Star clusters were historically considered simple stellar populations, with all stars sharing the same age and initial chemical composition. However, the presence of chemical anomalies in globular clusters (GCs), called multiple stellar populations (MPs), has challenged star formation theories in dense environments. Literature studies show that mass, metallicity, and age are likely controlling parameters for the manifestation of MPs. Identifying the limit between clusters with/without MPs in physical parameter space is crucial to reveal the driving mechanism behind their presence. In this study, we look for MP signals in Whiting 1, traditionally considered a young GC. Using the Magellan telescope, we obtained low-resolution spectra within $\rm \lambda\lambda = 3850-5500 Å$ for eight giants of Whiting 1. We measured the C and N abundances from the CN and CH spectral indices. C and N abundances have variations comparable with their measurement errors ($\sim0.1$ dex), suggesting that MPs are absent from Whiting 1. Combining these findings with literature studies, we propose a limit in the metallicity vs. cluster compactness index parameter space, which relatively clearly separates star clusters with/without MPs (GCs/open clusters). This limit is physically motivated. On a larger scale, the galactic environment determines cluster compactness and metallicity, leading to metal-rich, diffuse, old clusters formed ex situ. Our proposed limit also impacts our understanding of the formation of the Sagittarius dwarf galaxy: star clusters formed after the first starburst (age$\lesssim 8-10$ Gyr). These clusters are simple stellar populations because the enriched galactic environment is no longer suitable for MP formation.

Recent DESI DR2 observations indicate that dark energy has crossed from phantom to quintessence regime, a behavior known as the quintom-B realization. In this work we constrain dynamical dark energy and modified gravity using the swampland Trans-Planckian Censorship Conjecture (TCC), which forbids eternal acceleration since in this case any trans-Planckian quantum fluctuation would eventually stretch beyond the Hubble radius, breaking the applicability of any effective field theory and cosmological techniques. By combining DESI DR2 data with the TCC criterion, we impose tight constraints on the dark energy equation of state and its parameter space in scenarios such as the Chevallier-Polarski-Linder, Barboza-Alcaniz, Jassal-Bagla-Padmanabhan, EXP and LOG parameterizations, significantly constraining the quintom-A behavior. Also we examine models within the framework of $f(T)$ and $f(Q)$ modified gravity theories, demonstrating that TCC is very powerful to constrain or exclude them, a result that indicates the necessity to consider infrared modifications on General Relativity apart from the usual ultraviolet ones. Our findings imply that viable dynamical dark energy scenarios must asymptotically transit to deceleration, shedding light on new physics consistent with both cosmological observations and quantum gravity principles.

The distribution of close-in exoplanets is shaped by the interplay between atmospheric and dynamical processes. The Neptunian Desert, Ridge, and Savanna illustrate the sensitivity of these worlds to such processes, making them ideal to disentangle their roles. Determining how many Neptunes were brought close-in by early disk-driven migration (DDM; maintaining primordial spin-orbit alignment) or late high-eccentricity migration (HEM; generating large misalignments) is essential to understand how much atmosphere they lost. We propose a unified view of the Neptunian landscape to guide its exploration, speculating that the Ridge is a hot spot for evolutionary processes. Low-density Neptunes would mainly undergo DDM, getting fully eroded at shorter periods than the Ridge, while denser Neptunes would be brought to the Ridge and Desert by HEM. We embark on this exploration via ATREIDES, which relies on spectroscopy and photometry of 60 close-in Neptunes, their reduction with robust pipelines, and their interpretation through internal structure, atmospheric, and evolutionary models. We carried out a systematic RM census with VLT/ESPRESSO to measure the distribution of 3D spin-orbit angles, correlate its shape with system properties and thus relate the fraction of aligned-misaligned systems to DDM, HEM, and atmospheric erosion. Our first target, TOI-421c, lies in the Savanna with a neighboring sub-Neptune TOI-421b. We measured their 3D spin-orbit angles (Psib = 57+11-15 deg; Psic = 44.9+4.4-4.1 deg). Together with the eccentricity and possibly large mutual inclination of their orbits, this hints at a chaotic dynamical origin that could result from DDM followed by HEM. ATREIDES will provide the community with a wealth of constraints for formation and evolution models. We welcome collaborations that will contribute to pushing our understanding of the Neptunian landscape forward.

