reapxdev/zenodo-scraper huggingface dataset:
Interpreting and Fitting Asteroseismic Frequency Separation Ratios with Static Stellar Models
Authors: Lindsay, Christopher, Bellinger, Earl, Braun, Teresa
Type: Poster
Published: 2026-07-12

<p>The observed asteroseismic frequency separation ratios between the small and large frequency separations ($r_{\ell,\ell+2}(n)$) probe stellar core properties, providing a powerful diagnostic of the internal structures of main-sequence stars. Although these ratios are known to vary as stars evolve, the distinct effects of individual global and internal stellar parameters on them have not yet been clearly isolated and quantified. In this work, we compute static stellar models with systematically varied global properties and internal structures using \texttt{MESA}. By calculating oscillation mode frequencies and fitting linear combinations of Chebyshev polynomials to the relation between the separation ratios and radial-mode frequencies, we determine how $r_{\ell,\ell+2}(n)$ responds to changes in stellar mass, metallicity, core mass, central hydrogen abundance, and envelope hydrogen abundance. We further demonstrate how matching observed and model separation ratios can be used for asteroseismic inference, and compare results from static stellar models with those obtained from full evolutionary models.</p>
Chemical paradox in a binary system: Exploring the metal discrepancy in HD 81809 system
Authors: Moedas, Nuno
Type: Poster
Published: 2026-07-13

<p class="p1">Signals of planets being engulfed by their host stars are rare. Chemical transport mechanisms such as convection, atomic diffusion, turbulent mixing, and thermohaline mixing erase the chemical enrichment left by the planet. However, binary stars, which form together from the same material are expected to have the same initial chemical composition. From an observation point of view they could be used to detect <span class="s1">chemical differences caused by the accretion of a planet. Despite the fact that various investigations have </span><span class="s1">identified chemical discrepancies of 0.1–0.2 dex in stellar binaries, these variations could be attributed to </span><span class="s1">atomic diffusion alone.</span></p>
<p class="p1">HD 81809 is a binary star system with the primary component being a subgiant G-type star, and the secondary component being a main sequence G-type star. Recent spectroscopic analyses revealed a <span class="s1">difference in abundance, finding that HD 81809A is a metal-poor star with [Fe/H] = -0.57 dex, whereas </span><span class="s2">HD 81809B is estimated to have solar abundances with [Fe/H] = 0.00 dex. This large discrepancy cannot </span><span class="s2">be explained by atomic diffusion alone. This makes the HD 81809 system a unique laboratory in which to </span><span class="s3">test whether planet engulfment could explain the chemical discrepancy between the stellar companions. </span><span class="s2">Using stellar models from MESA that include accretion, we explored whether it was possible to enrich the </span><span class="s1">surface of HD 81809B to the observed values starting from a composition similar to that of HD 81809A. </span>Simulations suggest that a recent accretion event involving the capture of 25–75 Earth masses of rocky <span class="s1">material by HD 81809B could partially explain the chemical dichotomy in the binary system.</span></p>
Do Scaling Relations Need to be Modified to Fit Red Giants? A Case Study of gamma Per A
Authors: Ádám, Rozália, Molnár, László, Kalup, Csilla, Grundahl, Frank, Huber, Daniel
Type: Poster
Published: 2026-07-13

<p>$\gamma$ Persei is a long-period eclipsing binary system ($P\approx 14.6$ years), as well as a spectroscopic binary containing a red giant primary. We determined the seismic parameters $\nu_{\rm max}$, $\Delta \nu$, and the oscillation amplitudes of its primary component and estimated its seismic mass, which we compared to its estimated dynamic mass.</p>
<p>We used TESS data obtained during Sectors 85 and 86 and complemented the space-based observations with high-resolution RV measurements acquired by SONG during two distinct epochs in 2017 and 2024. We inferred a seismic mass of $3.27\pm0.13$ M$_\odot$ $\gamma$ Per A, which is slightly below the dynamical mass of $3.6\pm0.2$ M$_\odot$ (Diamant et al. 2023).</p>
<p>We found the photometric oscillation amplitudes to be significantly lower than predicted from scaling relations -- yet in line with other high-mass red giants. We also found that radial velocity amplitudes along the Hertzsprung-Russell diagram cannot be fitted uniformly with current scaling relations, with red dwarfs requiring $(L/M)^{1.5}$ scaling but $\gamma$ Persei requiring $(L/M)^{0.7}$.</p>
Seismic Characterization of a Homogeneous Sample of Main Sequence and Subgiant Solar-Type Kepler Stars
Authors: Díaz Reeve, Pedro, Serenelli, Aldo, Sayeed, Maryum, Huber, Daniel, Torki, Maryam
Type: Poster
Published: 2026-07-13

