bluuebunny/crossref_metadata_2025 huggingface dataset:
A perturbative treatment of the Yarkovsky-driven drifts in the 2:1 mean motion resonance
Authors: Tan Pan , Hou Xi-Yun
Published: July 2024

Aims. Our aim is to gain a qualitative understanding as well as to perform a quantitative analysis of the interplay between the Yarkovsky effect and the Jovian 2:1 mean motion resonance under the planar elliptic restricted three-body problem.

Methods. We adopted the semi-analytical perturbation method valid for arbitrary eccentricity to obtain the resonance structures inside the Jovian 2:1 resonance. We averaged the Yarkovsky force so it could be applied to the integrable approximations for the 2:1 resonance and the ν5 secular resonance. The rates of Yarkovsky-driven drifts in the action space were derived from the quasi-integrable approximations perturbed by the averaged Yarkovsky force. Pseudo-proper elements of test particles inside the 2:1 resonance were computed using N-body simulations incorporated with the Yarkovsky effect to verify the semi-analytical results.

Results. In the planar elliptic restricted model, we identified two main types of systematic drifts in the action space: (Type I) for orbits not trapped in the ν5 resonance, the footprints are parallel to the resonance curve of the stable center of the 2:1 resonance; (Type II) for orbits trapped in the ν5 resonance, the footprints are parallel to the resonance curve of the stable center of the ν5 resonance. Using the semi-analytical perturbation method, a vector field in the action space corresponding to the two types of systematic drifts was derived. The Type I drift with small eccentricities and small libration amplitudes of 2:1 resonance can be modeled by a harmonic oscillator with a slowly varying parameter, for which an analytical treatment using the adiabatic invariant theory was carried out.
The ESO SupJup Survey
Authors: González Picos D. , Snellen I. A. G. , de Regt S. , Landman R. , Zhang Y. , Gandhi S. , Ginski C. , Kesseli A. Y. , Mollière P. , Stolker T.
Published: July 2024

Context. Young brown dwarfs exhibit atmospheric characteristics similar to those of super-Jupiters, providing a unique opportunity to study planetary atmospheres. Atmospheric retrievals of high-resolution spectra reveal detailed properties of these objects, with elemental and isotopic ratios offering insights into their formation history. The ESO SupJup Survey, utilising CRIRES+ on the Very Large Telescope, aims to assess the role of 12C/13C as a formation tracer.

Aims. We present observations of three young brown dwarfs: 2MASS J12003792-7845082, TWA 28, and 2MASS J08561384-1342242. Our goal is to constrain their chemical compositions, thermal profiles, surface gravities, spin rotations, and 12C/13C.

Methods. We conducted atmospheric retrievals of CRIRES+ K-band spectra, coupling the radiative transfer code petitRADTRANS with the Bayesian inference algorithm MultiNest.

Results. The retrievals provide a detailed characterisation of the atmospheres of the three objects. We report the volume mixing ratios of the main molecular and atomic species: H216O,12CO, HF, Na, Ca, and Ti, including the novel detection of hydrogen fluoride (HF) in the atmosphere of a brown dwarf. We determine 12C/13C values of 81−19+28 and 79−14+20 in the atmospheres of TWA 28 and J0856, respectively, with strong significance (>3σ). We also report tentative evidence (~2σ) of 13CO in J1200, at 12C/13C = 114−33+69. Additionally, we detect H218O at moderate significance in J0856 (3.3σ) and TWA 28 (2.1σ). The retrieved thermal profiles are consistent with hot atmospheres (2300–2600 K) with low surface gravities and slow spins, as expected for young objects.

Conclusions. The measured carbon isotope ratios are consistent among the three objects and show no significant deviation from that of the local interstellar medium, suggesting a fragmentation-based formation mechanism similar to star formation. The tentative detection of H218O in two objects of our sample highlights the potential of high-resolution spectroscopy to probe additional isotope ratios, such as 16O/18O, in the atmospheres of brown dwarfs and super-Jupiters.
Lopsided distribution of MATLAS and ELVES dwarf satellite systems around isolated host galaxies
Authors: Heesters Nick , Jerjen Helmut , Müller Oliver , Pawlowski Marcel S. , Jamie Kanehisa Kosuke
Published: July 2024

The properties of satellite dwarf galaxies provide important empirical insights for verifying cosmological models on galaxy scales. Their phase-space correlations, in particular, offer interesting insights into a broad range of models, since they are dominated by gravity and are largely independent of the specific dark matter flavor or baryonic processes that are considered. Next to the much-debated planes-of-satellites phenomenon, the lopsided distribution of satellites relative to their host galaxy has been studied observationally and in cosmological simulations. The degree to which observed lopsidedness is consistent with expectations from simulations is still unclear. We quantified the level of lopsidedness in isolated observed satellite systems under six different metrics. We studied 47 systems from the MATLAS survey beyond the local volume (LV) as well as 21 LV satellite systems from the ELVES survey. The satellite systems are complete to an estimated absolute magnitude of M ∼ −9. We find that the so-called wedge metric, counting the number of dwarfs in wedges with varying opening angles, is best suited to capture a system’s overall lopsidedness. Under this metric, our analysis reveals that ∼16 percent of the tested satellite systems exhibit a statistically significant degree of lopsidedness when compared to systems with randomly generated satellite position angles. This presents a notable excess over the expected 5% (2σ level) of significantly lopsided systems in a sample with no overall inherent lopsidedness. To gain the most rounded picture, however, a combination of metrics that are sensitive to different features of lopsidedness should be used. Combining all tested metrics, the number of significantly lopsided systems increases to ∼21 percent. Contrary to recent results from the literature, we find more lopsided systems among the red early-type galaxies in the MATLAS survey compared to the mostly blue late-type hosts in ELVES. We further find that satellite galaxies at larger distances from the host, potentially recently accreted, are likely the primary contributors to the reported excess of lopsidedness. Our results set the groundwork that allows a comparison with similar systems in cosmological simulations to assess the consistency with the standard model.
Revisiting Jupiter’s deuterium fraction in the rotational ground-state line of HD at high spectral resolution
Authors: Wiesemeyer Helmut , Güsten Rolf , Hartogh Paul , Okada Yoko , Ricken Oliver , Stutzki Jürgen
Published: July 2024

