Our Work

KZ Hydrae is a field SX Phoenicis star pulsating in a dominant radial mode with a frequency of 16.804 d$^{-1}$. Its low metallicity and kinematics indicate membership of the Galactic halo. The star is…

KZ Hydrae is a field SX Phoenicis star pulsating in a dominant radial mode with a frequency of 16.804 d$^{-1}$. Its low metallicity and kinematics indicate membership of the Galactic halo. The star is also the primary component of a long-period binary system with an orbital period of 26.8 ± 0.2 years and a secondary that is most likely a white dwarf. Such a configuration suggests that KZ Hya is a blue straggler formed through mass transfer. The star was observed by the TESS satellite in Sectors 63, 90, and 100. Our frequency analysis of the TESS light curves recovered the know dominant pulsation frequency and revealed additional independent peaks that can only be attributed to non-radial modes. We computed binary-evolution models using the binary module of the MESA code. Owing to the very long orbital period, we considered Bondi–Hoyle–Lyttleton (BHL) accretion and imposed observational constraints on the effective temperature, luminosity and orbital parameters. We adopted a white-dwarf companion with a mass of at least 0.75 M$_⊙$. Our modelling indicates that the formation of KZ Hya through stellar-wind accretion is the most plausibly scenario, leading to an increase of the accretor mass of by up to 10 per cent. In the next step, we constructed seismic binary-evolution models of KZ Hya that reproduce the frequency of the dominant radial mode. We finish with by comparing these results with seismic modeling obtained from single-star evolutionary calculations using Bayesian inference.

Abstract: Asymmetries in the observed rotational splittings of a multiplet contain information about the star’s rotation profile and internal magnetic field. Moreover, the frequency regularities…

Abstract: Asymmetries in the observed rotational splittings of a multiplet contain information about the star’s rotation profile and internal magnetic field. Moreover, the frequency regularities of multiplets can be used for mode identification. However, to exploit this information, highly accurate theoretical predictions are needed. In the case of massive main sequence pulsators, β Cephei pulsators, the effect of rotation on the mode asymmetries cannot simply be neglected, hindering measurements of internal magnetic fields through signatures in the observed asymmetries. In this talk, I will quantify the difference in the predicted mode asymmetries between a 1D perturbative method and a 2D method that includes a 2D stellar structure model, which takes rotation into account self-consistently without any simplifying assumptions. I will then place these differences between 1D and 2D methods in the context of asteroseismic measurements of internal magnetic fields. In other words, ‘what would be the difference in the measured magnetic field strength when the rotation is treated in a 1D perturbative manner versus a 2D non-perturbative manner?’. For the 1D perturbative method, the newly developed open-source pulsation code StORM is coupled to the 2D stellar structure code ESTER and is compared with the oscillation predictions from the 2D TOP pulsation code, where for the 1D case, a non-rotating ESTER model is used. We focus on models representative of rotating β Cephei pulsators spinning at up to 20 per cent of the critical Keplerian rotation rate, and specifically on low-radial-order gravity and pressure modes. Differences in the predicted mode asymmetries of a rotating star between 1D perturbative methods and 2D non- perturbative methods can greatly hinder accurate measurements of internal magnetic fields in main-sequence pulsators with low-order modes. Nevertheless, I will discuss under what circumstances accurate measurements could be achieved.

The transport of angular momentum and the mixing of chemical elements induced by shear instabilities in stably stratified stellar radiative regions remain major sources of uncertainty in stellar model…

The transport of angular momentum and the mixing of chemical elements induced by shear instabilities in stably stratified stellar radiative regions remain major sources of uncertainty in stellar modelling. In the context of ongoing efforts to characterise and model stellar interiors, it is essential to develop consistent frameworks capable of treating dynamical processes such as shear instabilities across all regimes of stratification and rotation. However, many analytical and numerical works only partially account for the Coriolis acceleration, often neglecting the horizontal component of the rotation vector (referred to as the “traditional approximation of rotation”) and therefore fail to address regimes in which rotation competes with or dominates stratification. In this contribution, we present recent efforts to understand the non-linear regime of horizontal shear instabilities taking into account the full Coriolis acceleration. We first show how stratification and rotational effects modify the dynamics of horizontally sheared flows and the turbulence they trigger. We then investigate how the variation of thermal diffusion also affect the turbulent transport of this instability. These developments are devoted to improve the parameterisation of shear-induced turbulence in stellar evolution models.

ABSTRACT: The concept of financial security among youth has evolved significantly with the emergence of digital financial products. Among these, small-ticket “pocket insurance” or micro-in…

ABSTRACT: The concept of financial security among youth has evolved significantly with the emergence of digital financial products. Among these, small-ticket “pocket insurance” or micro-insurance has gained traction due to its affordability, accessibility, and relevance to modern lifestyles. This study investigates the impact of such insurance products on the financial security of young individuals. This research uses survey data and analysis to look at how much people know about micro-insurance, how they use it, what benefits they see, and what challenges they face. The results show that pocket insurance helps improve financial resilience, especially for students and young professionals, but there are still issues with awareness and trust. The study ends with suggestions to improve outreach, product design, and policy support to make financial inclusion better.