<p>In this work we present the most complete and physically consistent catalog of fundamental stellar parameters for 765 main sequence and subgiant stars observed by Kepler in short cadence. The catalog includes seismic masses, radii, surface gravities, and ages derived using asteroseismic constraints from the reanalysis of a homogeneous sample of oscillating solar-type stars<br>observed by the Kepler mission, presented by Sayeed et al. (2025), combined with spectroscopic constraints from multiple sources. The stellar parameters are inferred using grid-based modeling techniques and incorporating the best-fit evolutionary [α/Fe] ratios (Diaz Reeve & Serenelli 2026), resulting in a homogeneous and composition-consistent determination of stellar properties.</p>
Pol-Quake! Polarimetric Asteroseismology of Massive Hot Stars
Authors: Perkins, Jean, Cotton, Daniel, Buzasi, Derek, Bailey, Jeremy, De Horta, Ain, Boiko, Ievgeniia
Type: Poster
Published: 2026-07-13

<p><span>The evolution of the galaxy is inextricably linked to the evolution of massive stars, and yet they are some of the stars we know least about.  Asteroseismology is an indispensable tool for exploring the structures of stars, but it has a basic problem: determining mass, radius, age, and internal structure requires a mode solution.  The pulsations in massive stars are complex to disentangle—often with multiple solutions being geometrically feasible from photometric or spectroscopic data alone. Polarimetric observations can provide the necessary insight into the spatial structure of massive stars needed to reduce the number of possible mode solutions. </span></p>
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<p><span>Here we report on the progress of our observing program and highlight the results from our preliminary analysis of our two pilot-program stars. Three observing teams spanning a third of the globe have obtained data on a dozen $\beta$~Cep/SPB stars. From our initial polarimetric observations the most promising candidates for further analysis include $\eps$~Per, $\nu$~Eri, and $\lam$~Sco; the larger polarimetric signals, attributable to pulsations, are thus far seen in the $\beta$~Cep targets compared to SPBs. An update on $\beta$~Cru with double the amount of polarimetric data recovers the previously published results, and identifies possible new frequency matches in the polarimetric data.  Our initial examination of $\beta$~Cen indicates several frequencies identified in both photometry and polarimetry as well.</span></p>
Back to the ρ-Δν relation of δ Sct
Authors: García Hernández, Antonio, Mirouh, Giovanni
Type: Poster
Published: 2026-07-14

<p>During the last 3 decades, several methods to find patterns in the oscillation spectra of δ Sct stars have been proposed (Breger et al., 1993; Handler et al., 1997; García Hernández et al., 2009, 2013; Paparó et al., 2016; Bedding et al., 2020; Hasanzadeh et al., 2021). This pattern has been spotted as a Δν thanks to its relation with the stellar mean density (García Hernández et al., 2015; 2017). However, these last observational results were obtained using only 11 eclipsing binary systems.<br>In this work, we have gone through the recent literature to search for eclipsing binaries with a δ Sct component and stellar parameters obtained from the binary analysis. Oscillations frequencies from satellite observations are also required. We gathered a total of 75 systems so far.<br>We aim to confirm the ρ-Δν relation but avoiding the possible subjective bias that these methods have. Here we test different methods in order to automate the finding of Δν. We also discuss the reliability of all of them to find the correct mean density.</p>
Asteroseismology of HD 156424
Authors: Lovekin, Catherine, Davis, Serena, Khalack, Viktor
Type: Poster
Published: 2026-07-16

<p>D 156424 is a hot magnetic star in the Sco OB4 association, and has previously been identified as part of a binary system. Spectropolarimetric results show that the companion star is also strongly magnetic, and thus this is a rare example of a doubly magnetic hot binary. In this work, we present a more detailed analysis of Transiting Exoplanet Survey Satellite (TESS) data, including phase variation.  We find short term phase variation consistent with an oblique magnetic rotator, as well as long term phase variation consistent with the third element proposed by Shultz et al. (2021). We performed asteroseismic modelling of the star, and determined the pulsations are most likely associated with the primary of the system. Our best fit models are universally young, and we find the star is well fit by a model with M=8.1 solar masses. In our models, the observed p modes are all associated with the primary star. Although previous work on magnetic stars suggests the fields may be the result of past mergers, the characteristics of HD 156424 make this origin unlikely.</p>
Spin-down of red clump stars by mixed modes
Authors: Bordadágua, Beatriz, Ahlborn, Felix, Hekker, Saskia
Type: Poster
Published: 2026-07-16
Keywords: Angular momentum transport, Stellar rotation, Red giant

