Showing new listings for Tuesday, 7 October 2025

[olozhika]

Showing new listings for Tuesday, 7 October 2025

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

阅读 Usage.md了解如何使用此repo实现个性化的Arxiv论文推送

See Usage.md for instructions on how to personalize the repo.

Keyword list: ['star formation', 'star-forming', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', ' AGN ', 'standard candle', 'X-ray binar', 'solar corona']

Today: 16papers

Threading the Magellanic Needle: Hypervelocity Stars Trace the Past Location of the LMC

• Authors: Scott Lucchini, Jiwon Jesse Han

• Subjects: Subjects:
  Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2510.03393

• Pdf link: https://arxiv.org/pdf/2510.03393

• Abstract
  Recent discoveries have shown that a population of hypervelocity stars (HVSs) originate from the Large Magellanic Cloud (LMC). We use three such HVSs as dynamical tracers to constrain the past orbit of the LMC. Since each star was ejected at a finite time in the past, it must intersect the past position of the LMC's central black hole at its ejection time. We model the LMC's orbit under the influence of dynamical friction and extended mass distributions for both the LMC and the Milky Way, generating a large ensemble of orbital realizations. By evaluating which orbits intersect the back-integrated HVS trajectories, we compute posterior distributions over the LMC's orbital history. This approach provides significantly tighter constraints on the past motion of the LMC than previously possible. We find two previously published orbital models that are consistent with these new constraints: a first-passage trajectory from a self-consistent hydrodynamic simulation, and a second-passage trajectory from a collisionless N-body simulation. In parallel, we infer the present-day ejection site of the HVSs -- likely tracing the LMC's dynamical center and supermassive black hole -- independent of conventional methods.

Faint supernovae and hyper-runaway white-dwarfs from single He-detonation in double HeCO-white-dwarf mergers

• Authors: Hila Glanz, Hagai B. Perets, Aakash Bhat

• Subjects: Subjects:
  High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2510.03396

• Pdf link: https://arxiv.org/pdf/2510.03396

• Abstract
  We present three-dimensional hydrodynamical simulations of mergers between low-mass hybrid HeCO white dwarfs (WDs), offering new insights into the diversity of thermonuclear transients. Unlike previously studied mergers involving higher-mass HeCO WDs and CO WDs, where helium detonation often triggers core ignition, our simulations reveal incomplete helium shell detonations in comparable-mass, lower-mass WD pairs. The result is a faint, rapidly evolving transient driven by the ejection of intermediate-mass elements and radioactive isotopes such as $^{48}$Cr and $^{52}$Fe, without significant $^{56}$Ni production. These transients may be detectable in upcoming wide-field surveys and could account for a subset of faint thermonuclear supernovae. Long-term evolution of the merger remnant shows that high-velocity PG-1159-type stars might be formed through this scenario, similar to normal CO-CO white dwarf mergers. This work expands our understanding of white dwarf mergers and their implications for nucleosynthesis and stellar evolution.

The impact of internal versus external perturbations on close-in exoplanet architectures

• Authors: Christina Schoettler, James E Owen

• Subjects: Subjects:
  Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2510.03401

• Pdf link: https://arxiv.org/pdf/2510.03401

• Abstract
  Young planetary systems are subjected to different dynamical effects that can influence their orbital structure over time. In systems with more than one planet, other planets can internally influence each other, e.g. via planet-planet scattering. External perturbing effects also need to be taken into account, as stars do not form by themselves but together with other stars in young star-forming regions. This birth environment can externally affect young multi-planet systems, e.g. via fly-bys. Previous work has shown that the absence/presence and location of an outer giant planet around a close-in planet system do not change how these inner planets react to a single fly-by with another star. We further explore this by comparing the effects of these external perturbations on four close-in sub-Neptune planets to those caused by a situation where only the distant giant is perturbed by the same kind of encounter. Our results indicate that the close-in planet systems have a "preferred" end state after 500 Myr, which is reached regardless of how it was perturbed. In addition, the mass of the giant appears not to impact the reaction of the inner planet system in the scenario of an external perturbation in our tested set-ups, i.e. either a single 1 or 5 M_Jup giant placed at 2.5, 5, 10 or 20 au. However, the mass affects the subsequent evolution of the inner planets if only internal perturbations by the giant are considered. The reduction in mass leads to an absence of collisions during the 500 Myr.

