bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photodissociation and induced chemical asymmetries on ultra-hot gas giants
Authors: Baeyens Robin , Désert Jean-Michel , Petrignani Annemieke , Carone Ludmila , Schneider Aaron David 
Published: March 2024

Context. Recent observations have resulted in the detection of chemical gradients on ultra-hot gas giants. Notwithstanding their high temperature, chemical reactions in ultra-hot atmospheres may occur in disequilibrium, due to vigorous day-night circulation and intense UV radiation from their stellar hosts.
Aims. The goal of this work is to explore whether photochemistry is affecting the composition of ultra-hot giant planets, and if it can introduce horizontal chemical gradients. In particular, we focus on hydrogen cyanide (HCN) on WASP-76 b, as it is a photochemically active molecule with a reported detection on only one side of this planet.
Methods. We used a pseudo-2D chemical kinetics code to model the chemical composition of WASP-76 b along its equator. Our approach improved on chemical equilibrium models by computing vertical mixing, horizontal advection, and photochemistry.
Results. We find that the production of HCN is initiated through the thermal and photochemical dissociation of CO and N2 on the day side of WASP-76 b. The resulting radicals are subsequently transported to the night side via the equatorial jet stream, where they recombine into different molecules. This process results in an HCN gradient with a maximal abundance on the planet’s morning limb. We verified that photochemical dissociation is a necessary condition for this mechanism, as thermal dissociation alone proves insufficient. Other species produced via night-side disequilibrium chemistry are SO2 and S2.
Conclusions. Our model acts as a proof of concept for chemical gradients on ultra-hot exoplanets. We demonstrate that even ultra-hot planets can exhibit disequilibrium chemistry and recommend that future studies do not neglect photochemistry in their analyses of ultra-hot planets.
Long-term monitoring of large-scale magnetic fields across optical and near-infrared domains with ESPaDOnS, Narval, and SPIRou
Authors: Bellotti S. , Morin J. , Lehmann L. T. , Petit P. , Hussain G. A. J. , Donati J.-F. , Folsom C. P. , Carmona A. , Martioli E. , Klein B. , Fouqué P. , Moutou C. , Alencar S. , Artigau E. , Boisse I. , Bouchy F. , Bouvier J. , Cook N. J. , Delfosse X. , Doyon R. , Hébrard G. 
Published: March 2024

Context. Dynamo models describing the generation of stellar magnetic fields for partly and fully convective stars are guided by observational constraints. Zeeman-Doppler imaging has revealed a variety of magnetic field geometries and, for fully convective stars in particular, a dichotomy: either strong, mostly axisymmetric, and dipole-dominated or weak, non-axisymmetric, and multipole-dominated. This dichotomy is explained either by dynamo bistability (i.e., two coexisting and stable dynamo branches) or by long-term magnetic cycles with polarity reversals, but there is no definite conclusion on the matter.
Aims. Our aim is to monitor the evolution of the large-scale field for a sample of nearby M dwarfs with masses between 0.1 and 0.6 M⊙, which is of prime interest to inform distinct dynamo theories and explain the variety of magnetic field geometries studied in previous works. This also has the potential to put long-term cyclic variations of the Sun’s magnetic field into a broader context.
Methods. We analysed optical spectropolarimetric data sets collected with ESPaDOnS and Narval between 2005 and 2016, and near-infrared SPIRou data obtained between 2019 and 2022 for three well-studied, active M dwarfs: EV Lac, DS Leo, and CN Leo. We looked for secular changes in time series of longitudinal magnetic field, width of unpolarised mean-line profiles, and large-scale field topology as retrieved with principal component analysis and Zeeman-Doppler imaging.
Results. We retrieved pulsating (EV Lac), stable (DS Leo), and sine-like (CN Leo) long-term trends in longitudinal field. The width of near-infrared mean-line profiles exhibits rotational modulation only for DS Leo, whereas in the optical it is evident for both EV Lac and DS Leo. The line width variations are not necessarily correlated to those of the longitudinal field, suggesting complex relations between small- and large-scale field. We also recorded topological changes in the form of a reduced axisymmetry for EV Lac and transition from a toroidal-dominated to poloidal-dominated regime for DS Leo. For CN Leo, the topology remained predominantly poloidal, dipolar, and axisymmetric, with only an oscillation in field strength.
Conclusions. Our results show a peculiar evolution of the magnetic field for each M dwarf individually, with DS Leo and EV Lac manifesting more evident variations than CN Leo. These findings confirm that M dwarfs with distinct masses and rotation periods can undergo magnetic long-term variations and suggest an underlying variety of cyclic behaviours of their magnetic fields.
Modeling the effects of starspots on stellar magnetic cycles
Authors: Zhang Zebin , Jiang Jie , Kitchatinov Leonid 
Published: March 2024

