Showing new listings for Thursday, 2 October 2025

[olozhika]

Showing new listings for Thursday, 2 October 2025

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

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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: 14papers

AstroMMBench: A Benchmark for Evaluating Multimodal Large Language Models Capabilities in Astronomy

• Authors: Jinghang Shi, Xiao Yu Tang, Yang Hunag, Yuyang Li, Xiaokong, Yanxia Zhang, Caizhan Yue

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

• Arxiv link: https://arxiv.org/abs/2510.00063

• Pdf link: https://arxiv.org/pdf/2510.00063

• Abstract
  Astronomical image interpretation presents a significant challenge for applying multimodal large language models (MLLMs) to specialized scientific tasks. Existing benchmarks focus on general multimodal capabilities but fail to capture the complexity of astronomical data. To bridge this gap, we introduce AstroMMBench, the first comprehensive benchmark designed to evaluate MLLMs in astronomical image understanding. AstroMMBench comprises 621 multiple-choice questions across six astrophysical subfields, curated and reviewed by 15 domain experts for quality and relevance. We conducted an extensive evaluation of 25 diverse MLLMs, including 22 open-source and 3 closed-source models, using AstroMMBench. The results show that Ovis2-34B achieved the highest overall accuracy (70.5%), demonstrating leading capabilities even compared to strong closed-source models. Performance showed variations across the six astrophysical subfields, proving particularly challenging in domains like cosmology and high-energy astrophysics, while models performed relatively better in others, such as instrumentation and solar astrophysics. These findings underscore the vital role of domain-specific benchmarks like AstroMMBench in critically evaluating MLLM performance and guiding their targeted development for scientific applications. AstroMMBench provides a foundational resource and a dynamic tool to catalyze advancements at the intersection of AI and astronomy.

The warm outer layer of a Little Red Dot as the source of [Fe II] and collisional Balmer lines with scattering wings

• Authors: Alberto Torralba, Jorryt Matthee, Gabriele Pezzulli, Rohan P. Naidu, Yuzo Ishikawa, Gabriel B. Brammer, Seok-Jun Chang, John Chisholm, Anna de Graaff, Francesco D'Eugenio, Claudia Di Cesare, Anna-Christina Eilers, Jenny E. Greene, Max Gronke, Edoardo Iani, Vasily Kokorev, Gauri Kotiwale, Ivan Kramarenko, Yilun Ma, Sara Mascia, Benjamín Navarrete, Erica Nelson, Pascal Oesch, Robert A. Simcoe, Stijn Wuyts

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

• Arxiv link: https://arxiv.org/abs/2510.00103

• Pdf link: https://arxiv.org/pdf/2510.00103

• Abstract
  The population of the Little Red Dots (LRDs) may represent a key phase of supermassive black hole (SMBH) growth. A cocoon of dense excited gas is emerging as key component to explain the most striking properties of LRDs, such as strong Balmer breaks and Balmer absorption, as well as the weak IR emission. To dissect the structure of LRDs, we analyze new deep JWST/NIRSpec PRISM and G395H spectra of FRESCO-GN-9771, one of the most luminous known LRDs at $z=5.5$. These reveal a strong Balmer break, broad Balmer lines and very narrow [O III] emission. We unveil a forest of optical [Fe II] lines, which we argue is emerging from a dense ($n_{\rm H}=10^{9-10}$ cm$^{-3}$) warm layer with electron temperature $T_{\rm e}\approx7000$ K. The broad wings of H$\alpha$ and H$\beta$ have an exponential profile due to electron scattering in this same layer. The high $\rm H\alpha:H\beta:H\gamma$ flux ratio of $\approx10.4:1:0.14$ is an indicator of collisional excitation and resonant scattering dominating the Balmer line emission. A narrow H$\gamma$ component, unseen in the other two Balmer lines due to outshining by the broad components, could trace the ISM of a normal host galaxy with a star formation rate $\sim5$ M${\odot}$ yr$^{-1}$. The warm layer is mostly opaque to Balmer transitions, producing a characteristic P-Cygni profile in the line centers suggesting outflowing motions. This same layer is responsible for shaping the Balmer break. The broad-band spectrum can be reasonably matched by a simple photoionized slab model that dominates the $\lambda>1500$ Å continuum and a low mass ($\sim10^8$ M${\odot}$) galaxy that could explain the narrow [O III], with only subdominant contribution to the UV continuum. Our findings indicate that Balmer lines are not directly tracing gas kinematics near the SMBH and that the BH mass scale is likely much lower than virial indicators suggest.