ALMA-IMF. XXI.: N$_2$H$^+$ kinematics in the G012.80 protocluster: Evidence for filament rotation and evolution

• Authors: J. Salinas, A. M. Stutz, R. H. Álvarez-Gutiérrez, N. A. Sandoval-Garrido, F. Louvet, R. Galván-Madrid, F. Motte, M. Armante, T. Csengeri, J. Braine, A. Ginsburg, M. Valeille-Manet, L. Bronfman, P. Sanhueza, D. Díaz, G. Busquet, A. Koley, M. Bonfand, M. Fernández-López, N. Castro-Toledo, R. Veyry, G. Bernal-Mesina

• Subjects: Subjects:
  Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2510.03447

• Pdf link: https://arxiv.org/pdf/2510.03447

• Abstract
  (abridged) We aim to characterize kinematic processes in the G012.80 protocluster. We principally focus on the N$2$H$^+$(1$-$0) emission to trace the dense and cold gas. Additionally, we use lines such as DCN(3$-$2), H41$\alpha$, C$^{18}$O(1$-$0), and SiO(5$-$4), as well as continuum maps. We perform a N$2$H$^+$ hyperfine spectral line fitting to analyze multiple velocity components and spectral parameters. We estimate velocity gradients, column densities, and line-mass profiles for the two main filaments in G012, named R1 and R2. Line-mass profiles follow $\lambda$($\omega$) = 5660 M${\odot}$ pc$^{-1}$($\omega$/pc)$^{0.30}$ (R1) and $\lambda$($\omega$) = 6943 M${\odot}$ pc$^{-1}$($\omega$/pc)$^{0.20}$ (R2), which are much larger than those of typical low-mass filaments. R1 and R2 show disparate position-velocity (PV) features. R1 exhibits a transverse velocity gradient of 10.4 kms$^{-1} $pc$^{-1}$ and few dense cores. This gradient is interpreted with a simple rotation toy model, combined with line-mass profile, and corresponds to a rotational timescale of 0.1 Myr. In contrast, R2 exhibits compact velocity structures ($\Delta$V < 2 kms$^{-1}$), likely due to collapse, as evidenced by the presence of a comparatively large number of massive cores and protostellar outflows. R2 is forming prestellar and protostellar cores at a rate of 55.3 M${\odot}$ Myr$^{-1}$, with an efficiency similar to the Orion Integral Shaped Filament (ISF). The R1 filament, in contrast, lacks protostellar cores and only contains a few prestellar cores, resulting in an estimated SFR of 4.2 M${\odot}$ Myr$^{-1}$, more than an order of magnitude below that of R2. Combining these lines of evidence, we suggest that R1 is younger and still rotating, while R2 has evolved to collapse with a higher SFR. G012 thus hosts filaments at different evolutionary stages.

Woven by the Whirls: The growth and entrainment of cold clouds in turbulent hot winds

• Authors: Ritali Ghosh, Max Gronke, Prateek Sharma, Alankar Dutta

• Subjects: Subjects:
  Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2510.03552

• Pdf link: https://arxiv.org/pdf/2510.03552

• Abstract
  Galactic and intergalactic flows often exhibit relative motion between the cold dense gas and the hot diffuse medium. Such multiphase flows -- involving gas at different temperatures, densities, and ionization states -- for instance, galactic winds, are frequently turbulent. However, idealized simulations typically model the winds and driven turbulence separately, despite their intertwined roles in galaxy evolution. To address this, we investigate the survival of a dense cloud in a hot wind subject to continuous external turbulent forcing. We perform 3D hydrodynamic simulations across a range of turbulent Mach numbers in the hot phase $\mathcal{M}{\rm turb}=v{\rm turb}/c_{\rm s, wind}$ from 0.1 to 0.7 ($c_{\rm s, wind}$ and $v_{\rm turb}$ being the sound speed and the turbulent velocity in the hot phase, respectively). We find that in spite of the additional subsonic turbulence, cold clouds can survive if the cooling time of the mixed gas $t_{\rm cool, mix}$ is shorter than a modified destruction time $\tilde{t}{\rm cc}$, i.e., $t{\rm cool,mix}/\tilde{t}{\rm cc}<1$ where $\tilde{t}{\rm cc}=t_{\rm cc}/(1+\left(\mathcal{M}{\rm turb}/\left(f{\rm mix}\mathcal{M}{\rm wind}\right)\right)^2)^{1/2}$, where $f{\rm mix}\sim0.6$ is a fudge factor. Moreover, in the `survival regime', turbulence can enhance the growth of cold clouds by up to an order of magnitude because of more efficient stretching and an associated increase in the surface area. This increase in mass transfer between the phases leads to significantly faster entrainment of cold material in turbulent winds. In contrast to the narrow filamentary tails formed in laminar winds, turbulence stretches the cold gas orthogonally, dispersing it over a larger area and changing absorption line signatures.