The cosmic deuterium fraction, set by primordial nucleosynthesis and diminished by subsequent astration, is a valuable diagnostic tool to link the protosolar nebula to the history of star formation. However, in the present-day Solar System, the deuterium fraction in various carriers varies by more than an order of magnitude and reflects environmental conditions rather than the protosolar value. The latter is believed to be preserved in the atmospheres of the gas giant planets, yet determinations inferred from the CH3D/CH4 pair require a larger fractionation correction than those from HD/H2, which are close to unity. The question of whether a stratospheric emission feature contaminates the absorption profile forming in subjacent layers was never addressed, owing to the lack of spectral resolving power. Here we report on the determination of the Jovian deuterium fraction using the rotational ground-state line of HD (J = 1–0) at λ112 μm. Employing the GREAT heterodyne spectrometer on board SOFIA, we detected the HD absorption and, thanks to the high resolving power, a weak stratospheric emission feature underneath; the former is blue-shifted with respect to the latter. The displacement is attributed to a pressure-induced line shift and reproduced by dedicated radiative-transfer modeling based on recent line-profile parameters. Using atmospheric standard models, we obtained D/H = (1.9 ± 0.4) × 10−5, which agrees with a recent measurement in Saturn’s atmosphere and with the value inferred from solar-wind measurements and meteoritic data. The result suggests that all three measurements represent bona fide protosolar D/H fractions. As a supplement and test for the consistency of the layering assumed in our model, we provide an analysis of the purely rotational J = 6–5 line of CH4 (in the vibrational ground state, at λ 159 μm).
Investigating the off-axis GRB afterglow scenario for extragalactic fast X-ray transients
Authors: Wichern H. C. I. , Ravasio M. E. , Jonker P. G. , Quirola-Vásquez J. A. , Levan A. J. , Bauer F. E. , Kann D. A.
Published: July 2024

Context. Extragalactic fast X-ray transients (FXTs) are short-duration (∼ks) X-ray flashes of unknown origin, potentially arising from binary neutron star (BNS) mergers, tidal disruption events, or supernova shock breakouts.

Aims. In the context of the BNS scenario, we investigate the possible link between FXTs and the afterglows of off-axis merger-induced gamma-ray bursts (GRBs).

Methods. By modelling well-sampled broadband afterglows of 13 merger-induced GRBs, we make predictions for their X-ray light curve behaviour had they been observed off-axis, considering both a uniform jet with core angle θC and a Gaussian-structured jet whose edge lies at an angle θW = 2θC. We compare their peak X-ray luminosity, duration, and temporal indices α (where F ∝ tα) with those of the currently known extragalactic FXTs.

Results. Our analysis reveals that a slightly off-axis observing angle of θobs ≈ (2.2 − 3)θC and a structured jet are required to explain the shallow (|α|≲0.3) temporal indices of the FXT light curves, which cannot be reproduced in the uniform-jet case at any viewing angle. In the case of a structured jet with truncation angle θW = 2θC, the distributions of the duration of the FXTs are consistent with those of the off-axis afterglows for the same range of observing angles, θobs ≈ (2.2 − 3)θC. While the distributions of the off-axis peak X-ray luminosity are consistent only for θobs = 2.2θC, focussing on individual events with different intrinsic luminosities reveals that the match of all three properties (peak X-ray luminosity, duration and temporal indices) of the FXTs at the same viewing angle is possible in the range θobs ∼ (2.2 − 2.6)θC. Despite the small sample of GRBs analysed, these results show that there is a region of the parameter space – although quite limited – where the observational properties of off-axis GRB afterglow can be consistent with those of the newly discovered FXTs. Future observations of FXTs discovered by the recently launched Einstein Probe mission and GRB population studies combined with more complex afterglow models will shed light on this possible GRB-FXT connection, and eventually unveil the progenitors of some FXTs.
Grids of stellar models with rotation
Authors: Sibony Yves , Shepherd Kendall G. , Yusof Norhasliza , Hirschi Raphael , Chambers Caitlan , Tsiatsiou Sophie , Nandal Devesh , Sciarini Luca , Moyano Facundo D. , Bétrisey Jérôme , Buldgen Gaël , Georgy Cyril , Ekström Sylvia , Eggenberger Patrick , Meynet Georges
Published: July 2024

Context. Grids of stellar evolution models with rotation using the Geneva stellar evolution code (GENEC) have been published for a wide range of metallicities.

