Konkoly Observatory

Quartz is a ubiquitous, durable mineral abundant in most lithologies and in sedimentary systems. Its stability during weathering and diagenesis makes it a robust provenance tracer. Quartz optically stimulated luminescence (OSL) sensitivity and electron spin resonance (ESR) signals have been empirically proposed as indicators for sediment provenance based on differences in quartz sensitivity. Sensitivity is defined as luminescence produced per unit dose (Gray: Gy) per unit mass (mg). The mechanisms driving OSL sensitisation during weathering from source rocks remain an open question in the luminescence community. While it is largely believed to be acquired by earth surface processes, recent studies bring evidence that sensitisation processes depend on source geology. Moreover, most studies focus on quartz grains deposited in the sink and infer possible sources rock by clustering.The present study investigated a diverse suite of source rocks a wide range of geological settings, including granites, sandstones, volcanic and metamorphic rocks, and, where applicable, their derived sediments, independently dated from millions (Ma) to billions (Ga) of years. To understand the mechanism of OSL sensitivity we combined thermoluminescence (TL), OSL, ESR, cathodoluminescence (CL) and Raman spectroscopy measurements, with geochemical data obtained through laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Only in those quartzes that exhibited the [TiO4-Li+]0 paramagnetic centre in ESR, had notably high concentration of titanium and lithium impurities and had high blue emission in SEM-CL showed sensitisation following repeated cycles of laboratory dosing and bleaching. Samples lacking these centres did not show any laboratory OSL sensitisation by dosing and bleaching. We find a strong correlation of the degree of laboratory OSL sensitisation with the [TiO4-Li+]0 electron centre from ESR signal, and the titanium and lithium concentrations measured by LA-ICPMS. Our data on rocks of various ages and regions reinforce the idea that the potential for OSL sensitisation originates from specific lattice defect structures acquired by quartz during crystallisation. The results also highlight the role of Li⁺-ion impurities in forming paramagnetic centres such as [AlO₄/h]0 and [TiO4-Li+]0, advancing our understanding on interaction of radiations with specific defects in quartz.This study is funded by the European Research Council Consolidator Grant - PROGRESS, (ERC-CoG-101043356) awarded to Prof. Alida Timar-Gabor.

The use of white-rot fungi Pleurotus spp. and Trametes versicolor in continuous-flow fixed-bed systems has emerged as a promising and sustainable approach for the removal of different pollutants from aqueous media. This overview presents the most important design and operating parameters, the efficiency of fixed-bed systems using these fungi and their spent substrate, and the effect of operating parameters on changes in removal efficiency. After a literature screening based on the Scopus database, the overview focuses specifically on 55 studies that present the results of several hundred tests, meeting the criteria for continuous-flow fixed-bed systems, which include ensuring uninterrupted flow, constant adsorbent mass, and continuous interaction between the stationary and mobile phases. Results reported in the literature show the varying importance of biodegradation and biosorption processes in the removal of metals and organic pollutants (e.g., dyes, pharmaceuticals, pesticides, volatile compounds). The overview highlights the impact of operational parameters on removal efficiency, including bed depth, flow rate, type of polluted water, and initial concentration. It also determines that these fixed-bed systems using Pleurotus spp. and Trametes versicolor are primarily suitable for modelling the adsorption-based removal of given pollutants and the bioremediation of smaller amounts of municipal, industrial, or agricultural wastewater.

Many studies in the past few decades have investigated the evolution of young stellar objects based on their spectral energy distribution. This distribution is heavily affected not only by the evolutionary stage, but also by the morphology of the forming star. This study is part of the NEMESIS project, which aims to revisit star formation with the aid of machine-learning techniques and provides the framework for this work. In a first effort toward a novel spectro-morphological classification, we analyzed the morphologies of young stellar objects and linked them to the currently used observational classes. Thereby, we laid the foundation for a spectro-morphological classification and applied the insights learned in this study in a future revisited classification scheme. We obtained archival high-resolution survey images from VISTA for approximately (10,000) young stellar object candidates from the literature toward the Orion star formation complex. Using a self-organizing map algorithm, which is an unsupervised machine-learning method, we created a grid of morphological prototypes from near- and mid-infrared images. Furthermore, we determined the prototypes that best represent the different observational classes we derived from the infrared spectral index via Bayesian inference. We present our grids of morphological prototypes of young stellar objects in the near-infrared. The prototypes were created from observational data alone. They are thus independent of theoretical models. In addition, we show maps that indicate the probability for a prototype to belong to any of the observational classes. Self-organizing maps created from near-infrared images are a useful tool, with limitations, for identifying the characteristic morphologies of young stellar objects in different evolutionary stages. This first step lays the foundation for a spectro-morphological classification of young stellar objects that is to be developed in the future.