Formation and growth of intermediate-mass black holes in dense star clusters: Lessons from N-body and MOCCA Monte Carlo Simulations

• Authors: Abbas Askar, Marcelo C. Vergara, Sohaib Ali

• Subjects: Subjects:
  Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2510.03766

• Pdf link: https://arxiv.org/pdf/2510.03766

• Abstract
  Dense star clusters are promising nurseries for the formation and growth of intermediate-mass black holes (IMBHs; $\sim 10^2-10^5,\mathrm{M}{\odot}$), with increasing observational evidence pointing to their presence in massive star clusters and stripped dwarf-galaxy nuclei. During the early evolution of compact clusters, massive stars can rapidly segregate to the center, where frequent collisions may trigger the runaway growth of a very massive star (VMS). This object can subsequently collapse to form an IMBH or merge with a stellar-mass black hole. We carried out direct $N$-body and Monte Carlo simulations of star clusters with initial core densities between $10^6$ to $4\times 10^8,\mathrm{M}{\odot},\mathrm{pc}^{-3}$ and total masses of $5.9\times 10^5$ and $1.3\times 10^6,\mathrm{M}{\odot}$. These models show that IMBHs of $10^3-10^4,\mathrm{M}{\odot}$ can form within $\leq 5$ Myr through the runaway collision channel. At later times, the IMBHs continue to grow through mergers with black holes, stars, and compact remnants, providing predictions testable with future gravitational-wave and transient surveys.

The Milky Way - Large Magellanic Cloud Interaction with Simulation Based Inference

• Authors: Richard A. N. Brooks, Jason L. Sanders, Vedant Chandra, Nicolás Garavito-Camargo, Adam M. Dillamore, Adrian M. Price-Whelan, Yuan-Sen Ting

• Subjects: Subjects:
  Astrophysics of Galaxies (astro-ph.GA)

• Arxiv link: https://arxiv.org/abs/2510.04735

• Pdf link: https://arxiv.org/pdf/2510.04735

• Abstract
  The infall of the Large Magellanic Cloud (LMC) into the Milky Way (MW) has displaced the MW's centre of mass, manifesting as an observed reflex motion in the velocities of outer halo stars. We use a Simulation Based Inference framework to constrain properties of the MW, LMC and the induced reflex motion using the dynamics of outer MW halo stars. Specifically, we use the mean radial and tangential velocities of outer halo stars calculated in a set of distance and on-sky bins. We train neural networks to estimate parameter posterior distributions using a set of $128,000$ rigid MW--LMC simulations conditioned upon velocity data from the Dark Energy Spectroscopic Instrument (DESI) and the combined H3+SEGUE+MagE outer halo surveys. We constrain the reflex motion velocity and the enclosed MW and LMC masses within $50 , \rm kpc$ using the DESI or H3+SEGUE+MagE dataset while varying the survey sky coverage and depth. We find the most precise constraints by using the radial and tangential velocity data from the H3+SEGUE+MagE survey and on-sky quadrant sky coverages. We report a reflex motion velocity, the speed at which the MW lurches towards the LMC, of $v_{\rm{travel}} = 26.4^{+5.5}{-4.4} , \rm km , \rm s^{-1}$, while simultaneously finding an enclosed LMC mass of $M{\rm LMC}(< 50 , \rm kpc) = 9.2^{+1.9}{-2.3} \times 10^{10}, \rm M{\odot}$ and enclosed MW mass of $M_{\rm MW}(< 50 , \rm kpc) = 4.4^{+0.7}{-0.7} \times 10^{11}, \rm M{\odot}$. Our results suggest that the LMC's total mass is at least $\approx 10-15 %$ of that of the MW. This inference framework is flexible such that it can provide rapid and reliable constraints when applied to any future survey measuring the velocities of outer halo stars.