Aims. We introduce the last remaining grid of GENEC models, with a metallicity of Z = 10−5. We study the impact of this extremely metal-poor initial composition on various aspects of stellar evolution, and compare it to the results from previous grids at other metallicities. We provide electronic tables that can be used to interpolate between stellar evolution tracks and for population synthesis.

Methods. Using the same physics as in the previous papers of this series, we computed a grid of stellar evolution models with GENEC spanning masses between 1.7 and 500 M⊙, with and without rotation, at a metallicity of Z = 10−5.

Results. Due to the extremely low metallicity of the models, mass-loss processes are negligible for all except the most massive stars. For most properties (such as evolutionary tracks in the Hertzsprung-Russell diagram, lifetimes, and final fates), the present models fit neatly between those previously computed at surrounding metallicities. However, specific to this metallicity is the very large production of primary nitrogen in moderately rotating stars, which is linked to the interplay between the hydrogen- and helium-burning regions.

Conclusions. The stars in the present grid are interesting candidates as sources of nitrogen-enrichment in the early Universe. Indeed, they may have formed very early on from material previously enriched by the massive short-lived Population III stars, and as such constitute a very important piece in the puzzle that is the history of the Universe.
Redshift-dependent galaxy formation efficiency at z = 5 − 13 in the FirstLight Simulations
Authors: Ceverino D. , Nakazato Y. , Yoshida N. , Klessen R. S. , Glover S. C. O.
Published: July 2024

Context. Some models of the formation of first galaxies predict low masses and faint objects at extremely high redshifts, z ≃ 9 − 15. However, the first observations of this epoch indicate a higher-than-expected number of bright (sometimes massive) galaxies.

Aims. Numerical simulations can help to elucidate the mild evolution of the bright end of the UV luminosity function and they can provide the link between the evolution of bright galaxies and variations of the galaxy formation efficiency across different redshifts.

Methods. We use the FirstLight database of 377 zoom-in cosmological simulations of a volume- and mass-complete sample of galaxies. Mock luminosities are estimated by a dust model constrained by observations of the β–MUV relation at z = 6 − 9.

Results. FirstLight contains a high number of bright galaxies, MUV ≤ −20, consistent with current data at z = 6 − 13. The evolution of the UV cosmic density is driven by the evolution of the galaxy efficiency and the relation between MUV and halo mass. The efficiency of galaxy formation increases significantly with mass and redshift. At a fixed mass, galactic halos at extremely high redshifts convert gas into stars at a higher rate than at lower redshifts. The high gas densities in these galaxies enable high efficiencies. Our simulations predict higher number densities of massive galaxies, M* ≃ 109 M⊙, than other models with constant efficiency.

Conclusions. Cosmological simulations of galaxy formation with detailed models of star formation and feedback can reproduce the different regimes of galaxy formation across cosmic history.
Geminga’s pulsar halo: An X-ray view
Authors: Manconi Silvia , Woo Jooyun , Shang Ruo-Yu , Krivonos Roman , Tang Claudia , Di Mauro Mattia , Donato Fiorenza , Mori Kaya , Hailey Charles J.
Published: July 2024

Geminga is the first pulsar around which a remarkable gamma-ray halo extending over a few degrees was discovered at TeV energies by MILAGRO and HAWC and later by H.E.S.S., and by Fermi-LAT in the GeV band. More middle-aged pulsars have exhibited gamma-ray halos, and they are now recognised as an emerging class of Galactic gamma-ray sources. The emission appears in the late evolution stage of pulsars, and is most plausibly explained by inverse Compton scattering of CMB and interstellar photons by relativistic electrons and positrons escaping from the pulsar wind nebulae. These observations pose a number of theoretical challenges, particularly the origin of the inferred, significantly lower effective diffusion coefficients around the pulsar when compared to typical Galactic values. Tackling these questions requires constraining the ambient magnetic field properties, which can be achieved through X-ray observations. If the gamma-ray halos originate from a distribution of highly energetic electrons, synchrotron losses in the ambient magnetic fields of the same particles are expected to produce a diffuse X-ray emission with a similar spatial extension. We present the most comprehensive X-ray study of the Geminga pulsar halo to date, utilising archival data from XMM-Newton and NuSTAR. Our X-ray analysis covers a broad bandwidth (0.5 − 79 keV) and large field of view (θ ∼ 4°) for the first time. This was achieved by accurately measuring the background over the entire field of view, and taking into account both focused and stray-light X-ray photons from the pulsar halo with NuSTAR. We find no significant emission and set robust constraints on the X-ray halo flux. These are translated to stringent constraints on the ambient magnetic field strength and the diffusion coefficient by using a physical model considering particle injection, diffusion, and cooling over the pulsar’s lifetime, which is tuned by fitting multi-wavelength data. Our novel methodology for modelling and searching for synchrotron X-ray halos can be applied to other pulsar halo candidates.
Modeling the Enceladus dust plume based on in situ measurements performed with theCassiniCosmic Dust Analyzer
Authors: Ershova A. , Schmidt J. , Postberg F. , Khawaja N. , Nölle L. , Srama R. , Kempf S. , Southworth B.
Published: July 2024