Context. Observations show that faster rotating stars tend to have stronger magnetic activity and shorter magnetic cycles. The cyclical magnetic activity of the Sun and stars is believed to be driven by the dynamo process. The success of the Babcock-Leighton (BL) dynamo in explaining the solar cycle suggests that starspots could play an important role in stellar magnetic cycles.
Aims. We aim to extend the BL mechanism to solar-mass stars with various rotation rates and explore the effects of emergence properties of starspots in latitudes and tilt angles on stellar magnetic cycles.
Methods. We adopt a kinematic BL-type dynamo model operating in the bulk of the convection zone. The profiles of the large-scale flow fields are from the mean-field hydrodynamical model for various rotators. The BL source term in the model is constructed based on the rotation dependence of starspot emergence; that is, faster rotators have starspots at higher latitudes with larger tilt angles.
Results. Faster rotators have poloidal flux appearing closer to about ±55° latitudes, where the toroidal field generation efficiency is the strongest because of the peak in the strength of the latitudinal differential rotation there. It takes a shorter time for faster rotators to transport the surface poloidal field from their emergence latitude to the ±55° latitudes of efficient Ω-effect, which shortens their magnetic cycles. The faster rotators operate in a more supercritical regime because of a stronger BL α-effect relating to the tilt angles, which leads to stronger saturated magnetic fields and makes the coupling of the poloidal field between two hemispheres more difficult. The magnetic field parity therefore shifts from the hemispherically asymmetric mixed mode to quadrupole, and further to dipole when a star spins down.
Conclusions. The emergence of starspots plays an essential role in the large-scale stellar dynamo.
CON-quest
Authors: Nishimura Y. , Aalto S. , Gorski M. D. , König S. , Onishi K. , Wethers C. , Yang C. , Barcos-Muñoz L. , Combes F. , Díaz-Santos T. , Gallagher J. S. , García-Burillo S. , González-Alfonso E. , Greve T. R. , Harada N. , Henkel C. , Imanishi M. , Kohno K. , Linden S. T. , Mangum J. G. , Martín S. , Muller S. , Privon G. C. , Ricci C. , Stanley F. , van der Werf P. P. , Viti S. 
Published: March 2024

Context. Nuclear regions of ultraluminous and luminous infrared galaxies (U/LIRGs) are powered by starbursts and/or active galactic nuclei (AGNs). These regions are often obscured by extremely high columns of gas and dust. Molecular lines in the submillimeter windows have the potential to determine the physical conditions of these compact obscured nuclei (CONs).
Aims. We aim to reveal the distributions of HCN and HCO+ emission in local U/LIRGs and investigate whether and how they are related to galaxy properties.
Methods. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we have conducted sensitive observations of the HCN J = 3−2 and HCO+J = 3−2 lines toward 23 U/LIRGs in the local Universe (z < 0.07) with a spatial resolution of ∼0.3″ (∼50−400 pc).
Results. We detected both HCN and HCO+ in 21 galaxies, only HCN in one galaxy, and neither in one galaxy. The global HCN/HCO+ line ratios, averaged over scales of ∼0.5−4 kpc, range from 0.4 to 2.3, with an unweighted mean of 1.1. These line ratios appear to have no systematic trend with bolometric AGN luminosity or star formation rate. The line ratio varies with position and velocity within each galaxy, with an average interquartile range of 0.38 on a spaxel-by-spaxel basis. In eight out of ten galaxies known to have outflows and/or inflows, we found spatially and kinematically symmetric structures of high line ratios. These structures appear as a collimated bicone in two galaxies and as a thin spherical shell in six galaxies.
Conclusions. Non-LTE analysis suggests that the high HCN/HCO+ line ratio in outflows is predominantly influenced by the abundance ratio. Chemical model calculations indicate that the enhancement of HCN abundance in outflows is likely due to high-temperature chemistry triggered by shock heating. These results imply that the HCN/HCO+ line ratio can aid in identifying the outflow geometry when the shock velocity of the outflows is sufficiently high to heat the gas.
Impact of aeolian erosion on dust evolution in protoplanetary discs
Authors: Michoulier Stéphane , Gonzalez Jean-François , Grishin Evgeni , Petetin Clement 
Published: March 2024