Traditional information retrieval is primarily concerned with finding relevant information from large datasets without imposing a structure within the retrieved pieces of data. However, structuring information in the form of narratives--ordered sets of documents that form coherent storylines--allows us to identify, interpret, and share insights about the connections and relationships between the ideas presented in the data. Despite their significance, current approaches for algorithmically extracting storylines from data are scarce, with existing methods primarily relying on intricate word-based heuristics and auxiliary document structures. Moreover, many of these methods are difficult to scale to large datasets and general contexts, as they are designed to extract storylines for narrow tasks. In this paper, we propose Narrative Trails, an efficient, general-purpose method for extracting coherent storylines in large text corpora. Specifically, our method uses the semantic-level information embedded in the latent space of deep learning models to build a sparse coherence graph and extract narratives that maximize the minimum coherence of the storylines. By quantitatively evaluating our proposed methods on two distinct narrative extraction tasks, we show the generalizability and scalability of Narrative Trails in multiple contexts while also simplifying the extraction pipeline.

The canonical formation of second-generation (G2) stars in globular clusters (GCs) from gas enriched and ejected by G1 (primordial) polluters faces substantial challenges, i.e. (i) a mass-budget problem and (ii) uncertainty in the source(s) of the abundance anomaly of light elements (AALE) in G2 stars. The merger of G1 low-mass main-sequence (MS) binaries can overcome (i), but its ability to result in AALE is omitted. We provide evidence of the merger process to explain AALE by relying on highly probable merger remnants in the Galactic disk. We focus on carbon-deficient red-clump giants with low mass of 1.0 M_{\sun} < M $\lesssim$ 2.0 M_{\sun} and hot He-intermediate subdwarfs of supersolar metallicity, both manifesting G2-like AALE incompatible with GC origin. The origin of such rare core He-burning stars as the mergers of [MS star (MSS)]+[helium white dwarf (HeWD)] binaries, evolved from low-mass high-mass ratio (MSS+MSS) ones, is supported by models evolving to either horizontal branch (HB) stars or He subdwarfs via the red giant branch (RGB). Such binaries in the GC NGC 362 contain very young ($\sim$ 4 Myr) extremely low-mass HeWDs, in contrast to much older ($\sim 100$ times) counterparts in open clusters. This agrees with the impact of GC environment on the lifetime of hard binaries: (MSS+HeWD) systems merge there soon after arising from (MSS+MSS) binaries that underwent the common-envelope stage of evolution. From the number and lifetime of the (MSS+HeWD) binaries uncovered in NGC 362, the expected fraction of their progeny RGB G2 stars is estimated to be $\lesssim$10\%. The field merger remnants with G2-like AALE support the merger nature of at least a fraction of G2 stars in GCs. The specific channel [(MSS+MSS) - (MSS+HeWD) - merger product] supported by observations and models is tentatively identified as the channel of formation of the extreme G2 RGB component in GCs.

We investigate entanglement islands and the Page curve in the framework of Horndeski gravity on a Karch-Randall braneworld background. In particular, treating the holographic boundary conformal field theory analytically we find that the Horndeski parameters significantly alter the behavior of the Page curve compared to standard general relativity, a feature caused by the nontrivial geometry induced by the Horndeski scalar field. Interestingly enough, the geometry far from the AdS limit plays a more significant role compared to previous studies. This suggests that Horndeski gravity introduces important modifications to the distribution of quantum information in the holographic model. Finally, we claim that holographic consistency can be used reversely to impose constraints on Horndeski gravity itself, providing a new tool for probing the validity of modified gravity theories.

We investigate FLRW cosmology in the framework of symmetric teleparallel $f(Q)$ gravity with a nonminimal coupling between dark matter and the gravitational field. In the noncoincidence gauge, the field equations admit an equivalent multi-scalar field representation, which we investigate the phase-space using the Hubble-normalization approach. We classify all stationary points for arbitrary function $f(Q)$ and we discuss the physical properties of the asymptotic solutions. For the power-law theory, we perform a detailed stability analysis and show that the de Sitter solution is the unique future attractor, while the matter-dominated point appears as a saddle point. Moreover, there exist a family of scaling solutions that can be related to inflationary dynamics. In contrast with uncoupled $f(Q)$ models, the presence of the coupling introduces a viable matter-dominated era alongside late-time accelerated expansion. Our study shows that the coupling function plays a crucial role in cosmological dynamics in $f(Q)$ gravity.