SN 2025coe: A Triple-Peaked Calcium-Strong Transient from A White-Dwarf Progenitor

• Authors: Chun Chen, Ning-Chen Sun, Qiang Xi, Samaporn Tinyanont, David Aguado, Ismael Pérez-Fournon, Frédérick Poidevin, Justyn R. Maund, Amit Kumar, Junjie Jin, Yiming Mao, Beichuan Wang, Yu Zhang, Zhen Guo, Wenxiong Li, César Rojas-Bravo, Rong-Feng Shen, Lingzhi Wang, Ziyang Wang, Guoying Zhao, Jie Zheng, Yinan Zhu, David López Fernández-Nespral, Alicia López-Oramas, Zexi Niu, Yanan Wang, Klaas Wiersema, Jifeng Liu

• Subjects: Subjects:
  High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Phenomenology (hep-ph)

• Arxiv link: https://arxiv.org/abs/2510.00135

• Pdf link: https://arxiv.org/pdf/2510.00135

• Abstract
  SN 2025coe is a calcium-strong transient located at an extremely large projected offset $\sim$39.3 kpc from the center of its host, the nearby early-type galaxy NGC 3277 at a distance of $\sim$25.5 Mpc. In this paper, we present multi-band photometric and spectroscopic observations spanning $\sim$100 days post-discovery. Its multi-band light curves display three distinct peaks: (1) an initial peak at $t \approx 1.6$ days attributed to shock cooling emission, (2) a secondary peak of $M_{R, , peak} \approx$ $-$15.8 mag at $t \approx 10.2$ days powered by radioactive decay, and (3) a late-time bump at $t \approx 42.8$ days likely caused by ejecta-circumstellar material/clump interaction. Spectral evolution of SN 2025coe reveals a fast transition to the nebular phase within 2 months, where it exhibits an exceptionally high [Ca II]/[O I] ratio larger than 6. Modeling of the bolometric light curve suggests an ejecta mass of $M_{\rm ej} = 0.29^{+0.14}{-0.15} , M{\odot}$, a $^{56}$Ni mass of $M_{\rm ^{56}Ni} = 2.4^{+0.06}{-0.05} \times 10^{-2} M{\odot}$, and a progenitor envelope with mass $M_e = 1.4^{+6.9}{-1.2} \times 10^{-3} , M{\odot}$ and radius $R_e = 13.5^{+64.1}{-11.1} , R{\odot}$. The tidal disruption of a hybrid HeCO white dwarf (WD) by a low-mass CO WD provides a natural explanation for the low ejecta mass, the small fraction of $^{56}$Ni, and the presence of an extended, low-mass envelope.