Characterizing the variability of a sample of massive stars in eclipsing binaries

• Authors: C.I. Eze (1 and 2), G. Handler (1), F.Kahraman Aliçavuş (3), T. Pawar (4), A. Miszuda (1) ((1) Nicolaus Copernicus Astronomical Center, Warsaw, Poland, (2) Department of Physics and Astronomy, University of Nigeria, Nsukka, Nigeria, (3) Çanakkale Onsekiz Mart University, Faculty of Sciences, Physics Department, Çanakkale, Türkiye, (4) Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Toruń, Poland)

• Subjects: Subjects:
  Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2510.04746

• Pdf link: https://arxiv.org/pdf/2510.04746

• Abstract
  Massive stars exhibit a perplexing mismatch between their inferred masses from different observational techniques, posing a significant challenge to our understanding of stellar evolution and structure. This discrepancy is believed to be caused by the underestimation of the convective core masses. The efficiency of such measurement is usually impaired by a lot of processes at work in the interior of the stars such as convective core overshooting and interior rotation. By integrating the precision of asteroseismology which provides insights into the internal structure and dynamics of stars, with the detailed observational constraints offered by eclipsing binary systems, this study aims to precisely characterize a sample of massive stars in eclipsing binaries to infer their properties and evolutionary state. In this paper, the sample, observed photometrically with TESS and spectroscopically with SALT HRS, CHIRON, HERMES and a spectrograph at Skalnate Pleso Observatory between 2021 and 2024, are analyzed. The orbital elements as well as the basic stellar parameters of the targets in the sample are fitted to derive the geometry of their orbits as well as their absolute parameters. The asteroseismic properties of the targets are also obtained, which unravel their core dynamics and profiles. This is a precursor work that provides detailed characterization of the targets in the sample for future theoretical modeling.

Heat Reveals What Clouds Conceal: Global Carbon & Longitudinally Asymmetric Chemistry on LTT 9779 b

• Authors: Reza Ashtari, Sean Collins, Jared Splinter, Kevin B. Stevenson, Vivien Parmentier, Jonathan Brande, Suman Saha, Sarah Stamer, Ian J. M. Crossfield, James S. Jenkins, K. Angelique Kahle, Joshua D. Lothringer, Nishil Mehta, Nicolas B. Cowan, Diana Dragomir, Laura Kreidberg, Thomas M. Evans-Soma, Tansu Daylan, Olivia Venot, Xi Zhang

• Subjects: Subjects:
  Earth and Planetary Astrophysics (astro-ph.EP)

• Arxiv link: https://arxiv.org/abs/2510.04863

• Pdf link: https://arxiv.org/pdf/2510.04863

• Abstract
  LTT-9779 b is an ultra-hot Neptune (Rp ~ 4.7 Re, Mp ~ 29 Me) orbiting its Sun-like host star in just 19 hours, placing it deep within the "hot Neptune desert," where Neptunian planets are seldom found. We present new JWST NIRSpec G395H phase-curve observations that probe its atmospheric composition in unprecedented detail. At near-infrared wavelengths, which penetrate the high-altitude clouds inferred from previous NIRISS/SOSS spectra, thermal emission reveals a carbon-rich atmosphere with opacity dominated by carbon monoxide (CO) and carbon dioxide (CO2). Both species are detected at all orbital phases, with retrieved mixing ratios of 10^-1 for CO and 10^-4 for CO2, indicating a globally well-mixed reservoir of carbon-bearing gases. We also moderately detect water vapor (H2O) and tentatively detect sulfur dioxide (SO2), providing insight into its chemistry and possible photochemical production under intense stellar irradiation. From these detections we infer a carbon-to-oxygen ratio near unity (C/O ~ 1) and a metallicity exceeding 500X Solar, consistent with equilibrium chemistry predictions for high-temperature atmospheres. This enrichment raises the mean molecular weight, reducing atmospheric escape, and likely helps LTT-9779 b retain a substantial atmosphere despite extreme irradiation. Our findings show that LTT-9779 b survives where few planets can, maintaining a carbon-rich atmosphere in a region where hot Neptune-class worlds are expected to evaporate. This makes LTT-9779 b a valuable laboratory for studying atmospheric escape and chemical processes under extreme conditions, offering new insight into the survival of planets in the hot Neptune desert.