As part of the KESPRINT collaboration, we present the discovery and characterization of three exoplanets in the sub-Neptune to super-Neptune regime, spanning key regions of the exo-Neptunian landscape. TOI-1472c and TOI-1648b are newly discovered sub-Neptunes, while TOI-1472b is a previously known super-Neptune for which we provide an improved mass measurement. These planets have orbital periods of 6--15 days and radii of 2.5--4.1 R$_\oplus$, probing regions where planet formation and atmospheric evolution remain poorly understood. We combine TESS transit photometry with ground-based radial velocities to determine precise masses, radii, and orbital properties. TOI-1472b has a mass of $18.0^{+0.84}_{-0.85}$ M$_\oplus$ and a radius of $4.06 \pm 0.10$ R$_\oplus$, TOI-1472c has a mass of $21.1^{+0.96}_{-0.99}$ M$_\oplus$ and a radius of $3.33 \pm 0.08$ R$_\oplus$, and TOI-1648b has a mass of $7.4^{+1.1}_{-1.3}$ M$_\oplus$ and a radius of $2.54^{+0.14}_{-0.12}$ R$_\oplus$. The planets exhibit a range of eccentricities (0.041--0.178), indicating diverse evolutionary histories. TOI-1648b, with a high Transmission Spectroscopy Metric (TSM $\sim$59), is a promising target for atmospheric characterization. Together, these three planets provide precise constraints on the structure, composition, and dynamical evolution of small to intermediate-sized exoplanets, enriching our understanding of the exo-Neptunian landscape.

Liller 1 is a stellar system orbiting within the inner 0.8kpc of the Galactic centre, characterised by a wide spread in age and metallicity, indicating a high mass. Liller 1 has been proposed to be a major contributor to the stellar mass of the Galactic bulge, yet its origin is subject to debate. We employ Sloan Digital Sky Survey IV (SDSS-IV) data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) to test scenarios proposed to explain the nature of Liller 1. Using a random sampling technique, we contrast the chemical compositions of Liller 1 stellar members with those of the bulge, inner disc, outer disk and solar neighbourhood. The chemistry of Liller 1 deviates from that of the bulge population at the 2-3$\sigma$ level for $\alpha$-elements Mg, Si, and Ca. We conclude that the progenitor of Liller 1 was not a major contributor of stellar mass to the bulge. Furthermore, we find the abundance pattern of Liller 1 to deviate at the 2$\sigma$ level from that of inner disk stars, ruling out the cluster rejuvenation scenario. Finally, we find that Liller 1 is chemically distinct from solar and outer disc populations, suggesting that the progenitor of Liller 1 is unlikely to be an in-situ massive clump formed at high redshift, from disc gravitational instabilities, that migrated inwards and coalesced with others into the bulge. Finally, we suggest that Liller 1 is a minor contributor to the stellar mass of the inner Galaxy, possibly of extragalactic origin.

