temperature exponent of approximately 0.27 and a reference width at 296 K of around 0.040 for J lower = 13–20. This temperature dependency is much milder than that provided by the molecular database ExoMol, yielding a line width approximately 5%–45% smaller than ExoMol at 296 K, but similar at 1000 K. Our results suggest the need for further accumulation of experimental data for spectral analysis of substellar objects with hydrogen–helium atmospheres.

The Effects of Kinematic Magnetohydrodynamics on the Atmospheric Circulation of Eccentric Hot Jupiters

Abstract Hot Jupiters are typically considered to be tidally locked due to their short orbital periods. The extreme irradiation can result in atmospheric species becoming thermally ionized on the dayside, which then interact with the planet’s magnetic field by resisting flow across magnetic field lines, shaping the atmospheric structure. However, an eccentric orbit results in temporally dependent irradiation and a nonpermanent dayside, as the planet–star distance can change drastically during its orbit. In this paper, we present 3D atmospheric models of TOI-150b, an eccentric (e = 0.26), Jupiter-mass (∼1.75M Jup) planet whose equilibrium temperature varies from 1300 to 1700 K. We conduct simulations for magnetic field strengths ranging from 0 to 30 Gauss using the kinematic magnetohydrodynamics (MHD) approach. When compared with simulations of the planet assuming a circular orbit, we find that the eccentric orbit results in a strengthened and narrowed equatorial jet, westward winds at midlatitudes, and a phase-dependent thermal inversion. The strength and magnitude of these effects scale with the chosen global magnetic field strength. We also generate high-resolution (R = 100,000) emission spectra to study net Doppler shifts and find interorbit spectroscopic variability at moderate magnetic field strengths, as well as decreased Doppler broadening as magnetic field strengths increase. This work represents the first time that the kinematic MHD approach has been applied to an eccentric hot Jupiter and highlights the importance of a locally calculated, temperature-dependent magnetic drag prescription for predicting atmospheric structure and resulting spectra.

Comprehensive UV and optical spectral analysis of Cygnus X-1. Stellar and wind parameters, abundances, and evolutionary implications

Cygnus X-1 contains the only dynamically confirmed black hole in a persistent high-mass X-ray binary in the Milky Way. Previous studies have suggested that the black hole in Cyg,X-1 is one of the most massive stellar-mass black holes known in an X-ray binary, despite its high-metallicity environment. While the source has been actively investigated, a comprehensive UV and optical spectral analysis of the donor using modern stellar atmosphere models incorporating stellar winds and X-ray ionization has been lacking. We aim to determine the stellar parameters, chemical abundances, and wind parameters of the donor star in Cyg,X-1 along with the mass of the black hole. We also aim to investigate the system's current evolutionary state and its future evolution toward a binary black hole system, exploring its potential as a gravitational wave source. We used archival high-resolution UV and optical spectra of Cyg,X-1 taken at multiple orbital phases and X-ray states. We employed state-of-the-art, non-local thermodynamic equilibrium (non-LTE), Potsdam Wolf-Rayet (PoWR) atmosphere models that account for stellar winds, X-ray photoionization, metal line blanketing, and wind clumping. We performed a simultaneous analysis of UV and optical spectra. We further used the stellar evolution code MESA to model the further evolution of the system. Our analysis yields notably lower masses for both the donor (≈ 29,M_⊙) and the black hole ($12.7$ to $17.8,M_⊙$, depending on inclination), and confirms that the donor's radius is close to reaching the inner Lagrangian point. We find super-solar Fe, Si, and Mg abundances (1.3-1.8 times solar) at the surface of the donor star, while the total CNO abundance remains solar despite evidence of CNO processing (N enrichment, O depletion) and He enrichment. This abundance pattern is distinct from the surrounding Cyg OB3 association. We observed a clear difference in wind parameters between X-ray states: varv_∞ ≈ 1200 km,s and dot M ≈ 3 M_⊙ yr in the high-soft state, increasing to varv_∞ km,s and dot M M_⊙ yr in the low-hard state. The observed X-ray luminosity is consistent with wind-fed accretion. Evolutionary models show that Cyg,X-1 will undergo Roche-lobe overflow in the near future. Under a fully conservative mass accretion scenario, our models predict a future binary black hole merger for Cyg,X-1 within ∼5 Gyr. Our comprehensive analysis provides refined stellar and wind parameters of the donor star in Cyg,X-1 highlighting the importance of using advanced atmospheric models and considering X-ray ionization and wind clumping. The observed abundances suggest a complex formation history involving a high initial metallicity. The potential for a future gravitational wave merger under highly conservative mass accretion makes Cyg X-1 crucial for understanding binary evolution.