Context. Many barriers prevent dust from forming planetesimals via coagulation in protoplanetary discs, such as bouncing, collisional fragmentation, or aeolian erosion. Modelling dust and the different phenomena that can alter its evolution is therefore necessary. Multiple solutions have been proposed, but they still need to be confirmed.
Aims. In this paper, we explore the role that aeolian erosion plays in the evolution of dust.
Methods. We used a mono-disperse model to account for dust growth and fragmentation, implemented in a 1D code to compute the evolution of single grains and in a 3D smoothed particle hydrodynamics (SPH) code to compute the global evolution of dust and gas. We tested the erosion model in our code and ensured it matched previous results.
Results. With a disc model that reproduces observations, we show with both 1D and 3D studies that erosion is not significant during the evolution of dust when we take fragmentation into consideration. With a low-viscosity disc, fragmentation is less of a problem, but grain growth is also less important, which prevents the formation of large objects. In dust traps, close to the star, erosion is also not impactful, even when fragmentation is turned off.
Conclusions. We show in this paper that aeolian erosion is negligible when radial drift, fragmentation, and dust traps are taken into account and that it does not alter the dust evolution in the disc. However, it can have an impact on later stages, when the streaming instability forms large clumps close to the star, or when planetesimals are captured.
Breaking the baryon-dark matter degeneracy in a model-independent way through the Sunyaev-Zeldovich effect
Authors: Alfano Anna Chiara , Luongo Orlando , Muccino Marco 
Published: March 2024

Context.In cosmological fits, it is common to fix the baryon densityωbvia the cosmic microwave background. We here constrainωbby means of a model-independent interpolation of the acoustic parameter from correlated baryonic acoustic oscillations.Aims.The proposed technique is used to alleviate the degeneracy between baryonic and dark matter abundances.Methods.We propose a model-independent Bézier parametric interpolation and applied it to intermediate-redshift data. We first interpolated the observational Hubble data to extract cosmic bounds over the (reduced) Hubble constanth0and interpolated the angular diameter distances,D(z), of the galaxy clusters, inferred from the Sunyaev-Zeldovich effect, to constrain the spatial curvature, Ωk. Through the Hubble points andD(z) determined in this way, we interpolated uncorrelated data of baryonic acoustic oscillations bounding the baryonωband total matterωmdensities, reinforcing the constraints onh0and Ωkwith the same technique. Finally, to remove the matter sector degeneracy, we obtainedωbby interpolating the acoustic parameter from correlated baryonic acoustic oscillations.Results.Monte Carlo Markov chain simulations agree at 1σconfidence level with the flat ΛCDM model and are roughly suitable at 1σwith its nonflat extension, while the Hubble constant appears in tension up to the 2σconfidence levels.Conclusions.Our method excludes very small extensions of the standard cosmological model, and on the Hubble tension side, seems to match local constraints slightly.
The interplay between forming planets and photoevaporating discs
Authors: Weber M. L. , Picogna G. , Ercolano B. 
Published: March 2024