Abstract O–C shell mergers in massive stars are a site for producing the p- nuclei by the γ process, but 1D stellar models rely on mixing length theory (MLT), which does not match the radial velocity profiles of 3D hydrodynamic simulations. We investigate how 3D macrophysics-informed mixing impacts the nucleosynthesis of p- nuclei. We postprocess the O shell of the M ZAMS = 15 M ⊙ , Z = 0.02 model from the NuGrid stellar data set. Applying a downturn to velocities at the boundary and increasing velocities across the shell as obtained in previous results, we find a nonlinear, nonmonotonic increase in p -nuclei production with a spread of 0.96 dex and find that isotopic ratios can change. Reducing C-shell ingestion rates as found in 3D simulations suppresses production, with spreads of 1.22–1.84 dex across MLT and downturn scenarios. Applying dips to the diffusion profile to mimic quenching events also suppresses production, with a 0.51 dex spread. We analyze the impact of varying all photodisintegration rates of unstable n -deficient isotopes from Se to Po by a factor of 10 up and down. The nuclear physics variations for the MLT and downturn cases have a spread of 0.56–0.78 dex. We also provide which reaction rates are correlated with the p- nuclei and find few correlations shared between mixing scenarios. Our results demonstrate that uncertainties in mixing arising from uncertain 3D macrophysics are as significant as nuclear physics and are crucial for understanding p -nuclei production during O–C shell mergers quantitatively.

<strong class="journal-contentHeaderColor">Abstract.</strong> Stable isotopes of hydrogen and oxygen in precipitation (<em>&delta;ₚ</em>) are important natural tracers in wide range of environmental applications (e.g., the exploration of the water cycle, ecology and food authenticity), yet observational records commonly contain gaps, although applications in hydrology and earth science frequently require complete cases. Eight imputation approaches were benchmarked using monthly <em>&delta;ₚ</em> time series from Austria, Slovenia, and Hungary. Uninterrupted periods were selected, and monthly data were masked site-wise with an increasing degree of missingness, removing 1 to 32 % of the data using bootstrapping. The imputation performance of the following methods was assessed on the masked monthly data using the mean absolute difference and root mean square error between the observed and imputed values for primary and secondary isotopic parameters: Last Observation Carried Forward, Linear Interpolation, Spline Interpolation, Stineman Interpolation, Kalman Smoothing, Moving Average Imputation, Sinusoidal fit, and a spatial proximity-based imputation (SPbI) approach introduced in the present paper. SPbI estimates missing &delta;ₚ values using the mean of altitude-corrected &delta;ₚ data from within a predefined search radius. Across masking levels, SPbI was the most accurate and least prone to amplitude damping in <em>&delta;ₚ</em> records. Sinusoidal imputation remained robust under increasing missingness but has shown a tendency of reducing extremes, indicating amplitude loss in both <em>&delta;ₚ</em> and d-excess. Spline performed worst overall with the rest performing similarly up to ~16 % masking beyond which their performance deteriorated. A sensitivity analysis using non-cumulative 50-km distance bands up to 400 km showed that SPbI errors increase with distance; beyond ~250 km, mean errors approach those of the sinusoidal method, making the sinusoidal&mdash;or even the simpler linear interpolation&mdash;a viable alternative when proximal observations are sparse. The benchmarking results recommend the use of SPbI where station data are available within 250 km distance, and the sinusoidal or linear approach otherwise.

We present half-light radius measurements for the dwarf satellites of Andromeda, based on multi-epoch imaging from the Isaac Newton Telescope (INT) Monitoring Survey of Local Group dwarf galaxies. This analysis is conducted within a larger study to identify long-period variable (LPV) stars in these galaxies. The survey was performed with the Wide Field Camera on the 2.5-m INT and covers multiple epochs obtained between 2015 and 2018 in the i (Sloan) and V (Harris) bands. To determine the half-light radii, we derived surface brightness and number density profiles for each system and fitted them with Exponential, Plummer, and S´ersic models. The resulting half-light radii are in good agreement with literature values but reveal subtle variations linked to differences in stellar distribution and morphology. Distances were independently estimated using the Tip of the Red Giant Branch (TRGB) method, yielding values consistent with previous determinations. The complete photometric and variability catalogs will be made publicly available through CDS/VizieR, providing a valuable resource and foundation for future studies of the structure, stellar populations, and evolution of Andromeda’s dwarf companions.