We present the discovery and characterization of two warm mini-Neptunes transiting the K3V star TOI-815 in a K-M binary system. Analysis of the spectra and rotation period reveal it to be a young star with an age of $200^{+400}_{-200}$Myr. TOI-815b has a 11.2-day period and a radius of 2.94$\pm$0.05$\it{R_{\rm\mathrm{\oplus}}}$ with transits observed by TESS, CHEOPS, ASTEP, and LCOGT. The outer planet, TOI-815c, has a radius of 2.62$\pm$0.10$\it{R_{\rm\mathrm{\oplus}}}$, based on observations of three non-consecutive transits with TESS, while targeted CHEOPS photometry and radial velocity follow-up with ESPRESSO were required to confirm the 35-day period. ESPRESSO confirmed the planetary nature of both planets and measured masses of 7.6$\pm$1.5 $\it{M_{\rm \mathrm{\oplus}}}$ ($\rho_\mathrm{P}$=1.64$^{+0.33}_{-0.31}$gcm$^{-3}$) and 23.5$\pm$2.4$\it{M_{\rm\mathrm{\oplus}}}$ ($\rho_\mathrm{P}$=7.2$^{+1.1}_{-1.0}$gcm$^{-3}$) respectively. Thus, the planets have very different masses, unlike the usual similarity of masses in compact multi-planet systems. Moreover, our statistical analysis of mini-Neptunes orbiting FGK stars suggests that weakly irradiated planets tend to have higher bulk densities compared to those suffering strong irradiation. This could be ascribed to their cooler atmospheres, which are more compressed and denser. Internal structure modeling of TOI-815b suggests it likely has a H-He atmosphere constituting a few percent of the total planet mass, or higher if the planet is assumed to have no water. In contrast, the measured mass and radius of TOI-815c can be explained without invoking any atmosphere, challenging planetary formation theories. Finally, we infer from our measurements that the star is viewed close to pole-on, which implies a spin-orbit misalignment at the 3$\sigma$ level.

In the last few decades planet search surveys have been focusing on solar type stars, and only recently the high-mass regimes. This is mostly due to challenges arising from the lack of instrumental precision, and more importantly, the inherent active nature of fast rotating massive stars. Here we report NGTS-33b (TOI-6442b), a super-Jupiter planet with mass, radius and orbital period of 3.6 $\pm$ 0.3 M$_{\rm jup}$, 1.64 $\pm$ 0.07 R$_{\rm jup}$ and $2.827972 \pm 0.000001$ days, respectively. The host is a fast rotating ($0.6654 \pm 0.0006$ day) and hot (T$_{\rm eff}$ = 7437 $\pm$ 72 K) A9V type star, with a mass and radius of 1.60 $\pm$ 0.11 M$_{\odot}$ and 1.47 $\pm$ 0.06 R$_{\odot}$, respectively. Planet structure and Gyrochronology models shows that NGTS-33 is also very young with age limits of 10-50 Myr. In addition, membership analysis points towards the star being part of the Vela OB2 association, which has an age of $\sim$ 20-35 Myr, thus providing further evidences about the young nature of NGTS-33. Its low bulk density of 0.19$\pm$0.03 g cm$^{-3}$ is 13$\%$ smaller than expected when compared to transiting hot Jupiters with similar masses. Such cannot be solely explained by its age, where an up to 15$\%$ inflated atmosphere is expected from planet structure models. Finally, we found that its emission spectroscopy metric is similar to JWST community targets, making the planet an interesting target for atmospheric follow-up. Therefore, NGTS-33b's discovery will not only add to the scarce population of young, massive and hot Jupiters, but will also help place further strong constraints on current formation and evolution models for such planetary systems.

We present a first large-scale kinematic map of $\sim$50,000 young OB stars ($T_{\rm eff} \geq 10,000$ K), based on BOSS spectroscopy from the Milky Way Mapper OB program in the ongoing Sloan Digital Sky Survey V (SDSS-V). Using photogeometric distances, line-of-sight velocities and Gaia DR3 proper motions, we map 3D Galactocentric velocities across the Galactic plane to $\sim$5 kpc from the Sun, with a focus on radial motions ($v_R$). Our results reveal mean radial motion with amplitudes of $\pm 30$ km/s that are coherent on kiloparsec scales, alternating between inward and outward motions. These $\bar{v}_R$ amplitudes are considerably higher than those observed for older, red giant populations. These kinematic patterns show only a weak correlation with spiral arm over-densities. Age estimates, derived from MIST isochrones, indicate that 85% of the sample is younger than $\sim300$ Myr and that the youngest stars ($\le 30$ Myr) align well with density enhancements. The age-dependent $\bar{v}_R$ in Auriga makes it plausible that younger stars exhibits different velocity variations than older giants. The origin of the radial velocity features remains uncertain, and may result from a combination of factors, including spiral arm dynamics, the Galactic bar, resonant interactions, or phase mixing following a perturbation. The present analysis is based on approximately one-third of the full target sample. The completed survey will enable a more comprehensive investigation of these features and a detailed dynamical interpretation.