Context. Disc winds and planet–disc interactions are two crucial mechanisms that define the structure, evolution, and dispersal of protoplanetary discs. While winds are capable of removing material from discs, eventually leading to their dispersal, massive planets can shape their disc by creating sub-structures such as gaps and spiral arms.
Aims. We studied the interplay between an X-ray photoevaporative disc wind and the sub-structures generated due to planet–disc interactions to determine how their mutual interactions affect the disc’s and the planet’s evolution.
Methods. We performed 3D hydrodynamic simulations of viscous discs (α = 6.9 × 10−4) that host a Jupiter-like planet and undergo X-ray photoevaporation. We traced the gas flows within the disc and wind and measured the rate of accretion onto the planet, as well as the gravitational torque that is acting on it.
Results. Our results show that the planetary gap removes the wind’s pressure support, allowing wind material to fall back into the gap. This opens new pathways for material from the inner disc (and part of the outer disc) to be redistributed through the wind towards the gap. Consequently, the gap becomes shallower and the flow of mass across the gap in both directions is significantly increased, as is the planet’s mass-accretion rate (by factors of ≈5 and ≈2, respectively). Moreover, the wind-driven redistribution results in a denser inner disc and a less dense outer disc, which, combined with the recycling of a significant portion of the inner wind, leads to longer lifetimes for the inner disc, contrary to the expectation in a planet-induced photoevaporation scenario that has been proposed in the past.
Galaxies in the zone of avoidance: Misclassifications using machine learning tools
Authors: Marchant Cortés P. , Nilo Castellón J. L. , Alonso M. V. , Baravalle L. , Villalon C. , Sgró M. A. , Daza-Perilla I. V. , Soto M. , Milla Castro F. , Minniti D. , Masetti N. , Valotto C. , Lares M. 
Published: March 2024

Context. Automated methods for classifying extragalactic objects in large surveys offer significant advantages compared to manual approaches in terms of efficiency and consistency. However, the existence of the Galactic disk raises additional concerns. These regions are known for high levels of interstellar extinction, star crowding, and limited data sets and studies.
Aims. In this study, we explore the identification and classification of galaxies in the zone of avoidance (ZoA). In particular, we compare our results in the near-infrared (NIR) with X-ray data.
Methods. We analyzed the appearance of objects in the Galactic disk classified as galaxies using a published machine-learning (ML) algorithm and make a comparison with the visually confirmed galaxies from the VVV NIRGC catalog.
Results. Our analysis, which includes the visual inspection of all sources cataloged as galaxies throughout the Galactic disk using ML techniques reveals significant differences. Only four galaxies were found in both the NIR and X-ray data sets. Several specific regions of interest within the ZoA exhibit a high probability of being galaxies in X-ray data but closely resemble extended Galactic objects. Our results indicate the difficulty in using ML methods for galaxy classification in the ZoA, which is mainly due to the scarcity of information on galaxies behind the Galactic plane in the training set. They also highlight the importance of considering specific factors that are present to improve the reliability and accuracy of future studies in this challenging region.
Ponderomotive forces in magnetized nonthermal space plasmas due to cyclotron waves
Authors: Espinoza-Troni Joaquín , Asenjo Felipe A. , Moya Pablo S. 
Published: March 2024

Context. The ponderomotive force is involved in a variety of space plasma phenomena characterized by the family of Kappa distributions. Therefore, evaluating these nonthermal effects in the ponderomotive force is required.
Aims. The Karpman–Washimi ponderomotive interaction due to cyclotron waves is evaluated for different space conditions considering low-temperature magnetized plasmas described by an isotropic Kappa distribution and with a wave propagation parallel to the background magnetic field.
Methods. We performed a brief analysis of the influence of the Kappa distribution in the dispersion relation for a low-temperature plasma expansion at the lowest order in which the thermal effects can be appreciated without considering the damping characteristics of the wave. The different factors of the ponderomotive force were obtained and analyzed separately as a function of the wavenumber, the spectral index κ, and the plasma beta.
Results. We found a relevant influence of the nonthermal effects in all factors of the ponderomotive force for magnetized plasmas. The effect of the Kappa distribution has been evaluated for a wide variety of space environments, such as the solar wind and the different regions of our magnetosphere, where it has been found that these results can be relevant for the solar wind, the magnetosheath, the plasma sheet, and the polar cusps. We also analyzed the role of the nonthermal effect in the induced Karpman–Washimi ponderomotive magnetization in the context of spatial plasmas and the total radiated power associated with it.
Conclusions. We find that even for nearly cold magnetized plasmas and waves far from the resonances, the effect of the kappa parameter in the ponderomotive force cannot be neglected. This suggests a significant role of the Kappa distribution in ponderomotive phenomena of space physics.
The physical properties of T Pyx as measured by MUSE
Authors: Izzo L. , Pasquini L. , Aydi E. , Della Valle M. , Gilmozzi R. , Harvey E. A. , Molaro P. , Otulakowska-Hypka M. , Selvelli P. , Thöne C. C. , Williams R. 
Published: March 2024

