We present a collection of eclipse timings of eclipsing binary stars obtained over the extended time interval 2014-2024. In all observations, a DSLR camera was used as the detector. The presented dataset contains 250 previously unpublished minima of 86 eclipsing binary systems obtained at three observing sites. The minima were determined from calibrated light curves using the phenomenological modelling approach, and their uncertainties were estimated by bootstrap resampling. The presented measurements extend the available timing coverage of the observed systems and may contribute to future studies of orbital period variations and other long-term phenomena in eclipsing binaries.
We revisit three published high-velocity-star catalogues drawn from Gaia and LAMOST-Li et al. (2021, 591 stars), Li et al. (2023, 88 stars) and Liao et al. (2024, 519 stars)-and quantify how the published unbound classification of these candidates changes with the choice of distance estimator and with the choice of radial-velocity catalogue. After Gaia DR3 source id resolution and de-duplication our master sample contains 1101 unique stars. 675 of them satisfy ruwe < 1.4, Pi/sigma(Pi) > 5 and carry a Gaia DR3 radial velocity (the Gaia-only clean sample). 356 additionally pass a 1 arcsec LAMOST DR9 LRS cross-match, atmospheric-parameter cuts and a 50 km s(-1) Gaia-LAMOST RV agreement test (the final-strict sample). For every star in this strict subset, the three-dimensional Galactocentric rest-frame speed v (grf) and the local escape speed v(esc) are computed with a 1000-draw Monte Carlo under the MWPoTENTiAL2014 potential of Bovy (2015), once with inverse-parallax distances (1000/Pi ) and once with the geometric distances of Bailer-Jones et al. (2021). Switching from inverse parallax to Bailer-Jones distances on the same 356 stars reduces the count with P (unbound)=P ( v(grf) > v(esc) ) > 0.5 from 48 to 3, and the count with P unbound > 0.9 from 12 to 1 ; 45 stars are downgraded across the P-unbound=0.5 threshold and none are gained. Substituting LAMOST radial velocities for Gaia radial velocities on the same subset changes the median v(grf) by 0.00 km s(-1) ( p(90) Delta v(grf)=5.7 km s(-1) ) and flips the P-unbound=0.5 classification of one star out of 356. The unbound classification of these published candidates is therefore set by the distance estimator, not by the choice of radial-velocity catalogue. The final-strict sample, a Top-15 main candidate table, and a Top-30 machine-readable supplementary CSV are released with this paper; the three highest-confidence candidates are metal-poor giants that warrant targeted spectroscopic follow-up.
In this study, we present a comprehensive photometric and physical characterization of the main-belt asteroid (300) Geraldina. Our analysis includes determining its sidereal rotational period, shape modeling, spin-axis orientation, as well as dynamical and spectral properties. The investigation is based on two decades of archival photometry from the Bulgarian National Astronomical Observatory (BNAO) Rozhen, complemented by dense CCD lightcurve observations obtained since 2017 at the Astronomical Station Vidojevica (ASV), dense data from ALCDEF, and augmented with sparse-in-time measurements from Gaia Data Release 3 (DR3). By combining these heterogeneous datasets within and using the lightcurve inversion method, we confirmed the asteroid's prograde sense of rotation and obtained two symmetrically mirrored pole solutions for the asteroid model. Our dynamical studies show that (300) Geraldina remains stable in 100 Myr. Although close to the 2:1 mean-motion resonance with Jupiter, it is not captured into it during the observed time. Instead, it exhibits interactions with an unidentified high-order mean-motion resonance, which appears to contribute to its long-term stability. Its spectral type (C) with a primitive carbonaceous composition, in combination with low albedo and long-term stability, is consistent with the assumption that (300) Geraldina is an ancient asteroid.
This study explores photometric variability in a sample of hot stars in order to test whether variability arises from rotational modulation due to surface temperature spots. Frequencies determined from the projected rotational velocities were compared with frequencies estimated on the basis of TESS light curves. In all five cases, the spectroscopic frequency was lower than the photometric one preserving possibility that the observed brightness variations can be rotationally induced. In two of our targets, HT Cet and HD 219487, the phoOur results suggest that spot activity inducing rotational modulation may exist in stars hotter than 6500 K, highlighting the value of combined spectroscopic and photometric analysis of variations.