Abstract Several short-lived radionuclides (SLRs) are know to have existed in the early solar system (ESS). These species, which typically decay with half-lives of the order of a few million years, can be used to probe the timescales of events preceding the birth of the Sun. We investigate the ESS origin of 53 Mn, produced by core-collapse supernovae (CCSNe) and Type Ia supernovae (SNe Ia), and 60 Fe, produced exclusively by CCSNe. We model the evolution of the radioactive-to-stable abundance ratios of these SLRs with a Galactic chemical evolution (GCE) framework accounting for different SN yields, SN Ia delay times, and other Galactic features ( K ). A further set of models is calculated assuming that SNe Ia did not contribute any 53 Mn to the ESS. The predicted ratios are compared to meteoritic ratios to derive a distribution of solar isolation times that includes uncertainties due to stochastic chemical enrichment and measurements of the ESS values. The isolation times are then compared to those of 107 Pd and 182 Hf calculated in previous work. A self-consistent solution can be found within the current uncertainties, especially when using the GCE setups with K = 1.6 and 2.3, although the maximum likelihood for the 60 Fe distribution is typically ∼4–5 Myr shorter than for 53 Mn. The predicted 60 Fe/ 53 Mn ratio, instead, is completely inconsistent with the ESS value; this could be resolved using a larger fraction of faint CCSNe than usually considered in GCE models.

High-energy irradiation in X-rays and UV (XUV) can transform the planetary atmospheres through photoevaporation and photochemistry. This is more crucial for M stars, whose habitable zones for Earth-like planets are located within a few percent of an AU. Transiting exoplanets around M dwarfs offer the opportunity to study their characteristics and habitability conditions. L 98-59 is an M3 dwarf hosting six Earth-like planets, with two of them in the habitable zone of the star. X-ray observations made in 2020 and 2021 detected significant flares above a quiescent luminosity of 4-10 x 10^26 erg/s. We present the results from two short XMM-Newton observations of L 98-59, which are part of a monitoring survey to detect long-term X-ray variability and activity cycles. In October 2024 the X-ray quiescent luminosity of the star was about 5.9 x 10^25 erg/s, and it was about 6.3 x 10^26 erg/s in February 2025. We speculate that in late 2024 the star had a minimum of activity; in 2021 the star was near a maximum of an activity cycle, and in 2025 it was at the middle of the cycle. We suggest a coarse estimate of the period of about 2 years and a peak-to-peak amplitude of about 10, which is the highest among the stars with a known X-ray cycle other than the Sun. We also infer that even the outer planet in the habitable zone, L 98-59f, is exposed to an X-ray dose between 100 and 1600 times the X-ray irradiation of the Earth in the XMM band.

Compact symmetric objects (CSOs) trace the earliest phases of radio-galaxy growth; however, robust classification is difficult when radio cores are weak or invisible. We aim to develop and test a Gaia +VLBI approach that utilizes the high-precision optical astrometry of Gaia together with the high-resolution imaging of very long baseline interferometry (VLBI) to reliably locate the central engine and classify CSOs. We analysed 40 literature CSO candidates by overlaying Gaia Data Release 3 (DR3) positions on VLBI maps and by examining spectral index distributions, whole-source variability, and hotspot kinematics over up to 25 years. A source is classified as a CSO when the Gaia centroid lies between two steep-spectrum lobes; alignment with one end of the radio structure indicates a core--jet source. Our method yields 20 confirmed CSOs, ten core--jet sources, and ten ambiguous cases affected by significant optical--radio positional offsets or limited data. The confirmed CSOs show low integrated variability, hotspot advance speeds typically $&lt;0.5 , c$, where c denotes the speed of light (with a few mildly relativistic cases), and kinematic ages of ≈ 20-2000 yr. Five nearby CSOs show systematic Gaia --VLBI offsets despite the CSO-like morphology, likely reflecting host-galaxy environments and Gaia astrometric systematics. We find a clear dichotomy with radio power: high-power CSOs (P_ GHz W Hz ) tend to be larger and host faster hotspots, while many low-power systems remain sub‑kiloparsec and environmentally confined. Gaia +VLBI registration is a powerful method for CSO classification, especially where radio cores are faint. The observed power-size-velocity-age relations support distinct multiple evolutionary tracks, with high-power CSOs plausibly growing into large radio galaxies, while low-power CSOs appear confined by their host galaxy environments. Taken together, our results indicate that CSO evolution is shaped not only by intrinsic jet power, but also by host--galaxy environment and the duty cycle of the central engine. High-sensitivity observations of low-power CSOs will be crucial to map the full diversity of formation channels and evolutionary pathways of radio galaxies.