SlitNET: A Deep Learning Enabled Spectrometer Slit.

The efficiency and resolution of dispersive spectrometers play crucial roles in optical spectroscopy. Achieving optimal analytical performance in optical spectroscopy requires striking a delicate balance between employing a narrow spectrometer input slit to enhance spectral resolution while sacrificing throughput or utilizing a wider slit to increase throughput at the expense of resolution. Here, we introduce a spectrometer slit empowered by a deep learning model SlitNET. We trained a neural network to reconstruct synthetic Raman spectra with enhanced resolution from low-resolution inputs. Subsequently, we performed transfer learning from synthetic data to experimental Raman data of materials. By fine-tuning the model with experimental data, we recovered high-resolution Raman spectra. This enhancement enabled us to distinguish between materials that were previously indistinguishable when using a wide slit. SlitNET achieved a resolution enhancement equivalent to employing a 10 μm slit size but with a physical input slit of 100 μm. This, in turn, enables us to simultaneously achieve high throughput and resolution, thereby enhancing the analytic sensitivity and specificity in optical spectroscopy. The incorporation of deep learning into spectrometers highlights the convergence of photonic instrumentation and artificial intelligence, offering improved measurement accuracy across various optical spectroscopy applications.

Anomalous Radio Signal Detection Based on an Adversarial Autoencoder

In complex and ever-changing electromagnetic environments, a large number of anomalous radio signals illegally occupy spectrum resources and interfere with legitimate communications. To address this challenge, this paper proposes an anomalous radio signal detection method based on an Adversarial Autoencoder (AAE). The method comprises an autoencoder and a Generative Adversarial Network. The autoencoder is used to extract time–frequency features of radio signals, generate latent feature vectors, and reconstruct the signals. By comparing the original signals to their reconstructions, anomalies can be rapidly and accurately detected via the reconstruction error. Meanwhile, the adversarial network regularizes the latent vectors produced by the encoder, forcing them to approximate a predefined prior distribution, thereby improving the model’s generative capability and enhancing the structural consistency of the latent representations. We used a Pluto SDR device to capture real-world radio data in the field, performed frequency-domain analysis, and constructed a high-resolution power spectrum time–frequency dataset for model training and testing. Experimental results show that the proposed method achieves a detection accuracy of 95.5% for anomalous radio signals, exhibiting excellent performance on multiple metrics across diverse scenarios.

Bimetallic AuPd alloy nanoparticles on TiO2 nanotube arrays: a highly efficient photocatalyst for hydrogen generation

Decoration of TiO2nanotube (TNT) arrays by AuPd nanoparticles (NPs) produces a dramatic enhancement in the rate of hydrogen generation through photocatalytic water-splitting under solar illumination. XRD and TEM confirmed alloy formation in bimetallic AuPd NPs while XPS ruled out a core-shell architecture in the AuPd NPs. Well-dispersed, size-controlled AuPd NPs were formed by sequential physical vapor deposition of Au and Pd on TNTs followed by spontaneous thermal dewetting (TNT-AuPd). TNT-AuPd samples were characterized by small tensile microstrains. For comparison purposes and to derive physical insights, an identical method was used to form TNT-Au and TNT-Pd samples wherein TNTs were decorated by monometallic Au and Pd NPs respectively. In every case, an accumulation-type heterointerface between TiO2and the metallic/bimetallic NPs was indicated by binding energy shifts in the Ti2p high-resolution x-ray photoelectron spectra (HR-XPS). Initial and final state effects in the Au4f HR-XPS pointed to a large number of Au atoms in low coordinate sites such as edges, kinks and corners as well as a slower excited atom relaxation in the alloy. A similar preponderance of Pd atoms at low coordinate sites was found along with the presence of a small amount of palladium oxide. The alloying of Au with a low Pd content on TNT yields significant enhancement in hydrogen production under UV-visible light in aqueous triethanolamine solutions. TNT-AuPd demonstrated the highest photocatalytic H2production rate of 2920µmol g-1h-1, which is 8.9 times higher than that of TNTs, 2.1 times that of TNT-Au, and 1.69 times that of TNT-Pd under solar illumination. We studied H2generation under UV-filtered solar illumination with TNT-AuPd outperforming monometallic Au- and Pd-NP decorated TNTs, which is attributed to the enhancement of the catalytic activity of Pd in an Au environment, the presence of Pd and Au atoms at low coordinate sites, and photoinduced electron transfer between TNTs and AuPd alloy NPs, where AuPd acts as an efficient electron sink, in turn reducing carrier recombination losses. AuPd bimetallic nanoparticles on TNTs, prepared via a simple anodization and vapor deposition method, exhibit excellent stability across multiple cycles and offer valuable insights for the development of efficient photocatalysts with promising potential for emerging energy applications.