We analyzed data recorded by the Cosmic Dust Analyzer on board theCassinispacecraft during Enceladus dust plume traversals. Our focus was on profiles of relative abundances of grains of different compositional types derived from mass spectra recorded with the Dust Analyzer subsystem during theCassiniflybys E5 and E17. The E5 profile, corresponding to a steep and fast traversal of the plume, has already been analyzed. In this paper, we included a second profile from the E17 flyby involving a nearly horizontal traversal of the south polar terrain at a significantly lower velocity. Additionally, we incorporated dust detection rates from the High Rate Detector subsystem during flybys E7 and E21. We derived grain size ranges in the different observational data sets and used these data to constrain parameters for a new dust plume model. This model was constructed using a mathematical description of dust ejection implemented in the software package DUDI. Further constraints included published velocities of gas ejection, positions of gas and dust jets, and the mass production rate of the plume. Our model employs two different types of sources: diffuse sources of dust ejected with a lower velocity and jets with a faster and more colimated emission. From our model, we derived dust mass production rates for different compositional grain types, amounting to at least 28 kg s−1. Previously, salt-rich dust was believed to dominate the plume mass based on E5 data alone. The E17 profile shows a dominance of organic-enriched grains over the south polar terrain, a region not well constrained by E5 data. By including both E5 and E17 profiles, we find the salt-rich dust contribution to be at most 1% by mass. This revision also results from an improved understanding of grain masses of various compositional types that implies smaller sizes for salt-rich grains. Our new model can predict grain numbers and masses for future mission detectors during plume traversals.
Skipping a beat: Discovery of persistent quasi-periodic oscillations associated with pulsed fraction drop of the spin signal in M51 ULX-7
Authors: Imbrogno Matteo , Motta Sara Elisa , Amato Roberta , Israel Gian Luca , Rodríguez Castillo Guillermo Andres , Brightman Murray , Casella Piergiorgio , Bachetti Matteo , Fürst Felix , Stella Luigi , Pinto Ciro , Pintore Fabio , Tombesi Francesco , Gúrpide Andrés , Middleton Matthew J. , Salvaggio Chiara , Tiengo Andrea , Belfiore Andrea , De Luca Andrea , Esposito Paolo , Wolter Anna , Earnshaw Hannah P. , Walton Dominic J. , Roberts Timothy P. , Zampieri Luca , Marelli Martino , Salvaterra Ruben
Published: July 2024

Context. The discovery of pulsations in (at least) six ultraluminous X-ray sources (ULXs) has shown that neutron stars can accrete at (highly) super-Eddington rates, challenging the standard accretion theories. M51 ULX-7, with a spin signal of P ≃ 2.8 s, is the pulsating ULX (PULX) with the shortest known orbital period (Porb ≃ 2 d) and has been observed multiple times by XMM-Newton, Chandra, and NuSTAR.

Aims. We report on the timing and spectral analyses of three XMM-Newton observations of M51 ULX-7 performed between the end of 2021 and the beginning of 2022, together with a timing re-analysis of XMM-Newton, Chandra, and NuSTAR archival observations.

Methods. We investigated the spin signal by applying accelerated search techniques and studied the power spectrum through the fast Fourier transform, looking for (a)periodic variability in the source flux. We analysed the energy spectra of the 2021–2022 observations and compared them to the older ones.

Results. We report the discovery of a recurrent, significant (> 3σ) broad complex at mHz frequencies in the power spectra of M51 ULX-7. We did not detect the spin signal, setting a 3σ upper limit on the pulsed fraction of ≲10% for the single observation. The complex is significantly detected also in five Chandra observations performed in 2012.

Conclusions. M51 ULX-7 represents the second PULX for which we have a significant detection of mHz-QPOs at super-Eddington luminosities. These findings suggest that one should avoid using the observed QPO frequency to infer the mass of the accretor in a ULX. The absence of spin pulsations when the broad complex is detected suggests that the mechanism responsible for the aperiodic modulation also dampens the spin signal’s pulsed fraction. If true, this represents an additional obstacle in the detection of new PULXs suggesting an even larger occurrence of PULXs among ULXs.
The ALMA-ALPAKA survey
Authors: Rizzo F. , Bacchini C. , Kohandel M. , Di Mascolo L. , Fraternali F. , Roman-Oliveira F. , Zanella A. , Popping G. , Valentino F. , Magdis G. , Whitaker K.
Published: July 2024