The Rosette Nebula is a well-known H II region shaped by the interaction of gas with the OB stars of the NGC 2244 stellar association. Located within the remnant of a giant molecular cloud, it exhibits a complex structure of ionized gas, molecular material, dust, and embedded clusters. In October 2023, the region was observed as part of the SDSS-V Local Volume Mapper (LVM) integral field spectroscopy survey. Covering a radius of approximately 1 degree, the dataset comprises 33,326 spectra with spatially resolved information spanning 390 - 980 nm. We present a structural analysis of the ionized, molecular, and dusty components using multi-wavelength observations: optical spectroscopy from SDSS-V LVM, 12CO emission from PMO/MWISP (sub-millimeter), and dust emission from WISE (12 micron) and Herschel (far-infrared). These datasets were complemented with the positions of ionizing stars to study emission structures traced by H alpha, H beta, [O III], [N II], and [S II], as well as the spatial distribution of line ratios (H alpha/H beta, [O III]/H beta, [N II]/H alpha, and [S II]/H alpha) relative to the surrounding molecular cloud. Our analysis reveals interaction zones between ionized and neutral gas, including filaments, globules, and dense regions with or without ongoing star formation. Radial and quadrant-based flux profiles further highlight morphological and ionization variations, supporting the scenario in which the Rosette Nebula evolved from a non-homogeneous molecular cloud with a thin, sheet-like structure.

This work investigates the connection between quantum complexity and gravitational dynamics within the framework of Horndeski gravity, extending the AdS/BCFT correspondence to include scalar-tensor interactions. By refining the ``$complexity = action$'' conjecture we investigate how Horndeski gravity modifies the Wheeler-DeWitt patch and the causal structure of the black hole. Our analysis reveals that the linear growth of complexity, proportional to the product of black hole entropy and temperature, remains valid across various black hole configurations, including those of rotating and charged black holes. Moreover we study the impact of shock waves on the growth of complexity, which shows the appearance of the ``switchback effect''. These results show the universality of the complexity = action conjecture and its validity in modified gravitational theories.

As narrative extraction systems grow in complexity, establishing user trust through interpretable and explainable outputs becomes increasingly critical. This paper presents an evaluation of an Explainable Artificial Intelligence (XAI) system for narrative map extraction that provides meaningful explanations across multiple levels of abstraction. Our system integrates explanations based on topical clusters for low-level document relationships, connection explanations for event relationships, and high-level structure explanations for overall narrative patterns. In particular, we evaluate the XAI system through a user study involving 10 participants that examined narratives from the 2021 Cuban protests. The analysis of results demonstrates that participants using the explanations made the users trust in the system's decisions, with connection explanations and important event detection proving particularly effective at building user confidence. Survey responses indicate that the multi-level explanation approach helped users develop appropriate trust in the system's narrative extraction capabilities. This work advances the state-of-the-art in explainable narrative extraction while providing practical insights for developing reliable narrative extraction systems that support effective human-AI collaboration.

A crucial requirement for machine learning algorithms is not only to perform well, but also to show robustness and adaptability when encountering novel scenarios. One way to achieve these characteristics is to endow the deep learning models with the ability to detect out-of-distribution (OOD) data, i.e. data that belong to distributions different from the one used during their training. It is even a more complicated situation, when these data usually are multi-label. In this paper, we propose an approach based on evidential deep learning in order to meet these challenges applied to visual recognition problems. More concretely, we designed a CNN architecture that uses a Beta Evidential Neural Network to compute both the likelihood and the predictive uncertainty of the samples. Based on these results, we propose afterwards two new uncertainty-based scores for OOD data detection: (i) OOD - score Max, based on the maximum evidence; and (ii) OOD score - Sum, which considers the evidence from all outputs. Extensive experiments have been carried out to validate the proposed approach using three widely-used datasets: PASCAL-VOC, MS-COCO and NUS-WIDE, demonstrating its outperformance over several State-of-the-Art methods.