Rapid Acquisition of 103Rh Solid-State NMR Spectra by 31P Detection and Sideband Selective Methods.

103Rh solid-state nuclear magnetic resonance (SSNMR) spectroscopy is potentially a powerful method for investigating the molecular and electronic structure of rhodium compounds. However, 103Rh is a difficult nucleus to study by NMR spectroscopy because of its small gyromagnetic ratio, broad chemical shift range, and long spin-lattice relaxation times (T1). While there are many prior reports demonstrating acquisition of 103Rh solution NMR spectra, there are few examples of 103Rh SSNMR spectra in the literature. Here, we utilize the large 31P-103Rh scalar couplings (J-couplings) to efficiently acquire 31P-detected high-resolution 103Rh SSNMR spectra. 31P{103Rh} J-resolved NMR experiments were used to measure 31P-103Rh J-couplings. Sideband selective SSNMR techniques originally developed for wide-line 195Pt SSNMR experiments were then used to rapidly acquire 103Rh SSNMR spectra. Notably, we were able to acquire MAS 103Rh SSNMR spectra in experiment times on the order of 30 min to a few hours and from only a few mg of materials. The sideband selective experiments offer significant time savings as compared to existing direct detection methods, which require days of acquisition to obtain a directly detected MAS spectrum, or yield low-resolution static powder patterns. Numerical fits of the SSNMR spectra provide 103Rh chemical shift tensor parameters, with the experimental spectra agreeing well with the DFT-calculated spectra.

A Systematic NLTE Study of Very Metal-poor Stars with Metallicity down to −4.3 dex. I. Global Stellar Parameters Based on High-resolution Spectra

A Systematic NLTE Study of Very Metal-poor Stars with Metallicity down to −4.3 dex. I. Global Stellar Parameters Based on High-resolution Spectra

Exploring Vinylidene/Acetylene Isomerization by Photoelectron Spectroscopy of Vibrationally Excited Vinylidene Anions.

In order to explore the vibrational levels of vinylidene (H2CC) and their possible couplings with acetylene (HCCH), we investigate the effect of infrared (IR) vibrational pre-excitation on the high-resolution photoelectron spectra of the vinylidene anion (H2CC-) and its deuterated isotopologue (D2CC-). The photoelectron spectra are obtained using slow electron velocity-map imaging of cryogenically cooled anions (cryo-SEVI); here, cold anions are vibrationally excited by an IR laser pulse prior to photodetachment (IR cryo-SEVI). Infrared action spectra of the anion CH2 stretching fundamentals are measured by monitoring growth and depletion of features in photoelectron spectra as the IR laser is tuned, yielding excitation frequencies of the symmetric (ν1) and antisymmetric (ν5) CH2 stretching modes of 2590 ± 2 and 2658 ± 2 cm-1, respectively. We then use IR cryo-SEVI to explore the effect of vibrational excitation of the two modes on the anion photoelectron spectrum. Interpretation of these spectra is facilitated by quantum calculations performed for each isotopologue on accurate six-dimensional potential energy surfaces of both neutral and anionic vinylidene. IR cryo-SEVI spectra resulting from excitation of these two close-lying anion vibrations are noticeably different. Excitation of the ν1 mode leads to several new features that appear in the photoelectron spectra which closely match the Franck-Condon allowed transitions predicted by theory. Excitation of the ν5 mode in H2CC- reveals complicated spectral features in the vicinity of the 511 sequence band that are not seen for D2CC-. These are explained by a combination of anharmonic coupling between ν5 and ν6 (CH2 rock) states in neutral H2CC and possible coupling to the HCCH isomer.