The gas in the interstellar medium (ISM) of galaxies is supersonically turbulent. Measurements of turbulence typically rely on cold gas emission lines for low-z galaxies and warm ionized gas observations for z > 0 galaxies. Studies of warm gas kinematics at z > 0 conclude that the turbulence strongly evolves as a function of redshift, due to the increasing impact of gas accretion and mergers in the early Universe. However, recent findings suggest potential biases in turbulence measurements derived from ionized gas at high-z, impacting our understanding of turbulence origin, ISM physics and disk formation. We investigate the evolution of turbulence using velocity dispersion (σ) measurements from cold gas tracers (i.e., CO, [CI], [CII]). The initial dataset comprises 17 galaxy disks with high data quality from the ALPAKA sample, supplemented with galaxies from the literature, resulting in a sample of 57 galaxy disks spanning the redshift range z = 0 − 5. This extended sample consists of main-sequence and starburst galaxies with stellar masses ≳1010 M⊙. The comparison with current Hα kinematic observations and existing models demonstrates that the velocity dispersion inferred from cold gas tracers differ by a factor of ≈3 from those obtained using emission lines tracing the warm, ionized gas. We show that stellar feedback is the main driver of turbulence measured from cold gas tracers and the physics of turbulence driving does not appear to evolve with time. This is fundamentally different from the conclusions of studies based on warm gas, which had to consider additional turbulence drivers to explain the high values of σ. We present a model predicting the redshift evolution of turbulence in galaxy disks, attributing the increase of σ with redshift to the higher energy injected by supernovae due to the elevated star-formation rate in high-z galaxies. This supernova-driven model suggests that turbulence is lower in galaxies with lower stellar mass compared to those with higher stellar mass. Additionally, it forecasts the evolution of σ in Milky-Way like progenitors.
The Pristine survey
Authors: de La Vernhe Isaure González Rivera , Hill Vanessa , Kordopatis Georges , Gran Felipe , Fernández-Alvar Emma , Ardern-Arentsen Anke , Thomas Guillaume F. , Sestito Federico , Navarrete Camila , Martin Nicolas F. , Starkenburg Else , Viswanathan Akshara , Battaglia Giuseppina , Venn Kim A. , Vitali Sara
Published: July 2024

Context. Metal-poor stars hold key information on the early Milky Way. Through the identification and characterisation of substructures, one can understand internal mechanisms (including merger and accretion events), which are indispensable to reconstruct the formation history of the Galaxy.

Aims. To allow an investigation of a population of very metal-poor stars ([Fe/H] < –1.7) with disc-like orbits (planar and prograde), high angular momenta (Lz/Jtot > 0.5) and rotational velocities (Vϕ > 180 km.s−1) proposed in the literature, we used a sample of ∼3 M giant stars with Gaia DR3 BP/RP information and Pristine-Gaia metallicities down to –4.0 dex that we aimed to decontaminate. To achieve this, we constructed a sample as free as possible from spurious photometric estimates, an issue commonly encountered for high Vϕ metal-poor stars.

Methods. We created a statistically robust sample of ∼36 000 Pristine-Gaia very metal-poor ([Fe/H] < –1.7) giant stars, using APOGEE and LAMOST data (adding GALAH and GSP-spec for verification) to estimate and remove contamination. We investigated the spatial and kinematic properties of the decontaminated sample, making use of Vϕ as well as the action space, which are both powerful tools to disentangle stellar populations.

Results. The global distribution of very metal-poor stars in our sample shows the typical kinematics, orbital properties, and spatial distributions of a halo; however, as in previous works, we found a pronounced asymmetry in the Lz and Vϕ distributions, in favour of prograde stars. We showed that this excess is predominantly due to prograde-planar stars (10% of the very metal-poor population), which can be detected down to [Fe/H] = –2.9 at a 2σ confidence level. This prograde-planar population contains stars with Vϕ > 180 km.s−1 and Zmax < 1.5 kpc. While the overall orbital configurations (Zmax − Rmax or action space distributions) of our sample match that of a halo, the highly prograde and planar subset (2% of the very metal-poor population) also bears characteristics classically associated with a thick disc: (i) a spatial distribution compatible with a short-scaled thick disc, (ii) a Zmax − Rmax distribution similar to the one expected from the thick disc prediction of the Gaia Universe Model Snapshot, and (iii) a challenge to erase its signature assuming a stationary or prograde halo with V¯ϕ∼30−40 km.s−1. Altogether, these results seem to rule out that these highly prograde and planar stars are part of a thin disc population and, instead, support a contribution from a metal-weak thick disc. Higher resolution spectra are needed to fully disentangle the origin(s) of the population.
An investigation into Venusian atmospheric chemistry based on an open-access photochemistry-transport model at 0–112 km
Authors: Dai Longkang , Shao Wencheng , Sheng Zheng
Published: July 2024

Atmospheric chemistry plays a crucial role in the evolution of climate habitability on Venus. It has been widely explored by chemistry-transport models, but some characteristics are still poorly interpreted. This study is devoted to developing an open-access chemistry-transport model spanning both the middle and lower atmospheres of Venus. It provides a scheme for the structure of the chemistry, especially for the sulfur and oxygen, and investigates the influence of the cloud diffusivity and the SO2 dissolution that are adopted in the clouds. The developed model is based on the VULCAN framework and was updated with the state-of-the-art Venusian atmospheric chemistry. It includes vertical eddy diffusion retrieved recently with the Venus Express observations, and it resolves radiative transfer containing gas absorption and scattering, Mie scattering of the cloud droplets, and absorption of the unknown UV absorber. The obtained abundance profiles of SO, SO2, CO, COS, O, O2, O3, HCl, and NO are in overall agreement with the observations. The results show that the increase in cloud diffusivity has slight effects on the chemical structure. The SO2 mainly dissolves in 50–90 km and evaporates below the clouds. The rapid dissolution-release cycle is responsible for the large upward flux of SO2 at 58 km. At around 70 km, SO has a significant peak that is larger than that of previous studies by an order of magnitude, and S and SO2 also show slight increases. They are attributed to the buffering effects of liquid SO2 in the clouds. O2 is significantly eliminated by SO in this layer. We emphasize the superior regulation of the sulfur cycle on O2 at 70 km and its potential contributions to the long-standing problem of the overestimated O2 abundance.
Simulations of cluster ultra-diffuse galaxies in MOND
Authors: Nagesh Srikanth T. , Freundlich Jonathan , Famaey Benoit , Bílek Michal , Candlish Graeme , Ibata Rodrigo , Müller Oliver
Published: July 2024