Icy or Rocky? Convective or Stable? New interior models of Uranus and Neptune

• Authors: Luca Morf, Ravit Helled

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

• Arxiv link: https://arxiv.org/abs/2510.00175

• Pdf link: https://arxiv.org/pdf/2510.00175

• Abstract
  We present a new framework for constructing agnostic and yet physical models for planetary interiors and apply it to Uranus and Neptune. Unlike previous research that either impose rigid assumptions or rely on simplified empirical profiles, our approach bridges both paradigms. Starting from randomly generated density profiles, we apply an iterative algorithm that converges toward models that simultaneously satisfy hydrostatic equilibrium, match the observed gravitational moments, and remain thermodynamically and compositionally consistent. The inferred interior models for Uranus and Neptune span a wide range of possible interior structures, in particular encompassing both water-dominated and rock-dominated configurations (rock-to-water mass ratios between 0.04-3.92 for Uranus and 0.20-1.78 for Neptune). All models contain convective regions with ionic water and have temperature-pressure profiles that remain above the demixing curves for hydrogen-helium-water mixtures. This offers both a plausible explanation for the observed non-dipolar magnetic fields and indicates that no hydrogen-helium-water demixing occurs. We find a higher H-He mass fraction in the outermost convection zones for Uranus (0.62-0.73) compared to Neptune (0.25-0.49) and that Uranus' magnetic field is likely generated deeper in the interior compared to Neptune. We infer upper limits of 0.69-0.74 (Uranus) vs. 0.78-0.92 (Neptune) for the outer edges of the dynamo regions in units of normalised radii. Overall, our findings challenge the conventional classification of Uranus and Neptune as "ice giants" and underscore the need for improved observational data or formation constraints to break compositional degeneracy.

Searching for Ultra-light Dark Matter in Spatial Correlations of White Dwarf Structure

• Authors: Nicole R. Crumpler, Nadia L. Zakamska, Gautham Adamane Pallathadka, Kareem El-Badry

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

• Arxiv link: https://arxiv.org/abs/2510.00271

• Pdf link: https://arxiv.org/pdf/2510.00271

• Abstract
  If dark matter is ultra-light and has certain Standard Model interactions, it can change the mass-radius relation of white dwarf stars. The coherence length of ultra-light dark matter imparts spatial correlations in deviations from the canonical mass-radius relation, and thus white dwarfs can be used to reconstruct the coherence length, or equivalently the particle mass, of the dark matter field. We simulate the observability of such spatial correlations accounting for realistic complications like variable hydrogen envelope thickness, dust, binaries, measurement noise, and distance uncertainties in DA white dwarfs. Using a machine learning approach on simulated data, we measure the dark matter field coherence length and find that large deviations from the mass-radius relation ($\sim10%$ change in radius) are needed to produce an observable signal given realistic noise sources. We apply our spatial correlation measurement routine to the SDSS catalog of 10,207 DA white dwarfs. We detect a positive spatial correlation among white dwarfs at separations corresponding to a coherence length of $300\pm50$ pc, with an average Z-score of 85 for white dwarfs separated by less than this coherence length. We conclude that this signal is due to observational bias. The signal can be explained by an offset between measurements and theory for nearby cool white dwarfs, and the presence of few, low-temperature white dwarfs with noisy measurements at further distances. With future improvements in white dwarf models and measurement techniques, particularly for cool white dwarfs, this method can provide interesting constraints on ultra-light dark matter models.

The Colors of Ices: Measuring ice column density through photometry

• Authors: Adam Ginsburg, Savannah R. Gramze, Matthew L. N. Ashby, Brandt A. L. Gaches, Nazar Budaiev, Miriam G. Santa-Maria, Alyssa Bulatek, A. T. Barnes, Desmond Jeff, Neal J. Evans II, Cara D. Battersby

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

• Arxiv link: https://arxiv.org/abs/2510.00292

• Pdf link: https://arxiv.org/pdf/2510.00292

• Abstract
  Ices imprint strong absorption features in the near- and mid-infrared, but until recently they have been studied almost exclusively with spectroscopy toward small samples of bright sources. We show that JWST photometry alone can reveal and quantify interstellar ices and present a new open-source modeling tool, icemodels, to produce synthetic photometry of ices based on laboratory measurements. We provide reference tables indicating which filters are likely to be observably affected by ice absorption. Applying these models to NIRCam data of background stars behind Galactic Center (GC) clouds, and validating against NIRSpec spectra of Galactic disk sources, we find clear signatures of CO, H$_2$O, and CO$_2$ ices and evidence for excess absorption in the F356W filter likely caused by CH-bearing species such as methanol. The ice ratios differ between the Galactic disk and Center, with GC clouds showing a higher H$2$O fraction. The large ice abundance in CO, H2O, and possibly complex molecules hints that the high complex molecule abundances observed in gas emission in the CMZ are driven by ice-phase chemistry in non-star-forming gas. Accounting for all likely ices, we infer that $>25%$ of the total carbon is frozen into CO ice in the GC, which exceeds the entire solar-neighborhood carbon budget. By assuming the freezeout fraction is the same in GC and disk clouds, we obtain a metallicity measurement indicating that $Z_GC\gtrsim2.5Z\odot$. These results demonstrate that photometric ice measurements are feasible with JWST and capable of probing the metallicity structure of the cold interstellar medium.