<p>Current stellar models predict core rotation rates for low-mass red giant branch (RGB) stars that are orders of magnitude higher than those inferred from asteroseismic observations. This highlights the need for transport processes that can efficiently redistribute angular momentum (AM) within radiative interiors. For instance, mixed modes in solar-like oscillators have been shown to extract some AM from the cores of RGB stars.<br>Here, we present the first calculations of AM transport by mixed modes all the way to the red clump. We find a significant spin-down of the core in the red clump, demonstrating that mixed modes can efficiently redistribute AM at this stage. To obtain a more complete picture of AM transport, we also include other physical processes, such as meridional currents and the magnetic Tayler instability, and determine their combined effect on the rotation profiles.</p>
Improvements to Asteroseismic Fitting of White Dwarfs in the Gaia Era
Authors: Dublin, Andrew, Bell, Keaton, Bischoff-Kim, Agnes
Type: Poster
Published: 2026-07-16

<p class="MsoNormal">     Pulsating white dwarf stars have complex interior structures that, in principle, can be probed by the resonant frequencies of their standing wave oscillations; these resonant frequencies manifest as measurable, periodic brightness variations at the surface of the star. The traditional approach used to match observed pulsation frequencies to those computed by stellar evolution models (to within uncertainties) is known as period-by-period asteroseismic fitting. However, there remain significant hurdles in achieving reliable results using the period-by-period fitting approach for white dwarfs, and improved methodologies are required to address these issues. In this poster, we present novel strategies to characterize precise asteroseismic solutions in the <em>Gaia</em> era. Firstly, we demonstrate that the computational burden of computing large grids of models can be reduced by interpolating model periods over coarse grids. Second, we show how by incorporating absolute magnitude from <em>Gaia</em> astrometry into the statistical quality function used in the period-by-period fitting, solution degeneracy is significantly reduced. Lastly, we present a new method of isolating seismic solutions in a degenerate solution space based on fixed mode identification. By fitting Gaussian distributions to the resulting solutions, we can more accurately characterize the precision and degeneracy of the asteroseismic constraints.</p>
Klimawandel und Geopolitik in der Arktis
Authors: Brendel, Heiko, Scheffran, Jürgen
Type: Poster
Published: 2026-08-03
Keywords: Arktis, Klimwande, Geopolitik, Militärstrategie, Ressourcenkonkurrenz, Geopolitics, Arctic, climate change, geopolitics, military strategy, resource competition

<p>Das Poster gibt einen Überblick über die Wechselwirkungen von Klimawandel und Geopolitik in der Arktis. Die Region erwärmt sich mindestens dreimal so schnell wie der globale Durchschnitt; abschmelzendes Meereis und tauender Permafrost verstärken diesen Trend und erhöhen Kipppunkt-Risiken im Erdsystem. Wirtschaftlich eröffnet der Eisrückgang neue Schifffahrtsrouten und leichteren Zugang zu Rohstoffen, birgt aber Risiken für Ökosysteme und Infrastruktur. Geopolitisch gewinnt die Arktis durch die acht Anrainerstaaten und Chinas wachsende Präsenz als selbsternanntem "arktisnahem Staat" an Gewicht. Die Region ist zentral für Raketenfrühwarnsysteme; zugleich macht schmelzendes Meereis U-Boote, bislang durch die Eisdecke geschützt, zunehmend verwundbar und untergräbt etablierte nukleare Abschreckungslogiken. US-Annexionspläne für Grönland und Kanada stellen die NATO als geeinten Akteur infrage. Truppenkonzentrationen auf Kola, in Nordnorwegen und Alaska sowie die GIUK-Lücke zeigen den Ausbau militärischer Kapazitäten. Erschwerte Satellitennavigation begrenzt den Drohneneinsatz, treibt aber Innovation voran. Das Poster zeigt, wie Klimawandel, Ressourcenkonkurrenz und Aufrüstung Konfliktrisiken und Kooperationschancen verschärfen.<br>***<br>This poster outlines the interlinkages between climate change and geopolitics in the Arctic. The region is warming at least three times faster than the global average; melting sea ice and thawing permafrost amplify this trend and raise the risk of self-reinforcing tipping points in the Earth system. Economically, retreating ice opens new shipping routes and eases access to resources, while posing risks to ecosystems and infrastructure. Geopolitically, the Arctic gains weight through its eight littoral and stakeholder states and China's growing presence as a self-declared "near-Arctic state". The region is central to missile early-warning systems; at the same time, melting sea ice, which has long shielded submarines, makes them increasingly vulnerable and undermines established deterrence logics. US annexation plans for Greenland and Canada call NATO's cohesion into question. Troop concentrations on Kola, in northern Norway, and in Alaska, plus the strategic GIUK gap, illustrate the military buildup. Difficult satellite navigation limits drone use while driving innovation. The poster shows how climate change, resource competition, and rearmament heighten both conflict risks and cooperation opportunities in the Arctic.</p>
Inferring the masses and ages of SX Phoenicis stars in globular clusters
Authors: Dréau, Guillaume, Daszynska-Daszkiewicz, Jadwiga, Szewczuk, Wojciech, Góra, Paulina
Type: Poster
Published: 2026-07-17