We present the first detailed chemical analysis from APOGEE-2S observations of stars in six regions of recently discovered substructures in the outskirts of the Magellanic Clouds extending to 20 degrees from the LMC center. We also present, for the first time, the metallicity and alpha-abundance radial gradients of the LMC and SMC out to 11 degrees and 6 degrees, respectively. Our chemical tagging includes 13 species including light, alpha, and Fe-peak elements. We find that the abundances of all of these chemical elements in stars populating two regions in the northern periphery - along the northern "stream"-like feature - show good agreement with the chemical patterns of the LMC, and thus likely have an LMC origin. For substructures located in the southern periphery of the LMC, we find more complex chemical and kinematical signatures, indicative of a mix of LMC-like and SMC-like populations. However, the southern region closest to the LMC shows better agreement with the LMC, whereas that closest to the SMC shows a much better agreement with the SMC chemical pattern. When combining this information with 3-D kinematical information for these stars, we conclude that the southern region closest to the LMC has likely an LMC origin, whereas that closest to the SMC has an SMC origin, and the other two southern regions have a mix of LMC and SMC origins. Our results add to the evidence that the southern substructures of the LMC periphery are the product of close interactions between the LMC and SMC, and thus likely hold important clues that can constrain models of their detailed dynamical histories.

Below about 2.3 $\mu$m, the nighttime emission of the Earth's atmosphere is dominated by non-thermal radiation from the mesosphere and thermosphere. As this airglow can even outshine scattered moonlight in the near-infrared regime, the understanding of the Earth's night-sky brightness requires good knowledge of the complex airglow emission spectrum and its variability. As airglow modelling is very challenging, the comprehensive characterisation of airglow emission requires large data sets of empirical data. For fixed locations, this can be best achieved by archived spectra of large astronomical telescopes with a wide wavelength coverage, high spectral resolving power, and good temporal sampling. Using 10 years of data from the X-shooter echelle spectrograph in the wavelength range from 0.3 to 2.5 $\mu$m and additional data from the Ultraviolet and Visual Echelle Spectrograph at the Very Large Telescope at Cerro Paranal in Chile, we have succeeded to build a comprehensive spectroscopic airglow model for this low-latitude site under consideration of theoretical data from the HITRAN database for molecules and from different sources for atoms. The Paranal Airglow Line And Continuum Emission (PALACE) model comprises 9 chemical species, 26,541 emission lines, and 3 unresolved continuum components. Moreover, there are climatologies of relative intensity, solar cycle effect, and residual variability with respect to local time and day of year for 23 variability classes. Spectra can be calculated with a stand-alone code for different conditions, also including optional atmospheric absorption and scattering. In comparison to the observed X-shooter spectra, PALACE shows convincing agreement and is significantly better than the previous, widely used airglow model for Cerro Paranal.

The dSphs around the Milky Way are commonly considered as systems that are supported by velocity dispersion against self-gravitation. They have been long accounted among the best targets to search for indirect DM signatures in the GeV-to-TeV gamma-rays due to absence of astrophysical gamma-ray foreground or background emission. We present forecasts on the sensitivity of the future CTAO for the search for annihilating or decaying DM in such targets. We perform an original selection of candidates out of the current catalog of known objects, including both classical and ultra-faint targets. For each of them, we calculate the expected amount of DM using the most updated and complete available samples of photometric and spectroscopic data of member stars, adopting a common framework of data treatment for both classes of objects. In this way, we are able to generate novel astrophysical factor profiles for general indirect DM searches that we compare with the current literature. Out of a starting sample of 64 dSphs, we highlight the 8 most promising targets - DraI, CBe, UMaII, UMi and Wil1 in the Northern hemisphere; RetII, Scl and SgrII in the Southern hemisphere - for which different DM density models (either cored or cuspy) lead to similar expectations, at variance with what happens for other DM targets - thus resulting in more robust predictions. We find that CTAO will provide the strongest limits above ~10 TeV, down to values of velocity-averaged annihilation cross section of ~5$\times 10^{-25}$ cm$^3$ s$^{-1}$ and up to decay lifetimes of ~10$^{26}$ s for combined limits on the best targets. We argue that the largest source of inaccuracy is due to the still imprecise determination of the DM content, especially for ultra-faint dSphs. We propose possible strategies of observation for CTAO, either optimized on a deep focus on the best known candidates, or on the diversification of targets.