We present the results of an analysis of 276 high mass X-ray binaries in the Large and Small Magellanic Clouds, using custom light curves from TESS FFI data and spanning the first seven years of the m…

We present the results of an analysis of 276 high mass X-ray binaries in the Large and Small Magellanic Clouds, using custom light curves from TESS FFI data and spanning the first seven years of the mission. HMXBs consist of an O/B-type donor star and a compact accretor; understanding the physics of these systems is key to building out our picture of massive star binary evolution pathways and gravitational wave progenitor events. At present, the rate of HMXB mass transfer, and thus orbital decay, is poorly constrained. The aim of this study was to use TESS to follow up on 80 systems with orbital periods from decades of X-ray and optical monitoring of the Magellanic Clouds, and to search for optical counterparts in the remaining sample for future long-term monitoring. However, the more exciting result has been the prevalence of stochastic low-frequency (SLF) variability among the donor stars in these systems, for systems both with and without known orbital periods. The detection of SLF in HMXBs allows us to further characterize stellar interiors across all stages of massive star binary evolution. We do not detect SLF for HMXBs with literature periods under 11 days, suggesting a potential connection to tidal suppression of oscillation; however, we note that several reported 1 day periods in fact appear to be SLF, not signatures of binarity. We also report detections of ellipsoidal variability that largely do not align with literature periods. This underscores the importance of signal deblending in crowded fields, as well as thorough characterization of all types of variability in massive stars. Finally, for the well-known system SMC X-1, we retrieve a strong detection of an orbital period of 3.89 days, showing remarkable consistency with measurements over the past 40 years and allowing us to place an upper limit on its mass transfer rate. Detailed analysis of SMC X-1 across multiple years reveals variation in the period on the order of minutes, likely due to tidal effects, and illustrates a blueprint for detailed long-term monitoring of bright extragalactic objects with TESS.

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Additional Materials for the Manuscript: "Fear Conditioning Research Through the Lens of Meta-Analyses: A Systematic Methodological Review", including screening procedures, review table, plots, etc.&n…

Additional Materials for the Manuscript: "Fear Conditioning Research Through the Lens of Meta-Analyses: A Systematic Methodological Review", including screening procedures, review table, plots, etc.    plot_sheet.tsv Reduced version of the extraction_sheet with relevant information for plotting extraction_sheet.tsv All extracted information of the included articles FT_screening.tsv Articles and decisions of the full-text screening title_abstract_screening.csv Articles and decisions of title and abstract screening   Code for the plots can be accessed via the linked GitHub repository.

Classical Cepheid variables are essential in our understanding ofstellar pulsation. Cepheids that pulsate in the first overtone modeoften exhibit low-amplitude additional variability at themillimagnit…

Classical Cepheid variables are essential in our understanding ofstellar pulsation. Cepheids that pulsate in the first overtone modeoften exhibit low-amplitude additional variability at themillimagnitude level. Signals that appear at period ratios$P_{X}/P_{1O}\in[0.60; 0.65]$ are theorized to be associated withnon-radial modes and have been extensively studied in Cepheids of theLarge Magellanic Cloud (LMC) with the Optical Gravitational LensingExperiment (OGLE). Non-radial modes have also been detected in asignificant fraction of the Galactic Cepheid sample with TESS.In this work, we show that these low-amplitude features can also bedetected in the LMC with TESS, despite its poor spatial resolution,which does not favor observations in crowded stellar fields. Most LMCCepheids are located in the Continuous Viewing Zone, which allows theanalysis of longer uninterrupted light curves and the detection oftemporal variations. After careful detrending and stitching of thelight curves, the required precision for a large fraction of LMCCepheids can be achieved.Our sample consists of nearly four hundred stars. We have analysed thecurrently available TESS-Gaia light curves extracted from Full FrameImages gathered with 30 minute and 10 minute cadence from the Primeand First Extended missions, respectively. We use standard Fouriertechniques to recover the low-amplitude modes. We verify non-radialmodes in 94 stars that were first detected with OGLE. Thedetectability of these modes with TESS and OGLE are compared. We alsoidentify a number of new candidates for non-radial pulsation.

This deliverable is the PRIME-6G Project Handbook, where all the project management and quality assurance procedures are recorded. Its main objective is to maintain a record of the different , process…

This deliverable is the PRIME-6G Project Handbook, where all the project management and quality assurance procedures are recorded. Its main objective is to maintain a record of the different , processes, tools and practices that is easily accessible to all partners.

В статье исследуются номинационные цепочки персонажей русских и узбекских народных сказок как средство текстовой организации и динамической характеристики героя. Изменение наименования персонажа обусл…

В статье исследуются номинационные цепочки персонажей русских и узбекских народных сказок как средство текстовой организации и динамической характеристики героя. Изменение наименования персонажа обусловлено развитием сюжета, сменой социальной или родственной роли, трансформацией внешнего облика, изменением точки зрения говорящего, а также приобретением героем нового статуса или характеристики. В русских сказках особую роль играют номинационные переходы, связанные с волшебным превращением и родственными отношениями персонажей; в исследованном узбекском материале заметное место занимают социально-ролевые, статусные и репутационно обусловленные повторные номинации. Устанавливается, что номинационная цепочка выполняет идентифицирующую, текстообразующую, характеризующую и сюжетно-динамическую функции.