The demographics of core-collapse supernovae I. The role of binary evolution and CSM interaction

• Authors: Andrea Ercolino, Harim Jin, Norbert Langer, Avishay Gal-Yam, Abel Schootemeijer, Caroline Mannes

• Subjects: Subjects:
  Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2510.04872

• Pdf link: https://arxiv.org/pdf/2510.04872

• Abstract
  The observational properties of core-collapse supernovae (CC-SNe) are shaped by the envelopes of their progenitors. In massive binary systems, mass-transfer alters the pre-SN structures compared to single stars, leading to a diversity in SN explosions. Aims. We compute the distribution of CC-SN properties based on comprehensive detailed grids of single and binary stellar evolution models. We conduct a grid-based population synthesis to produce a synthetic population of CC-SNe, and compare it to observed SN samples. We also apply various explodability and merger criteria to our models. In line with earlier results, we identify interacting SN progenitors as those stars that undergo CC during or shortly after a Roche-lobe overflow phase. With an interacting binary fraction of 68%, our models predict two-thirds of all CC-SNe to be of Type IIP/L, and 1/3 of Type Ibc, in agreement with recent volume-limited SN surveys. We find that 76% of the Type Ibc SN progenitors took part in a previous binary mass transfer (mostly as mass donor), but also 63% of the Type IIP/L SN progenitors (mostly as mass gainers), yielding a much broader envelope mass distribution than expected from single stars. We find that mass-transfer induced interacting SNe make up ~5% of all CC-SNe, which is close to the observed fractions of Type IIn and Type Ibn SNe. When assuming a disk or toroidal CSM geometry for Type IIn SNe, our models predict a bimodal distribution of the radiated energies, similar to that deduced from observations. While we find the effect of binary evolution on the relative number of Type Ibc and Type IIP/L SNe to be moderate, it leads to lower average ejecta masses in Type Ibc and Type IIb SNe, and can lead to higher pre-SN masses in Type IIP/L SNe than single stars. Binary models are also able to reproduce the number and properties of interacting SNe.

Physical interpretation of the oscillation spectrum on the RGB and AGB

• Authors: G. Dréau, Y. Lebreton, B. Mosser, D. Stello

• Subjects: Subjects:
  Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2510.04955

• Pdf link: https://arxiv.org/pdf/2510.04955

• Abstract
  The high-frequency resolution of the four-year $\textit{Kepler}$ time series allows detailed study of seismic modes in luminous giants. Seismic observables help infer interior structures via comparisons with stellar models. We aim to investigate differences between H-shell (Red-Giant Branch; RGB) and He-burning (red clump and Asymptotic-Giant Branch; AGB) stars in the He-II ionisation zone and the sensitivity of seismic parameters to input physics in stellar models. We used a grid of stellar models with masses $0.8-2.5M_\odot$ and metallicities $-1.0-0.25$dex, including mass loss, overshooting, thermohaline mixing, and rotation-induced mixing. P-mode frequencies were inferred by suppressing g-modes in the core. The main factors affecting seismic observables are stellar mass and metallicity. The He-II glitch amplitude in the local large frequency separation $\Delta\nu$ correlates with the He-II ionisation zone density, explaining observed differences between RGB and clump/AGB stars. That amplitude exceeds 10% of $\Delta\nu$ in high-luminosity giants, making the asymptotic expansion less accurate when $\Delta\nu \le 0.5,\mu$Hz. Mass loss on the RGB and rotation-induced mixing from the main sequence to the early-AGB produce phase differences in the He-II glitch modulation signature between RGB and clump/AGB stars. Efficient RGB mass loss (for $M \le 1.5,M_\odot$) and mixing processes (for $M \ge 1.5,M_\odot$) leave detectable signatures in p-mode frequencies, enabling classification of red giants.

A Link Between Rocky Planet Density and Host Star Chemistry

• Authors: Aida Behmard, Casey L. Brinkman, Soichiro Hattori, Ryan A. Rubenzahl, Megan Bedell

• Subjects: Subjects:
  Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2510.04981

• Pdf link: https://arxiv.org/pdf/2510.04981

• Abstract
  Planets and their host stars form from the same cloud of gas and dust, so we assume that their chemical compositions are linked. However, a clear correlation between rocky planet interior properties and host star chemistry remains elusive for planets around FGK dwarfs, and non-existent for planets around M dwarfs because cool stars frequently lack detailed chemical information. Here, we investigate the relationship between small (R${P}$ $\leq$ 1.8 R${\oplus}$) planet densities and host star elemental abundances. We use the Sloan Digital Sky Survey-V/Milky Way Mapper and an accompanying data-driven framework to obtain abundances for FGK and M dwarf hosts of 22 rocky planets. We find that planet densities exhibit a strong, inverse relationship to [Mg/Fe] abundances of FGK hosts (p = 0.001). This correlation becomes more significant with the addition of M dwarf hosts (p = 0.0005). If we assume that rocky planets have terrestrial-like compositions, this suggests that low [Mg/Fe] environments form planets with larger Fe-rich cores and thus higher densities. The thick disk planets in our sample help anchor this trend, illustrating the importance of sampling exoplanet properties across a range of host star populations. This finding highlights the connection between Galactic chemical evolution and rocky planet formation, and indicates that Earth-like planet compositions may vary significantly across different regions of the Galaxy.