oMEGACat. VII. Tracing Interstellar and Intracluster Medium of $ω$ Centauri using Sodium Absorptions

• Authors: Z. Wang (Purmortal), A. C. Seth, M. Latour, J. Strader, M. Häberle, N. Neumayer, C. Clontz, S. Kamann, M. S. Nitschai, M. Alfaro-Cuello, A. Bellini, A. Feldmeier-Krause, M. Libralato, A. P. Milone, P. J. Smith, S. O. Souza, G. van de Ven

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

• Arxiv link: https://arxiv.org/abs/2510.00330

• Pdf link: https://arxiv.org/pdf/2510.00330

• Abstract
  We investigate the foreground interstellar medium along the line of sight and intracluster medium of $\omega$ Centauri ($\omega$ Cen) by measuring the equivalent width of Na I D absorptions from MUSE observations. The large line-of-sight velocity difference between $\omega$ Cen and the foreground enables us to separate Na I D absorption contributed from atomic gas in the interstellar and intracluster medium. We find that small-scale substructures in the foreground Na I D distribution correlate with differential reddening derived from photometric methods. Using an empirical Na I D equivalent width-reddening relation, we determine an average reddening of $E(B-V)=0.153\pm0.003$ mag within the half-light radius of $\omega$ Cen. However, the Na I D-inferred differential reddening is significantly larger than photometric estimates. This is likely due to scatter in the Na I D-reddening relation. We find no evidence for intracluster atomic gas from spectra of horizontal branch stars, as there is no significant Na I D absorption at $\omega$ Cen's systemic velocity. Given this non-detection, we place the strongest upper limit to date on the intracluster atomic gas column density in $\omega$ Cen of $\lesssim2.17 \times 10^{18}~\rm{cm^{-2}}$. We also estimate the ionized gas density from pulsar dispersion measure variations, which exceed the atomic gas limit by $\sim$50 times. Nevertheless, the strong correlation between dispersion measure and foreground Na I D suggests that much or all of this ionized gas resides in the foreground. Given ongoing mass loss from bright giant stars, our findings imply that the intracluster gas accumulation timescale is short, and gas removal in the cluster is likely not tied to stripping as $\omega$ Cen passes through the Galactic disk.

Kinematic analysis of an Ultra-Strong MgII absorber at z~1.13 linking to Circumgalactic Gas Structures

• Authors: Purvi Udhwani, Sameer, Anand Narayanan, Sowgat Muzahid, Jane Charlton, Sebastiano Cantalupo

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

• Arxiv link: https://arxiv.org/abs/2510.00729

• Pdf link: https://arxiv.org/pdf/2510.00729

• Abstract
  We present a spectroscopic and imaging analysis of the $z_{gal} \approx 1.1334$ ultra-strong MgII absorption system identified in the $VLT$/UVES spectrum of a background quasar located at $\rho \approx 18$ kpc from a star-forming galaxy. Low ionization metal lines like MgI, FeII, and CaII are also detected for this absorber. The HI lines are outside of the wavelength coverage. The MgII has a rest-frame equivalent width of $W_r(2796) =3.185 +/- 0.032 A^{\circ} $, with the absorption spread across $\Delta v \approx 460$ km~s$^{-1}$ in several components. A component-by-component ionization modeling shows several of these components having solar and higher metallicities. The models also predict a total HI column density of $log[N(HI)/cm^{-2}] \approx 22.5$, consistent with ultra-strong MgII absorbers being sub-Damped Lyman Alpha and Damped Lyman Alpha systems. The absorber is well within the virial radius of the nearest galaxy which has a stellar mass $M_* = 4.7 \times 10^{10}$~M$\odot$, and a star formation rate of $\approx 8.3$~M$\odot$~yr$^{-1}$. The absorption is along the projected major axis of the galaxy with a velocity spread that is wider than the galaxy's disk rotation. From the kinematic analysis of the absorber and the galaxy, the origin of the absorption can be attributed to a combination of circumgalactic gas structures, some corotating with the disk and the rest at line-of-sight velocities outside of the disk rotation.