In this research, we conducted a search for new variable stars among recent Transiting Exoplanet Survey Satellite observations. We have chosen data from the 79th sector and a part of the 77th sector. As the main result, we discovered 191 variable stars with a sufficient signal-to-noise ratio that were not classified as variables before. We classified 43 of them and determined the variability period for 89 objects. In addition, we found an object with highly unusual changes in magnitude (TIC 149623590), for which we encourage further investigation. The objective of this project is to attract new citizen scientists to astronomy by conducting simple research under the supervision of more experienced mentors.
The effects of hyperon interactions (occurring through the coupling of hyperons to the sigma & lowast; and phi mesons) on the surface gravitational redshift z of proto-neutron stars (PNSs)-specifically PSR J0740+6620, PSR J0348+0432, PSR J1614-2230, and PSR J0737-3039A-are investigated using relativistic mean field theory. It is found that the increase in central pressure and central energy density due to hyperon interactions becomes more pronounced for higher-mass PNSs, while for lower-mass PNSs this effect is negligible. When hyperon interactions are included, the mass M, compactness M/R, and surface gravitational redshift z of a PNS all decrease at a given central energy density epsilon(c). For the higher-mass PNSs PSR J0740+6620 and PSR J0348+0432, the influence of hyperon interactions on compactness M/R and surface redshift z is significant. In contrast, for the lower-mass PNSs PSR J1614-2230 and PSR J0737-3039A, the effect on M/R and z is negligible.
Spectroscopy remains a cornerstone of modern physics and chemistry, providing critical insights into molecular structures and interstellar phenomena. Accurate interpretation of interstellar line spectra through radiative transfer modeling relies heavily on two essential types of molecular input data: spectroscopic information (including energy levels, transition probabilities, and statistical weights) and collisional data. However, the completeness and precision of these datasets are often limited, constraining the reliability of astrophysical models. This work explores the application of machine learning (ML) and artificial neural networks (ANNs) for predicting and reconstructing missing spectroscopic/collisional data. We analyze their potential to enhance spectral databases, thereby improving stellar spectral analyses and the determination of fundamental stellar parameters. The study also addresses key challenges, methodological limitations, and validation issues inherent to data-driven approaches. Finally, we discuss current progress, share practical experiences, and outline future prospects and research needs in the rapidly evolving field of computational spectroscopy.
We present a novel method to derive rotation curves of the inner broad-line region (BLR) of lensed quasars with light-day spatial resolution. The approach exploits microlensing distortions of the broad emission lines (BELs), where the strength of the effect in the line wings traces the size of the emitting region at different velocities. We analyze the high-ionization lines Si IV and C IV in five gravitationally lensed quasars, measuring microlensing amplitudes across several velocity bins. Bayesian inference yields emission-region sizes, which we confront with a Keplerian disk model. We find a smooth, monotonic increase in microlensing with velocity, and the derived velocity-size relations are consistent with disk-like rotation. These results provide the first direct evidence for Keplerian motion in the innermost BLR of quasars.
PKS 1510-089, a highly active flat-spectrum radio quasar, known for its frequent flaring activity across the electromagnetic spectrum. We present a decade-long analysis of its flux variability in optical bands and 7-rays, focusing on the non-thermal dominance parameter, H/3 and H7 lines, and the A5100 A & ring; continuum. We examine the H/3 flux and full width at half maximum (FWHM), along with the A5100 A & ring; continuum light curves to assess whether the primary source of continuum emission is the accretion disk or the jet during different activity periods. Our results highlight that jet emission dominates the continuum during flare-like episodes. We obtain an approximately 80 day delay between the H/3 and continuum emissions, which we interpret as the spatial separation between the optical emission region and the broad-line region (BLR). Near-zero delays between optical and near-infrared bands indicate co-spatial emission within the jet. Synchrotron self-Compton is identified as the dominant 7-ray mechanism during flares, supported by minimal delays with optical/NIR emission. A persistent anticorrelation between the H/3 FWHM and luminosity reveals a "breathing-BLR" effect, independent of whether ionization arises from the disk or jet. This relation also holds between H/3 FWHM and A5100 A & ring; luminosity during disk-dominated phases, suggesting that the emission line arises mostly from the canonical virialized BLR. Moreover, jet-related A5100 A & ring; flares coincide with H/3 flares, suggesting the jet base lies within the BLR. From 219 disk-dominated spectra, we estimate a mean black hole mass of MBH = (2.85 +/- 0.37) x 108 Mo. This study sheds light on the jet-BLR connection in PKS 1510-089, enhancing our understanding of blazar emission.