Large Language Models Achieve Gold Medal Performance at International Astronomy & Astrophysics Olympiad

• Authors: Lucas Carrit Delgado Pinheiro, Ziru Chen, Bruno Caixeta Piazza, Ness Shroff, Yingbin Liang, Yuan-Sen Ting, Huan Sun

• Subjects: Subjects:
  Instrumentation and Methods for Astrophysics (astro-ph.IM); Artificial Intelligence (cs.AI); Computation and Language (cs.CL)

• Arxiv link: https://arxiv.org/abs/2510.05016

• Pdf link: https://arxiv.org/pdf/2510.05016

• Abstract
  While task-specific demonstrations show early success in applying large language models (LLMs) to automate some astronomical research tasks, they only provide incomplete views of all necessary capabilities in solving astronomy problems, calling for more thorough understanding of LLMs' strengths and limitations. So far, existing benchmarks and evaluations focus on simple question-answering that primarily tests astronomical knowledge and fails to evaluate the complex reasoning required for real-world research in the discipline. Here, we address this gap by systematically benchmarking five state-of-the-art LLMs on the International Olympiad on Astronomy and Astrophysics (IOAA) exams, which are designed to examine deep conceptual understanding, multi-step derivations, and multimodal analysis. With average scores of 85.6% and 84.2%, Gemini 2.5 Pro and GPT-5 (the two top-performing models) not only achieve gold medal level performance but also rank in the top two among ~200-300 participants in all four IOAA theory exams evaluated (2022-2025). In comparison, results on the data analysis exams show more divergence. GPT-5 still excels in the exams with an 88.5% average score, ranking top 10 among the participants in the four most recent IOAAs, while other models' performances drop to 48-76%. Furthermore, our in-depth error analysis underscores conceptual reasoning, geometric reasoning, and spatial visualization (52-79% accuracy) as consistent weaknesses among all LLMs. Hence, although LLMs approach peak human performance in theory exams, critical gaps must be addressed before they can serve as autonomous research agents in astronomy.

Exploring Low-Amplitude Variability in First Overtone Cepheids with TESS

• Authors: E. Plachy, H. Netzel, A. Bódi

• Subjects: Subjects:
  Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2510.05017

• Pdf link: https://arxiv.org/pdf/2510.05017

• Abstract
  Classical Cepheid stars that pulsate in the first overtone radial mode often exhibit additional periodicities at the millimagnitude level. Extensive studies of the OGLE data of the Magellanic Clouds have revealed distinct groups based on their period ratio with the first overtone mode. These groups are similar to those found in overtone RR Lyrae stars. Theoretical calculations suggest that some of the observed periodicities may be consistent with non-radial modes, while others remain unexplained. Currently, we only know of a handful of examples from the Galactic Cepheid sample that exhibit low-amplitude periodicities. The purpose of this study is to undertake a systematic search for low-amplitude variability in overtone Cepheids of the Milky Way in the photometric data of the full-frame images of the Transiting Exoplanet Survey Satellite, which were produced with the MIT Quick Look Pipeline. We applied standard Fourier analysis and classified the additional signals according to their period ratio to the overtone pulsation period. We found 127 stars in total to exhibit additional periodicities. In 17 stars, these can be identified as a second radial overtone. A further 83 stars were observed to display periodic signals with a ratio of $P_{\mathrm{x}}/P_{1\mathrm{O}}$ in the range 0.60$-$0.65. In 15 stars, the $P_{1\mathrm{O}}/P_{\mathrm{x}}$ is found to be near $\sim$0.68, of which six are also found to be in the previous group. Furthermore, we observed the presence of low-amplitude signals in 22 stars outside the aforementioned period ratios. It is possible that some of these may be direct detections of non-radial modes, with no harmonic frequency peak in the 0.60$-$0.65 period range. The TESS measurements revealed that the amplitudes and frequencies of these signals often vary within a TESS sector, a phenomenon that challenges theoretical models.