The gas streamer G1-2-3 in the Galactic Center

• Authors: S. Gillessen, F. Eisenhauer, J. Cuadra, R. Genzel, D. Calderon, S. Joharle, T. Piran, D.C. Ribeiro, C.M.P. Russell, M. Sadun Bordoni, A. Burkert, G. Bourdarot, A. Drescher, F. Mang, T. Ott, G. Agapito, A. Agudo Berbel, A. Baruffolo, M. Bonaglia, M. Black, R. Briguglio, Y. Cao, L. Carbonaro, G. Cresci, Y. Dallilar, R. Davies, M. Deysenroth, I. Di Antonio, A. Di Cianno, G. Di Rico, D. Doelman, M. Dolci, S. Esposito, D. Fantinel, D. Ferruzzi, H. Feuchtgruber, N. M. Förster Schreiber, A. M. Glauser, P. Grani, M. Hartl, D. Henry, H. Huber, C. Keller, M. Kenworthy, K. Kravchenko, J. Lightfoot, D. Lunney, D. Lutz, M. Macintosh, F. Mannucci, D. Pearson, A. Puglisi, S. Rabien, C. Rau, A. Riccardi, B. Salasnich, T. Shimizu, F. Snik, E. Sturm, L. J. Tacconi, W. Taylor, A. Valentini, C. Waring, M. Xompero

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

• Arxiv link: https://arxiv.org/abs/2510.00897

• Pdf link: https://arxiv.org/pdf/2510.00897

• Abstract
  The black hole in the Galactic Center, Sgr A*, is prototypical for ultra-low-fed galactic nuclei. The discovery of a hand-full of gas clumps in the realm of a few Earth masses in its immediate vicinity provides a gas reservoir sufficient to power Sgr A*. In particular, the gas cloud G2 is of interest due to its extreme orbit, on which it passed at a pericenter distance of around 100 AU and notably lost kinetic energy during the fly-by due to the interaction with the black hole accretion flow. 13 years prior to G2, a resembling gas cloud called G1, passed Sgr A* on a similar orbit. The origin of G2 remained a topic of discussion, with models including a central (stellar) source still proposed as alternatives to pure gaseous clouds. Here, we report the orbit of a third gas clump moving again along (almost) the same orbital trace. Since the probability of finding three stars on close orbits is very small, this strongly argues against stellar-based source models. Instead, we show that the gas streamer G1-2-3 plausibly originates from the stellar wind of the massive binary star IRS16SW. This claim is substantiated by the fact that the small differences between the three orbits - the orientations of the orbital ellipses in their common plane as a function of time - are consistent with the orbital motion of IRS 16SW.

From atoms to stars: Modelling $\mathrm{H}_2$ formation and its impact on galactic evolution