<p><span><span>SX Phoenicis (SX Phe) stars are pulsating blue straggler stars commonly observed in Galactic globular clusters such as M55, 47 Tucanae and Omega Centauri. Their pulsational properties, together with the stellar parameters accessible through photometric and astrometric observations, make them promising laboratories for studying the formation and evolution of blue stragglers. However, despite numerous observational studies, several fundamental stellar parameters, including mass, age, and helium abundance, remain poorly constrained for many SX Phe stars. These quantities are nevertheless essential for discriminating between the proposed blue straggler formation channels, such as stellar collisions or binary mass transfer.<br><br>In this project, we investigate whether the currently available observational constraints are sufficient to infer the fundamental properties of SX Phe stars through Bayesian stellar modelling. We combine multi-band photometric observations, together with effective temperatures and surface gravities, parallaxes, and metallicities. These observables are analysed using BASTA, a Bayesian framework based on the BaSTI stellar evolution grid, to derive preliminary constraints on the masses and ages of SX Phoenicis stars in globular clusters prior to detailed seismic modelling.<br></span></span></p>
HAYDN eyes on classical pulsation
Authors: Suárez, Juan Carlos, García Hernández, Antonio, Mirouh, Giovanni, Camino Mesa, Carlos Casimiro, Florido Tomé, Alejandro José
Type: Poster
Published: 2026-07-20

<p>The ESA M8 candidate mission HAYDN will open a new observational window for the study of classical stellar pulsation in dense stellar environments. Designed to deliver long-duration, high-precision photometry in crowded fields, HAYDN will provide unprecedented opportunities to investigate pulsating stars in stellar populations that remain largely inaccessible to current and planned space missions.</p>
<p>In this poster, we present the scientific potential of HAYDN for investigating pulsating Blue Straggler Stars (BSS). Likely formed through mass transfer or dynamical interactions in dense stellar environments, some of the observed BSS lie within  the  δ Scuti- and γ Doradus-like instability strip. Their seismic properties offer a unique opportunity to probe their internal structure and to constrain the physical processes responsible for their formation and subsequent evolution. HAYDN will provide unprecedented access to such objects in globular clusters and ω Centauri.</p>
<p>Beyond old stellar populations, HAYDN will observe the young cluster χ+h Persei, providing homogeneous samples of A–F stars, which offers a unique opportunity to investigate the pulsational behaviour of δ Scuti and γ Doradus stars under well-controlled conditions, enabling ensemble studies of rotation, mixing processes, and stellar evolution.</p>
<p>In addition, the large number of field stars expected within the HAYDN FoV will deliver extensive samples of pulsating stars across the classical instability strip, allowing to explore classical pulsation across a broad range of stellar populations, ages, metallicities, and evolutionary pathways.</p>
The Youngest Stars in PLATO's LOPS2: Towards an Automated Variability Classifier for Young Stellar Objects
Authors: Scheller, Nena, Zwintz, Konstanze
Type: Poster
Published: 2026-07-23