Spectral Properties of Anomalous Microwave Emission in 144 Galactic Clouds

• Authors: Roke Cepeda-Arroita, J. A. Rubiño-Martín, R. T. Génova-Santos, C. Dickinson, S. E. Harper, F. Poidevin, M. W. Peel, R. Rebolo, D. Adak, A. Almeida, K. Aryan, R. B. Barreiro, F. J. Casas, J. M. Casas, J. Chluba, M. Fernández-Torreiro, D. Herranz, G. A. Hoerning, Michael E. Jones, J. Leech, E. Martínez-González, T. J. Pearson, Angela C. Taylor, P. Vielva, R. A. Watson, Z. Zhang

• Subjects: Subjects:
  Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

• Arxiv link: https://arxiv.org/abs/2510.05067

• Pdf link: https://arxiv.org/pdf/2510.05067

• Abstract
  Anomalous Microwave Emission (AME) is a diffuse microwave component thought to arise from spinning dust grains, yet remains poorly understood. We analyze AME in 144 Galactic clouds by combining low-frequency maps from S-PASS (2.3 GHz), C-BASS (4.76 GHz), and QUIJOTE (10-20 GHz) with 21 ancillary maps. Using aperture photometry and parametric SED fitting via MCMC methods without informative priors, we measure AME emissivity, peak frequency, and spectral width. We achieve peak frequency constraints nearly three times tighter than previous work and identify 83 new AME sources. AME spectra are generally broader than predicted by spinning dust models for a single phase of the interstellar medium, suggesting either multiple spinning dust components along the line of sight or incomplete representation of the grain size distribution in current models. However, the narrowest observed widths match theoretical predictions, supporting the spinning dust hypothesis. The AME amplitude correlates most strongly with the thermal dust peak flux and radiance, showing $\sim30$% scatter and sublinear scaling, which suggests reduced AME efficiency in regions with brighter thermal dust emission. AME peak frequency increases with thermal dust temperature in a trend current theoretical models do not reproduce, indicating that spinning dust models must incorporate dust evolution and radiative transfer in a self-consistent framework where environmental parameters and grain properties are interdependent. PAH tracers correlate with AME emissivity, supporting a physical link to small dust grains. Finally, a log-Gaussian function provides a good empirical description of the AME spectrum across the sample, given current data quality and frequency coverage.

From theory to observation: understanding filamentary flows in high-mass star-forming clusters

• Authors: M. R. A. Wells, R. Pillsworth, H. Beuther, R. E. Pudritz, E. W. Koch

• Subjects: Subjects:
  Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

• Arxiv link: https://arxiv.org/abs/2510.05101

• Pdf link: https://arxiv.org/pdf/2510.05101

• Abstract
  Here we use data from multi-scale galactic MHD simulations to observe filaments and star forming clumps on 10's of pc scales and investigate flow rate relationships along, and onto filaments as well as flows towards the clumps. Using the FilFinderPPV identification technique, we identify the prominent filamentary structures in each data cube. Each filament and its corresponding clump are analysed by calculating flow rates along each filament towards the clump, onto each filament from increasing distances, and radially around each clump. This analysis is conducted for two cubes, one feedback dominated region, and one with less feedback. Looking at the face-on inclination of the simulations (0 degrees), we observe different trends depending on the environmental conditions (more or less feedback). The median flow rate in the region with more feedback is 8.9$\times$10$^{-5}$ M${sun}\mathrm{yr}^{-1}$ and we see that flow rates along the filaments toward the clumps generally decrease in these regions. In the region with less feedback we have a median flow rate of 2.9$\times$10$^{-4}$ M${sun}\mathrm{yr}^{-1}$ and when looking along the filaments here we see the values either increase or remain constant. We find that the flow rates from the environments onto the primary filaments are of an order of magnitude sufficient to sustain the flow rates along these filaments. When discussing the effects of galactic and filamentary inclination, we also observe that viewing the filaments from different galactic inclinations can reveal the presence of feeder structures (smaller filamentary structures aiding in the flow of material). The method used to estimate these flow rates, which has been previously applied to observational data, produced results consistent with those obtained from the simulations themselves, providing high confidence in the flow rate calculation method.

by olozhika (Xing Yuchen).

2025-10-07