Ultra-diffuse galaxies (UDGs) in the Coma cluster have velocity dispersion profiles that are in full agreement with the predictions of modified Newtonian dynamics (MOND) in isolation. However, the external field effect (EFE) from the cluster seriously undermines this agreement. It has been suggested that this could be related to the fact that UDGs are out-of-equilibrium objects whose stars have been heated by the cluster tides or that they recently fell onto the cluster on radial orbits; thus, their velocity dispersion may not reflect the EFE at their instantaneous distance from the cluster centre. In this work, we simulated UDGs within the Coma cluster in MOND, using the Phantom of Ramses (POR) code. We show that if UDGs are initially at equilibrium within the cluster, tides are not sufficient to increase their velocity dispersions to values as high as the observed ones. On the other hand, if they are on a first radial infall onto the cluster, they can keep high-velocity dispersions without being destroyed until their first pericentric passage. We conclude that in the context of MOND, and without alterations (e.g. a screening of the EFE in galaxy clusters or much higher baryonic masses than currently estimated), we find that UDGs must be out-of-equilibrium objects on their first infall onto the cluster.
Spectroscopy of eclipsing compact hierarchical triples
Authors: Moharana A. , Hełminiak K. G. , Marcadon F. , Pawar T. , Pawar G. , Konacki M. , Jordán A. , Brahm R. , Espinoza N.
Published: July 2024

Context. Eclipsing compact hierarchical triples (CHTs) are systems in which a tertiary star orbits an eclipsing binary (EB) in an orbit of fewer than 1000 days. In a CHT, all three stars exist in a space that is less than 5 AU in radius. A low-mass CHT is an interesting case through which we can understand the formation of multiple stars and planets at such small scales.

Aims. In this study, we combine spectroscopy and photometry to estimate the orbital, stellar, and atmospheric parameters of stars in a sample of CHTs. Using the complete set of parameters, we aim to constrain the metallicity and age of the systems.

Methods. We used time-series spectroscopy to obtain radial velocities (RVs) and disentangled spectra. Using RV modelling, EB light curve modelling, and spectral analysis, we estimated the metallicities and temperatures. Using isochrone fitting, we constrained the ages of the system. We then combined observations of masses, outer eccentricities (e2), orbital periods, and age estimates of the systems from the literature. We compared the distributions of e2, and the tertiary mass ratio, q3 = M3/(M1 + M2), for three different metallicity ranges and two age ranges.

Results. We have estimated the masses, radii, temperatures, metallicities, and ages of 12 stars in four CHTs. The CHT CD-32 6459 shows signs of von Zeipel-Lidov-Kozai oscillations, while CD-62 1257 can evolve to form a triple common envelope. The rest of the CHTs are old and have an M-dwarf tertiary. We find that the q3 distribution for CHTs with sub-solar metallicity has a uniform distribution but the systems with solar and above-solar metallicity peak between 0.5 and 1. When dividing them according to their ages, we find the q3 of old systems to be around 0.5. The eccentricity, e2, favours a value of around 0.3 irrespective of metallicity or age. The distributions of q3 and e2 resemble the distributions of the mass ratio and eccentricity of close field binaries.
Testing the volume integrals of travel-time sensitivity kernels for flows
Authors: Švanda Michal , Chmúrny Daniel
Published: July 2024

Context. Helioseismic inversions largely rely on sensitivity kernels, in which 3D spatial functions describe how the changes in the solar interior translate into the change in helioseismic observables. These sensitivity kernels in most cases come from the forward modelling that is used in the most advanced solar models.

Aims. We aim to test the sensitivity kernels by comparing their volume integrals with measured values from helioseismic travel times.

Methods. By manipulating the tracking rate, we mimicked the additional zonal velocity in the Dopplergram datacubes. These datacubes were then processed by a standard travel-time measurements pipeline. We investigated the dependence of the east-west travel time averaged over a box around the disc centre on the implanted tracking velocity. The slope of this dependence is directly proportional to the total volume integral of the sensitivity kernel that corresponds to the travel-time geometry that is used.

Results. The agreement between measurements and models for travel times that are computed with a ridge filtering is very good to acceptable. The dependence we sought to determine indeed resembles a linear function, and its slope agrees with the expected volume integral from the forward-modelled sensitivity kernel. The agreement is poorer for the phase-speed filtered datacubes. The disagreement is particularly strong for the slowest phase speeds (filters td1–td4). For the higher phase speeds, our result indicates that the measured kernel integrals are systematically larger than expected from the forward modelling. We admit our testing procedure may not be appropriate for high phase speeds and higher radial modes.
General relativistic effects and the near-infrared variability of Sgr A*
Authors: von Fellenberg S. D. , Witzel G. , Bauboeck M. , Chung H.-H. , Marchili N. , Martinez G. , Sadun-Bordoni M. , Bourdarot G. , Do T. , Drescher A. , Fazio G. , Eisenhauer F. , Genzel R. , Gillessen S. , Hora J. L. , Mang F. , Ott T. , Smith H. A. , Ros E. , Ribeiro D. C. , Widmann F. , Willner S. P. , Anton Zensus J.
Published: July 2024