• Authors: E. Lozano, C. Scannapieco, S.E. Nuza, Y. Ascasibar, V. Springel

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

• Arxiv link: https://arxiv.org/abs/2510.00959

• Pdf link: https://arxiv.org/pdf/2510.00959

• Abstract
  We present a sub-grid model for star formation in galaxy simulations, incorporating molecular hydrogen ($\mathrm{H}_2$) production via dust grain condensation and its destruction through star formation and photodissociation. Implemented within the magnetohydrodynamical code AREPO, our model tracks the non-equilibrium mass fractions of molecular, ionised, and atomic hydrogen, as well as a stellar component, by solving a system of differential equations governing mass exchange between these phases. Star formation is treated with a variable rate dependent on the local $\mathrm{H}_2$ abundance, which itself varies in a complex way with key quantities such as gas density and metallicity. Testing the model in a cosmological simulation of a Milky Way-mass galaxy, we obtain a well-defined spiral structure at $z = 0$, including a gas disc twice the size of the stellar one, alongside a realistic star formation history. Our results show a broad range of star formation efficiencies per free-fall time, from as low as $0.001%$ at high redshift to values between $0.1%$ and $10%$ for ages $\gtrsim 3-4 , \mathrm{Gyr}$. These findings align well with observational estimates and simulations of a turbulent interstellar medium. Notably, our model reproduces a star formation rate versus molecular hydrogen surface densities relation akin to the molecular Kennicutt-Schmidt law. Furthermore, we find that the star formation efficiency varies with density and metallicity, providing an alternative to fixed-efficiency assumptions and enabling comparisons with more detailed star formation models. Comparing different star formation prescriptions, we find that in models that link star formation to $\mathrm{H}_2$, star formation onset is $\sim ! 500 , \mathrm{Myr}$ later than those relying solely on total or cold gas density.

Powerful lightning on Venus constrained by atmospheric NO

• Authors: Tereza Constantinou, Oliver Shorttle, Paul B. Rimmer

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

• Arxiv link: https://arxiv.org/abs/2510.00973

• Pdf link: https://arxiv.org/pdf/2510.00973

• Abstract
  Signs of lightning on Venus have long been sought, including by space missions and ground-based telescopes searching for optical flashes, plasma waves, or radio signatures. These efforts have yielded conflicting findings regarding the presence or absence of lightning in Venus's atmosphere. In this study we adopt an indirect approach to constrain the prevalence of lightning on Venus, using the chemical by-products it produces in Venus's atmosphere. Nitric oxide (NO) is a key tracer species of lightning, being exclusively generated by lightning in Venus's lower atmosphere. By calculating the present rate of atmospheric destruction of NO in Venus's atmosphere through photochemical-kinetic modelling, we constrain the lightning power required to sustain the estimated NO abundances on modern Venus. The reported NO constraints require lightning to generate at-least three times the power released on Earth; consistent with either a higher rate of strikes, or greater energy per strike, or a combination of both. Limited detections of optical flashes within the clouds could point to lightning striking deeper in the atmosphere and nearer the surface -- with the result that its optical flashes are obscured by the clouds -- driven by triboelectric charging during volcanic eruptions or wind interactions with surface sediments. Our findings underscore the importance for future missions of confirming lightning on Venus, either by verifying the below-cloud NO abundance, or by detecting another unambiguous lightning signature, to provide the first definitive evidence of lightning on a rocky planet other than Earth.

Molecular Mobility of Extraterrestrial Ices: Surface Diffusion in Astrochemistry and Planetary Science

• Authors: N.F.W. Ligterink, C. Walsh, H.M. Cuppen, M.N. Drozdovskaya, A. Ahmad, D.M. Benoit, J.T. Carder, A. Das, J. K. Díaz-Berríos, F. Dulieu, J. Heyl, A.P. Jardine, T. Lamberts, N.M. Mikkelsen, M. Tsuge

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

• Arxiv link: https://arxiv.org/abs/2510.01018

• Pdf link: https://arxiv.org/pdf/2510.01018

• Abstract
  Molecules are ubiquitous in space. They are necessary component in the creation of habitable planetary systems and can provide the basic building blocks of life. Solid-state processes are pivotal in the formation of molecules in space and surface diffusion in particular is a key driver of chemistry in extraterrestrial environments, such as the massive clouds in which stars and planets are formed and the icy objects within our Solar System. However, for many atoms and molecules quantitative theoretical and experimental information on diffusion, such as activation barriers, are lacking. This hinders us in unraveling chemical processes in space and determining how the chemical ingredients of planets and life are formed. In this article, an astrochemical perspective on diffusion is provided. Described are the relevant adsorbate-surface systems, the methods to model their chemical processes, and the computational and laboratory techniques to determine diffusion parameters, including the latest developments in the field. While much progress has been made, many astrochemically relevant systems remain unexplored. The complexity of ice surfaces, their temperature-dependent restructuring, and effects at low temperatures create unique challenges that demand innovative experimental approaches and theoretical frameworks. This intersection of astrochemistry and surface science offers fertile ground for physical chemists to apply their expertise. We invite the physical chemistry community to explore these systems, where precise diffusion parameters would dramatically advance our understanding of molecular evolution in space - from interstellar clouds to planetary surfaces - with implications on our understanding on the origins of life and planetary habitability.