Planetary systems are formed in dense interstellar clouds where chemistry is driven by complex ion-molecule processes. To improve astrochemical models, we present theoretically calculated datasets of cross sections and rate coefficients for important molecular ions under astrophysical conditions. The results provide a dataset relevant to protoplanetary disks and laboratory plasmas, and support the development of a user-friendly platform for data dissemination within the Virtual Atomic and Molecular Data Center (VAMDC) and the Serbian Virtual Observatory (SerVO).
This paper highlights the importance of collisional processes in astrophysical environments, including the interstellar medium, planetary atmospheres, and laboratory studies. We emphasize the critical roles of heavy-particle ionization and dissociative recombination, underscoring the need for accurate cross-section data. Our research focuses on calculations of cross sections and rate coefficients needed for modeling. We also discuss future research directions.
This study examines radiative processes, with a focus on photodissociation, in non-symmetric hydrogen-silicon molecular systems. for the wide range of parameters. The results provide essential input for photochemical modeling in both laboratory plasmas and astrophysical contexts.
CaII and OI emission lines in active galactic nuclei (AGN) have been used as powerful diagnostic probes of the broad-line region (BLR) for the past 40 years. In particular, line ratio diagnostics have been used to constrain the physical conditions in the low-ionization phase of the BLR, while line width measurements have provided rough constraints on the location of the emission region relative to the Balmer-emitting phase of the BLR. However, due to limited observational capabilities, detailed line-profile studies of these lines- directly linking CaII and OI with structural BLR models-have only become possible very recently. Here, we present an overview of our most recent study that has enabled investigations of CaII and OI emission lines in unprecedented detail, directly linking CaII triplet emission profiles to the kinematics of a rotating disk. We focus on our results for NGC 4593, but we also provide an outlook on how CaII and OI open up a new observational window to probe the low-ionization part of the BLR in general.
We present a re-evaluation of the relationship between the Mg II lambda 2798 A & ring; emission line and the 3000 A & ring; continuum luminosity, including an analysis of the Baldwin Effect, using a sample of 40,685 radio-quiet quasars and 441 Flat Spectrum Radio Quasars (FSRQs). To address dispersion from AGN variability, we applied a binning technique after excluding over 3,000 radio-loud sources, resulting in a refined empirical correlation. Our findings reveal statistically significant differences in the slope of this relationship between RQ quasars and FSRQs, implying either intrinsic differences in their accretion disk spectra or a significant contribution from jet-induced continuum to the BLR ionization in FSRQs. Furthermore, our investigation of the Non-Thermal Dominance (NTD) parameter shows that a substantial fraction of both populations (43.8% of RQ quasars and 55.5% of blazars) exhibit NTD < 1. We interpret this in blazars as evidence that the accretion disk alone cannot power the BLR, while in RQ quasars, it may indicate BLR anomalies, continuum-line time lags, or UV continuum suppression by a strong corona. Finally, we demonstrate that the Baldwin Effect is a direct consequence of the fundamental line-continuum luminosity relationship.
The Vera C. Rubin Observatory, through its Legacy Survey of Space and Time, will soon start producing 10 million alerts on transient astronomical objects per night. Due to logistics and bandwidth, alerts will not be dispatched directly to the public but to 'brokers' i.e. tools selected by LSST to handle alert streams. Brokers offer both common, specific and micro-specific functionalities related to alert handling, analysis, representation and dissemination. In this ecosystem, potentially augmented by data streams from other astronomical sources, there is a - need demonstrated by the community - for use cases which combine features of individual brokers. In this paper we present initial efforts and a prototype of such a tool, along with a language that would allow users to define use cases / workflows in a manner tailored for the domain.