A systematic study, based on the third-moment structure function, of Sgr A*’s variability finds an exponential rise time, τ1,obs = 14.8−1.5+0.4 minutes, and decay time, τ2,obs = 13.1−1.4+1.3 minutes. This symmetry of the flux-density variability is consistent with earlier work, and we interpret it as being caused by the dominance of Doppler boosting, as opposed to gravitational lensing, in Sgr A*’s light curve. A relativistic, semi-physical model of Sgr A* confirms an inclination angle of i ≲ 45°. The model also shows that the emission of the intrinsic radiative process can have some asymmetry even though the observed emission does not. The third-moment structure function, which is a measure of the skewness of the light-curve increments, may be a useful summary statistic in other contexts of astronomy because it senses only temporal asymmetry; that is, it averages to zero for any temporally symmetric signal.
Dry Weather Adaptations in Wastewater Treatment: Innovative Control Strategies for Effective Organic and Nitrogen Elimination
Authors: Kumar B Santosh , Singh Navdeep , Bharath Bhushan Yannam , Kumar Chandra Pradeep , Addai Ali Hanaa , Singh Shivani , Kumar Shi Ram Shiva
Published: July 2024

Through a meta-heuristic framework, this study examines various wastewater treatment methods in detail and proposes a novel application of genetic algorithms (GAs) in plant optimization. ASM models are adapted to include ion speciation and pairing models, and microplastics (MPs) are challenged, indicating the need for further research. An integrated model accounts for carbon, nitrogen, phosphorus, oxygen, and hydrogen, emphasizing pH’s crucial role in biological treatment processes by examining microbial growth rates and organic compound removal. By applying natural selection and evolutionary processes, GAs are investigated as an optimization tool for plants, improving gene sequence structures and, by extension, treatment processes. The importance of this is particularly evident when dealing with non-standard numerical solutions and algebraic calculations. A robust and adaptable wastewater treatment strategy that accommodates variable weather conditions is provided by the study, which illustrates GAs, their stopping conditions, and the selection process for fitness functions.
Water and Hydrology: Challenges, Sustainable Strategies and Future Trends
Authors: K Aravinda , Sravanthi Jajimoggala , Lakhanpal Sorabh , Shrivastava Anurag , Kalra Ravi , Mohammad Q. , Kumar Mishra Nirmith
Published: July 2024

The paper gives a comprehensive review of how human activities influence normal hydrological forms by clarifying the diverse impacts on the accessibility, quality, and conveyance of water. The paper revealed the complex exchange between data and natural morals that are reconfiguring the worldwide water scene through conflicting facts of major causes like urbanization, deforestation, industrialization, and climate change. The natural areas are all disturbed by human activities and pollution and by these changes the impact is on run-off patterns, infiltration rates, and groundwater recharge processes. In metropolitan cities, there are more impermeable spaces which leads to more runoffs. In these areas, the water filtration rate and groundwater recharge are very low. Dams and other hydropower and water system processes that disturb the natural stream of waterways in addition to their aquatic habitat division have too changed stream morphology. Urban stormwater, industrial and farming runoff, are among numerous other sources contaminate freshwater systems with pathogens heavy metals, chemicals supplements, etc hence risking both human life and natural maintainability. Changes in precipitation and temperature impact the timing of snow melt, patterns of river flow, and restoration of groundwater; changes in disaster patterns together with sea level rise worsen coastal flooding and fresh-water salinization. These adjustments to common hydrologic processes have significant suggestions for biological systems, communities, and economies consisting of water accessibility for farming, industry, and domestic purposes, energy generation, and human well being. Among procedures aimed at reacting to these challenges is the Integrated Water Resource Management (IWRM) which contends for comprehensive approaches that accommodate competing requests over water resources while guaranteeing their supportability as well as adaptability to hydrological unpredictability of availability. Feasible water administration requires an extend of activities such as water preservation and proficiency measures, contamination control, watershed management, and climate alteration adjustment. As it may, social orders can explore these exceedingly complicated interconnected issues on their water assets by adopting administrative systems, innovative advancements, and shifts in social conduct that will be pointed at economical water utilization for the eras to come.
Enhancing Solar PV Performance: Advanced Converters for Efficient Green Energy Conversion and Grid Compatibility
Authors: Vishwakarma Neelesh , Vittalaiah A. , Reddy N.V. Uma , Sobti Rajeev , Kumar Ashwani , Mohammad Q. , Rao A. Shubhangi
Published: July 2024

This paper delves into the vital role of converters in enhancing the efficiency and reliability of solar photovoltaic (PV) systems. With the escalating demand for renewable energy sources, solar PV systems emerge as a sustainable solution, necessitating advanced power electronics for optimal performance. The study highlights various DC-DC converters, such as buck, boost, and buck-boost converters, analyzing their functionalities in achieving maximum power point tracking (MPPT) and their implications on system cost, efficiency, and limitations. Further examination of gridconnected PV systems underscores the necessity for sophisticated inverter designs to ensure high efficiency, minimal harmonic distortion, and effective power management. Through MATLAB SIMULINK simulations, the paper evaluates the performance of solar PV systems equipped with different converter and inverter configurations, addressing the challenges posed by power fluctuations and the integration of solar energy into the grid. The research contributes to the ongoing discourse on renewable energy integration, presenting innovative solutions for grid synchronization, voltage regulation, and harmonic distortion reduction in solar PV systems.
Simultaneous Wireless Power and Data Transfer in Different Applications
Authors: Babu Bobba Phaneendra , Anwar Mohd Hamza , Prasad Bhupathi Hari , Shirisha P. , Hamza Laeth
Published: July 2024