<p>As part of the complementary science preparation for the ESA mission PLATO (PLAnetary Transits and Oscillations of stars), an automated stellar variability-classification framework has been developed using TESS observations of the PLATO field LOPS2. While the current classifier successfully identifies many classical types of stellar variability, it is not designed to capture the complex and often irregular photometric behavior of Young Stellar Objects (YSOs).</p>
<p>Young stars exhibit a broad range of variability phenomena arising from both stellar and circumstellar processes. In addition to pulsations, periodic rotational modulation caused by starspots, and eclipses, YSOs commonly show pseudo-periodic and non-periodic variability linked to accretion processes and variable circumstellar extinction. </p>
<p>To address this limitation, we investigate the young stellar population in the PLATO long-pointing field LOPS2 using existing high-cadence photometric observations from TESS. We present a variability survey of stars in young star-forming regions, clusters, and associations located within the LOPS2 field, with the goal of characterizing the diversity of YSO variability behavior.</p>
<p>This work forms the basis for the development of a dedicated machine-learning-based classifier for young stellar variability. Trained on light curves that will include periodic, semi-periodic, and stochastic YSO variability, the tool is intended to complement the general PLATO variability classification pipeline. Initial validation will use TESS observations before application to early PLATO data.</p>
SX Phoenicis Stars in M55: Double-Mode Radial Pulsators from a Reanalysis of CASE Photometry
Authors: Szewczuk, Wojciech, Daszynska-Daszkiewicz, Jadwiga, Dréau, Guillaume, Paulina Gora, Walczak, Przemysław
Type: Poster
Published: 2026-08-02

<p>We present a reanalysis of photometric time-series data for SX Phoenicis stars in the globular cluster M55 obtained within the CASE Project. By performing a new frequency analysis of the light curves, we derived new pulsational solutions for the studied variables and investigated characteristic period ratios indicative of radial pulsation modes. For 7 stars, we identified period ratios consistent with radial modes, providing valuable constraints for asteroseismic interpretation. These mode identifications enabled seismic modelling using a Monte Carlo-based Bayesian approach.</p>
Building the Foundations for an APO-TESS Catalo: The APOGEE Asteroseismic Target List
Authors: Howell, Madeline, Johnson, Jennifer, Pinsonneault, Marc
Type: Poster
Published: 2026-07-27

<p class="p1">The all-sky TESS mission provides an unprecedented opportunity to study the oscillations in red giants in a wide range of Milky Way stellar populations. When combined with large spectroscopic surveys, these asteroseismic measurements enable precise estimates of stellar masses, radii, and ages. Despite efforts to <span class="s1">target asteroseismic candidates within the APOGEE DR19 survey, only 12% of red giants with literature </span>TESS asteroseismic detections have corresponding APOGEE spectra. To investigate the cause of this <span class="s2">disparity, we have constructed an APOGEE asteroseismic target list to identify stars with high potential for </span>detectable oscillations. Using spectroscopic surface gravities and effective temperatures from APOGEE <span class="s2">DR19, we estimate oscillation detection probabilities for all giant stars in the survey. For stars with detection </span>probabilities greater than 50%, we further calculate a crowding metric to assess potential contamination <span class="s2">arising from the large TESS pixel scale, enabling prioritisation of relatively isolated targets for future analysis.</span></p>
<p class="p2">This APOGEE Asteroseismic Target List is a precursor for an APO-TESS catalog, which will build <span class="s2">upon the successful legacies of APOKASC and APO-K2 that are widely used in Galactic archaeology studies. </span><span class="s2">Preliminary estimates suggest that we will be able to seismically and spectroscopically characterise 316,000 </span>stars in APO-TESS, which is an increase by an order of magnitude compared to the Kepler-APOGEE <span class="s2">catalogs. This larger sample of well-characterised stars will enhance investigations of Galactic archaeology, </span><span class="s1">and also allow for analyses of diverse stellar populations that were not as accessible with the small fields of </span><span class="s2">view of the Kepler missions. Moreover, this work provides a valuable framework for future missions such as </span><span class="s1">Roman, which is also expected to yield large seismic samples of 300,000 stars in the Galactic bulge.</span></p>
conformeR: Conformalized Differential Expression Analysis of Multi-Condition Single-Cell Data
Authors: Leclerc, Justine, Seiler, Christof
Type: Poster
Published: 2026-02-10

<p>Poster presented at LS2 (Life Sciences Switzerland) Annual Meeting and Latsis Symposium 2026: The history of epidemics - are there lessons for the future?, in February 2026.</p>
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Online-Fernleihe im KOBV
Authors: Palme, Anna, Lohrum, Stefan
Type: Poster
Published: 2026-08-03
Keywords: Fernleihe

<p><span>Das Poster "Online-Fernleihe im KOBV." wurde auf dem 24. KOBV-Forum 2026 am 02.07.2026 beim Meet and Greet der KOBV-Services vorgestellt.</span></p>