A new aggregation and riming discrimination algorithm based on polarimetric weather radars

Abstract. The distinction between riming and aggregation is of high relevance for model microphysics, data assimilation, and warnings of potential aircraft hazards due to the link between riming and updrafts as well as the presence of supercooled liquid water in the atmosphere. Even though the polarimetric fingerprints for aggregation and riming are qualitatively similar, we hypothesize that it is feasible to implement an area-wide discrimination algorithm based on national polarimetric weather radar networks only. Quasi-vertical profiles (QVPs) of reflectivity (ZH), differential reflectivity (ZDR), and estimated depolarization ratio (DR) are utilized to learn about the information content of each individual polarimetric variable and their combinations for riming detection. High-resolution Doppler spectra from the vertical (birdbath) scans of the C-band radar network of the German Meteorological Service serve as input and ground truth for algorithm development. Mean isolated spectra profiles (MISPs) of the Doppler velocity are used to infer regions with frozen hydrometeors falling faster than 1.5 m s−1 and accordingly associated with significant riming. Several machine learning methods have been tested to detect riming from the corresponding QVPs of polarimetric variables. The best-performing algorithm is a fine-tuned gradient-boosting model based on decision trees. The precipitation event on 14 July 2021, which led to catastrophic flooding in the Ahr valley in western Germany, was selected to validate the performance. Considering balanced accuracy, the algorithm is able to correctly predict 74 % of the observed riming features; thus, the feasibility of reliable riming detection with national radar networks has been successfully demonstrated.

The enigmatic magnetic field of the planet hosting Herbig Ae/Be star HD 169142

Recent observations of the accretion disk around the Herbig Ae/Be star HD,169142 have revealed its complex and asymmetric morphology that indicates the presence of planets. The knowledge of the magnetic field structure in host stars is indispensable for our understanding of the magnetospheric interaction between the central stars, the circumstellar (CS) environment, and the planetary companions. We want to study the geometry of the magnetic field of HD,169142. We measured the mean longitudinal magnetic field from high-resolution ESPaDOnS and HARPS-pol spectra of HD,169142 using the least-squares deconvolution technique. Additionally, the spectral variability of hydrogen lines is studied using dynamical spectra. Our analysis of the Stokes V spectra reveals the presence of definitely detected narrow Zeeman features observed using line masks with neutral iron lines. On two observing epochs, we also obtain marginally detected broad Zeeman features. To explain the simultaneous appearance of narrow and broad Zeeman features, we discuss different scenarios, including one scenario related to a non-photospheric origin of the narrow Zeeman features due to magnetospheric interaction with warm CS matter. In an environment such as a wind or an accretion disk, spectral lines may form over a relatively large volume, and the field topology may therefore be complex not only in latitude and azimuth, but in radius as well. Dynamical plots of the Hβ line show an intriguing very complex structure with appearing and disappearing absorption features, which can be related to the complex morphology of the CS matter with asymmetric dust clump structures. The profiles of spectral lines belonging to different elements are variable, indicating the presence of chemical spots.

A Sequoia stellar candidate with very high 7Li and 9Be

The metal-poor star BPM,3066 belongs to the retrograde halo and presents unexpectedly strong spectral features of lithium. To gain insight into the origin of this peculiar abundance, we investigate the chemistry and kinematic properties of this star. We performed a local thermodynamic equilibrium chemical abundance analysis of UVES/VLT high-resolution spectra of BPM,3066 using ATLAS9 and ATLAS12 model atmospheres and the MyGIsFOS code. We further characterised the orbital properties of the star by integrating its orbit and analysing its integrals of motion using the galpy code. The star BPM,3066 shows an exceptional overabundance of both lithium and beryllium. The abundances are A(Li) = 3.0 and A(Be) = 2.1, which are respectively about 0.8 and 2.2 dex higher than the Li and Be abundances expected at Fe/H = -1.5, the metallicity of the star. The observed ratio ^7Li/^9Be is 7.9, which is close to that expected from a synthesis by spallation processes. Overabundances of Si, Al, and of the neutron capture elements Sr,Y, Zr, and Ba are also measured. Kinematically, BPM,3066 has an eccentric, strongly retrograde orbit, confined to a height lower than 1,kpc from the galactic plane, and it is a candidate member of the Sequoia/Thamnos accreted galaxy. The processes leading to the ^7Li and ^9Be synthesis could have occurred in the environment of a hypernova. This is supported by some abundance anomalies like the high value of Si Si/Fe =1.2 and Si/O =1.1. However, the simultaneous high values of N, Na, Al, Sc, Ti, and Cu are at odds with the expectations from a hypernova. Alternatively, the abundances of BPM,3066 could result from the engulfing of rocky planets that were rich in spallated Li and Be. In both cases, it is remarkable that such an extreme abundance pattern has been found in a star belonging to the Sequoia/Thamnos accreted galaxy.