Carbon and nitrogen as indicators of stellar evolution and age. A homogeneous sample of 44 open clusters from the Gaia-ESO Survey

• Authors: G. Tautvaišienė, A. Drazdauskas, Š. Mikolaitis, R. Minkevičiūtė, E. Stonkutė, S. Randich, A. Bragaglia, L. Magrini, R. Smiljanic, M. Ambrosch, V. Bagdonas, G. Casali, Y. Chorniy, C. Viscasillas Vázquez

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

• Arxiv link: https://arxiv.org/abs/2510.01045

• Pdf link: https://arxiv.org/pdf/2510.01045

• Abstract
  Context. Low- and intermediate-mass giants undergo a complex chemical evolution that has yet to be observationally probed. The influence of core helium flash on the chemical composition of stellar atmospheres has been an open question since its theoretical prediction 60 years ago. Aims. Based on high-resolution spectral observations of 44 open star clusters in the Gaia-ESO survey, our aim is to perform the first large-scale homogeneous investigation into the carbon and nitrogen photospheric content of low- and intermediate-mass giant stars in different phases of evolution. Methods. We determined carbon and nitrogen abundances using spectral synthesis of the C2 Swan (1,0) band head at 5135 Å and C2 Swan (0,1) band head at 5635.5 Å, 12C14N bands in the interval 6470 - 6490 Å, and the forbidden [O i] line at 6300.31 Å. Results. We revealed differences in C/N abundance ratios between pre- and post-core-He-flash stars. The lower C/N ratios in core He-burning red clump stars are mainly due to the enhancement of nitrogen abundances. We presented calibrations of the relationship between [C/N] and stellar age for solar metallicity low- and intermediate-mass giants taking into account different evolutionary stages. Conclusions. The C/N abundance ratios in the investigated first-ascent giant stars are slightly less affected by the first dredge-up than predicted by the theoretical models. The rotation-induced extra mixing is not as efficient as theoretically predicted. The core helium flash may trigger additional alterations in carbon and nitrogen abundances that are not yet theoretically modelled. We found that the evolutionary stage of stars must be taken into account when using [C/N] as an age indicator.

Vanishing Acts: Quantifying Black Hole Formation with the DSNB Signal

• Authors: Tim Charissé, David Maksimović, George A. Parker, Michael Wurm

• Subjects: Subjects:
  High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph); Instrumentation and Detectors (physics.ins-det)

• Arxiv link: https://arxiv.org/abs/2510.01177

• Pdf link: https://arxiv.org/pdf/2510.01177

• Abstract
  The diffuse supernova neutrino background (DSNB) created by stellar core-collapses throughout cosmic history is on the verge of discovery, with SK-Gd showing early deviations from the background expectation and JUNO starting to take data. However, the interpretation of early DSNB data will face significant challenges due to degeneracies between astrophysical parameters and uncertainties in supernova neutrino modeling. We explore how complementary astronomical observations can break these degeneracies and, in this context, we investigate whether early DSNB observations can constrain invisible supernovae, which have no optical emission but are powerful neutrino sources before being swallowed by a forming black hole. Leveraging the differences in the spectra between invisible and visible supernovae, we estimate the sensitivity of 1) detecting the existence of invisible supernovae, and 2) determining the fraction of invisible supernovae. Finally, we discuss how these conclusions depend on the spectral parameters of the black hole-forming component.

by olozhika (Xing Yuchen).

2025-10-02