In Modern Era, the demand for wireless technology has surged exponentially, promising enhanced living comfort and safety. Simultaneous Wireless Power and Data Transfer (SWPDT) has emerged as a critical area of study, finding applications in electric vehicles, underwater autonomous vehicles, and biomedical implants. This technology facilitates real-time monitoring while supplying power, eliminating the need for bulky cables and conventional power sources. Hence this paper addresses the state-of-art of SWPDT in different applications This comprehensive review covers various SWPDT implementation methods for applications like electric vehicles, biomedical implants, and autonomous underwater vehicles. Different techniques for implementation of SWPDT using inductive links and its design recommendations.
MOF based membranes in gas separation area
Authors: Chen Zetian
Published: July 2024

Microporous metal organic framework materials are a series of noticeable membrane materials for the separation of gas molecules and liquid molecules. MOFs can be functionalized through tuning pore size through the variation of ligand length, metal nodes and more, or through adjusting adsorption site such as functional sites, linker functional sites, and open metal sites. Membranes can provide higher structure stability for MOFs, however, addressing synthetic, processing, and design challenges is crucial to produce MOF films with excellent mechanical integrity, chemical stability, and high performance under relevant industrial conditions，such as interfacial compatibility issues towards Mixed-Matrix-Membranes (MMMs) and Pure-MOF film issues regarding chemical and thermal robustness, morphology, and orientation. The alkyne/alkene separation, alkane/alkene separation and more gas mixture has been proven can be achieved through the use of MOF-based membranes, moreover, compared to traditional methods, MOF-based membranes possess better performance on separating forementioned gas mixtures with higher selectivity, purity and less harm to the environment.
Achieving Electric Aviation with Advanced Battery Technology and Nanomaterials
Authors: Wang Lixin
Published: July 2024

With the continuous development of industry, environmental problems continue to worsen, of which the environmental problems caused by the traditional aviation industry are particularly serious, but there are many problems with electric aircraft that have not been solved. Therefore, this paper explores the realization of electric aviation by using advanced battery technology and nanomaterials. The study found that there are a variety of advanced battery technologies and nanomaterials that contribute to the realization of electric aviation, among which Multi-walled carbon nanotubes(MWCNT)/ graphene-based composite phase change material technology has considerable potential. It has excellent battery thermal management performance and excellent high-power density. However, MWCNT/ graphene-based composite phase change material technology also has shortcomings at present, such as the production process is complex and difficult to mass produce. Although there are still many challenges, this paper believes that these challenges will be solved to enable electric aviation using advanced battery technology and nanomaterials.
Application of carbon nanotubes in lithium-ion batteries
Authors: Gao Chenghong
Published: July 2024

Battery demand as a power source has skyrocketed due to the electric car market’s explosive growth. Because of its high energy density, lack of memory effect, low self-discharge rate, environmental friendliness, and extended cycle life, lithium-ion batteries, or LIBs, are widely employed in electric cars, aircraft, and other sectors. However, the use of traditional carbon materials in LIBs has led to relatively low specific capacity, limited charging and discharging rates, and low first-time charging and discharging efficiencies Carbon nanotubes (CNTs), with their high electrical conductivity, excellent mechanical properties, and thermal conductivity, can bring higher capacity, better cycling stability, excellent thermal conductivity, as well as lightweight and flexibilization to LIBs. Therefore, this paper first introduces the basic properties of CNTs and their preparation methods. Then, their roles in the positive and negative electrodes of LIBs are discussed respectively. Finally, an outlook on the future development of LIBs is made. This has a reference value for the future development of LIBs.
Photoelectric sensors constructed based on nanomaterials and their applications
Authors: Wu Weijie
Published: July 2024

Photoelectric sensors are electronic components that use the photoelectric effect to convert optical signals into electrical signals and are widely used in industrial automation, environmental monitoring, medical devices, and other fields. With continuous progress in fields such as information technology, material science, and manufacturing technology, optoelectronic sensor technology has developed rapidly. Nanomaterials have broad application prospects in optoelectronic sensors due to their unique properties. On the one hand, nanomaterials can enhance the electromagnetic field of light, leading to charge separation and enhanced electron transport, thereby achieving higher photoelectric conversion efficiency. On the other hand, nanomaterials have a larger specific surface area and higher light absorption and photosensitivity. In addition, due to the small size of nanomaterials, their surface energy has a greater impact and their response to the environment is more sensitive. This makes optoelectronic sensors based on nanomaterials a current research hotspot. Therefore, this article mainly introduces photoelectric sensors constructed using nanomaterials and their applications. This article first introduces various optoelectronic sensors made of nanomaterials, including inorganic semiconductors, organic photovoltaic materials, and two-dimensional materials. In addition, its applications in food safety, environmental monitoring, and medical fields were emphasized. It has reference significance for the development of future photoelectric sensors.