HIP 8522: A Puzzling Young Solar Twin with the Lowest Detected Lithium Abundance**This research is based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan (NAOJ). We are honored and grateful for the opportunity of observing the Universe from the Maunakea, which has cultural, historical, and natural significance in Hawaii. This paper

Abstract We present HIP 8522, a young solar twin with the lowest detected lithium abundance, potentially a field blue straggler or the result of episodic early accretion. Its stellar parameters (T eff = 5729 ± 7 K, log g = 4.532 ± 0.016 dex, [Fe/H] = 0.005 ± 0.010 dex, and v t = 1.08 ± 0.02 km s−1) and chemical composition were determined via spectroscopic equilibrium using high-resolution spectra (R = 60,000–165,000). The age of HIP 8522 was estimated to have an upper limit of <1 Gyr through isochrone fitting and was further confirmed using chemical clocks. Spectral synthesis of the lithium line at ∼6707.8 Å yielded an upper lithium abundance limit of A(Li) < 0.8 dex. This value is unusually low for solar twins of similar age, which typically have A(Li) values ranging from 2.0 to 3.3 dex, suggesting that ∼2 dex of lithium is missing. We investigate various scenarios, such as planet engulfment, substellar mergers, and extra mixing. However, two distinct hypotheses provide plausible explanations for the significant depletion of lithium: one suggests that HIP 8522 is a field blue straggler formed by the merger of a close binary, while the other proposes that HIP 8522 experienced early episodic accretion. The young solar twin HIP 8522 presents an exceptional opportunity to rigorously test stellar evolution models and gain crucial insights into the internal mixing mechanisms responsible for the significant destruction of lithium.

Pollution Risk Assessment of Potentially Toxic Elements in Soils Using Characterization and Microbiological Analysis: The Case of a Rare and Precious Metal Mining Site in Wuzhou, Guangxi.

To understand the characteristics of the pollution risk of potentially toxic elements (PTEs) at a rare and precious metal mining site in Guangxi and to provide scientific evidence for the comprehensive evaluation and soil remediation of PTE pollution at the site, the Cd, As, Co, Cu, Cr, Ni, Pb, and Zn contents of five areas were determined. Laboratory testing was conducted on five soil plots in the selected five suspected contaminated areas (electroplating workshop, sewage treatment area, and boiler room). Correlation analysis, infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to evaluate and analyze PTE pollution. The average contents of Cd, Co, As, Pb, Zn, and Cu at the site were higher than the background values in the Guangxi soil. The Probability Mass Function (PMF) model was used to perform a source apportionment of the PTEs and determine the main pollution sources and their contribution rates. The results of the single factor pollution of the PTEs showed that Cd, Ar, and Cr were heavy pollutants, and Co was a light pollutant. The Nemerow comprehensive pollution index analysis showed that the study area was heavily polluted. The Earth accumulation index results show that Cd exhibited a very serious accumulation, Cu and Zn exhibited mild to moderate accumulations, and As and Co exhibited moderate accumulations. The FTIR results showed that C=O in the soil was chelated with PTEs in some samples, which weakened the characteristic peaks of C=O in proteins and polypeptides. The XRD results showed that cadmium hydroxide, lead oxide, and zinc hydroxide were present in the soil samples. The XPS results showed that the production of O2- in the O 1s high-resolution spectra mainly came from the metal oxides produced by the polluting metals. Meanwhile, the microbial results showed that the pollution risk of PTEs affected the soil microbial community structure and diversity to some extent.