We present observational evidence supporting the presence of a stratified accretion disk wind in active galactic nuclei (AGN), based on multiwavelength spectroscopic analysis of broad and narrow emission lines. The diversity in emission line profiles, ionization potentials, and kinematic signatures suggests a structured outflow emerging from the accretion disk, with different zones contributing to specific spectral features. High-ionization lines (e.g., Civ lambda 1549) exhibit strong blueshifts and asymmetric profiles indicative of fast, inner profiles consistent with predominant emission from slower, denser regions farther out, although exhibiting systematic blueshifts in quasars radiating at high Eddington ratios. The intermediate ionization lines (e.g., Aliii lambda 1860) present a situation that is intermediate in terms of shift amplitudes, although in several super-Eddington candidates radial outflow velocity may reach values comparable to the ones of the high ionization lines. These results are consistent with radiatively driven wind models featuring radial stratification. We made preliminary photoionization modeling assuming unabsorbed radiation emitted from the corona and the hotter disk regions emission or absorbed by a layer of gas. Our findings provide new constraints on the geometry and physical conditions of AGN winds, providing clear evidence in favor of stratified wind emission.
Green Bean is a rare type of galaxy which represents a short-lived phase in the life cycle of active galactic nuclei (AGN), characterised by large-scale, powerful ionised clouds in the circumgalactic medium. Recent studies demonstrate that these extended ionised structures may reflect fading signatures of past AGN activity, often manifested in the form of large-scale ionisation cones. The analysis of their observational properties provides unique constraints on AGN lifetimes, feedback mechanisms, and transitions between radiative and kinetic modes of activity. In this paper we announce the first results of the project dedicated to the long-slit spectroscopic and scanning Fabry-Perot interferometric observations of Green Bean galaxies at the Russian 6-m telescope with SCORPIO-2 multi-mode instrument. We describe the data reduction and spectral fitting procedures that allow one to characterise ionisation conditions in extended gaseous regions of the galaxy SDSSJ095100.54+051026.7.
The analysis of the optical spectra of PMN J0948+0022 showed significant variations in the spectral lines that, when combined with the Fermi gamma-ray light curve and radio observations reported by other authors, were interpreted as the result of interactions between the relativistic jet and the narrow-line region (NLR). In this work, we present order-of-magnitude calculations of the energetics associated with this proposed jet-NLR interaction. We demonstrate that the observed outflows are capable of absorbing a fraction of the jet energy and converting it into kinetic energy. This mechanism provides a natural explanation for the optical spectral variability recorded with the X-shooter and Multi-Unit Spectroscopic Explorer (MUSE) instruments. Our results sup-port the scenario in which feedback from the relativistic jet can dynamically influence the circumnuclear gas, offering new insights into the coupling between jets and the NLR in gamma-ray-emitting narrow-line Seyfert 1 galaxies.
Blazars, a highly variable Active Galactic Nuclei (AGNs) subclass, provide a unique opportunity to explore the physical processes within their relativistic jets and emission regions. In this study, we investigate the multi-wavelength variability of the blazar TON 599, a Flat Spectrum Radio Quasar (FSRQ), with a particular emphasis on its emission line behavior. We focus on the Mg II lambda 2798 A & ring; emission line, a key tracer of the ionized gas in the broad-line region (BLR), and its role in jet-induced variability. In addition to optical emission lines, we analyze gamma-rays (0.1-300 GeV), X-rays (0.2-10 keV), optical continuum (lambda 3000 A & ring;), optical polarization, and millimeter-wavelength light curves. Three cross-correlation methods are employed to investigate temporal relationships between the emission line and continuum across various wavelengths. Using the Non-Thermal Dominance (NTD) parameter, our analysis confirms that synchrotron emission dominates the continuum during active states, highlighting the jet's primary role in the observed variability. The Mg II emission line exhibits quasi-simultaneous variability with the optical continuum, suggesting photoionization driven by the jet's non-thermal radiation. Additionally, the minimal time lag between gamma-ray and optical/nearultraviolet emissions supports a synchrotron self-Compton origin for the most variable component of the gamma-ray emission. These findings highlight the importance of emission line variability and multiwavelength observations in constraining the interaction between jets and the BLR in blazars. The results contribute to a deeper understanding of AGN emission mechanisms and the complex interplay between jets and their surrounding environments.