Context. T Pyx is one of the most enigmatic recurrent novae, and it has been proposed as a potential Galactic type-Ia supernova progenitor.
Aims. Using spatially resolved data obtained with MUSE, we characterized the geometrical distribution of the material expelled in previous outbursts surrounding the white dwarf progenitor.
Methods. We used a 3D model for the ejecta to determine the geometric distribution of the extended remnant. We also calculated the nebular parallax distance (d = 3.55 ± 0.77 kpc) based on the measured velocity and spatial shift of the 2011 bipolar ejecta. Our findings confirm previous results, including the data from the Gaia mission.
Results. The remnant of T Pyx can be described by a two-component model consisting of a tilted ring at i = 63.7 relative to its normal vector and fast bipolar ejecta perpendicular to the plane of the equatorial ring.
Conclusions. We found an upper limit for the bipolar outflow ejected mass in 2011 of the bipolar outflow of Mej, b < (3.0 ± 1.0)×10−6 M⊙, which is lower than previous estimates given in the literature. However, only a detailed physical study of the equatorial component can provide an accurate estimate of the total ejecta of the last outburst, a fundamental step to understanding if T Pyx will end its life as a type-Ia supernova.
Giant radio galaxies in the LOFAR deep fields
Authors: Simonte M. , Andernach H. , Brüggen M. , Miley G. K. , Barthel P. 
Published: March 2024

Context. The reason why some radio galaxies (RGs) grow to form so-called giant radio galaxies (GRGs) with sizes > 700 kpc, is still unknown.
Aims. In this study, we compare the radio, optical and environmental properties of GRGs with those of a control sample of smaller RGs we found in the three LOw-Frequency ARray (LOFAR) deep fields, namely the Boötes, ELAIS-N1, Lockman Hole, for a total area of ≈95 deg2.
Methods. We inspected the LOFAR deep fields and created a catalogue of 1609 extended radio galaxies (ERGs). By visual inspection, we identified their host galaxies and spectroscopically or photometrically classified 280 of these as GRGs. We studied their properties, such as their accretion state, stellar mass and star formation rate (SFR) using deep optical and infrared survey data. Moreover, we explored the environment in terms of the surface number density of neighbouring galaxies within these surveys. Integrated flux densities and radio luminosities were also determined for a subset of ERGs through available survey images at 50, 150, 610, and 1400 MHz to compute integrated spectral indices.
Results. Considering the fraction of GRGs displaying an FRII morphology alongside the host galaxy properties, we suggest that GRGs consistently possess sufficient power to overcome jet frustration caused by the interstellar medium. Moreover, clear differences emerge in the environmental densities between GRGs and smaller RGs, using the number of neighbouring galaxies within 10 Mpc from the host galaxy as a proxy. GRGs preferentially reside in sparser environments compared to their smaller counterparts. In particular, only 3.6% of the GRGs reside within a 3D comoving distance of 5 Mpc from a previously reported galaxy cluster. We found that larger sources exhibit steeper integrated spectral indices, suggesting that GRGs are late-stage versions of RGs. These results suggest that GRGs are amongst the oldest radio sources with the most stable nuclear activity that reside in sparse environments.