Showing new listings for Tuesday, 23 September 2025

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Showing new listings for Tuesday, 23 September 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: 21papers

Neutrinos from core-collapse supernovae

• Authors: Georg G. Raffelt (MPP), Hans-Thomas Janka (MPA), Damiano F. G. Fiorillo (DESY)

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

• Arxiv link: https://arxiv.org/abs/2509.16306

• Pdf link: https://arxiv.org/pdf/2509.16306

• Abstract
  The core of a massive star (M > 8 Msun) eventually collapses. This implosion usually triggers a supernova (SN) explosion that ejects most of the stellar envelope and leaves behind a neutron star (NS) with a mass of up to about 2 Msun. Sometimes the explosion fails and a black hole forms instead. The NS radiates its immense binding energy (some 10% of its rest mass or $2-4\times10^{53}$ erg) almost entirely as neutrinos and antineutrinos of all flavors with typical energies of some 10 MeV. This makes core-collapse SNe the most powerful neutrino factories in the Universe. Such a signal was observed once - with limited statistics - from SN 1987A in the Large Magellanic Cloud. Today, however, many large neutrino detectors act as SN observatories and would register a high-statistics signal. A future Galactic SN, though rare (1-3 per century), would produce a wealth of astrophysical and particle-physics information, including possible signatures for new particles. Neutrinos are key to SN dynamics in the framework of the Bethe-Wilson delayed explosion paradigm. After collapse, they are trapped in the core for a few seconds, forming a dense neutrino plasma that can exhibit collective flavor evolution caused by the weak interaction, a subject of intense theoretical research.

Simulated 3D $^{56}$Ni Distributions of Type IIp Supernovae

• Authors: David Vartanyan, Adam Burrows, Lizzy Teryoshin, Tianshu Wang, Daniel Kasen, Benny Tsang, Matthew S.B. Coleman

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

• Arxiv link: https://arxiv.org/abs/2509.16314

• Pdf link: https://arxiv.org/pdf/2509.16314

• Abstract
  We present the first three-dimensional study of the asymptotic ejecta distributions for a suite of theoretical Type IIp supernovae originating from red supergiant progenitors. We simulate using the radiation-hydrodynamic code F{\sc{ornax}} from core bounce through the first seconds of the neutrino-driven explosion and then follow using a hydrodynamic variant of the code FLASH until shock breakout of the star and through to homologous expansion of the ejecta into the circumstellar environment. Our studied progenitor models range from 9 to 25 M$_{\odot}$, with explosion energies spanning $\sim$0.1$-$1 Bethe. The shock breakout times span the range $\sim$1$-$4 days, with a breakout time spread by direction ranging from hours to over a day. We find that the dipole orientation of the $^{56}$Ni ejecta is well-preserved from the first seconds out to shock breakout. The $^{56}$Ni ejecta penetrates through the initially outer oxygen shell, and its global structure is imprinted with small-scale clumping as the ejecta evolve through the stellar envelope. For the majority of our models, the neutron star kick is anti-aligned with the $^{56}$Ni ejecta. Models with strongly dipolar ejecta morphology and a massive hydrogen/helium envelope with an inner boundary located deep see as much as $\sim$70% of the $^{56}$Ni ejecta mixed into that outer envelope, reaching asymptotic velocities ranging from $\sim$350 to 3200 km s$^{-1}$. Supernovae arising from red supergiant progenitors and exhibiting prominent nickel features generally display significant $^{56}$Ni mixing into the stellar envelope.

Polarized Signatures of Variable Worlds: Modeling Heterogeneous Habitable Earth- and Early Mars-like (Exo)planets

• Authors: Kenneth E. Goodis Gordon, Theodora Karalidi, Kimberly M. Bott, Connor J. Vancil, Maxwell A. Millar-Blanchaer, Nicholas F. Wogan, Eric T. Wolf

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

• Arxiv link: https://arxiv.org/abs/2509.16338

• Pdf link: https://arxiv.org/pdf/2509.16338

• Abstract
  Determining the habitability of terrestrial exoplanets is a complex problem that represents the next major step for the astrophysical community. The majority of current models treat these planets as homogeneous or contain heterogeneity that is constant in time. In reality, habitable exoplanets are expected to contain atmospheric and surface heterogeneities similar to Earth, with diurnal rotation, seasonal changes, and weather patterns resulting in complex, time-dependent signatures. Due to its ability to measure light as a vector, polarimetry provides an important tool that will enhance the characterizations of heterogeneous worlds. Here we model the visible to near-infrared linear spectropolarimetric signatures, as functions of wavelength and planetary phase angle, of various heterogeneous Earth scenarios as well as the first signals of an early wet and potentially habitable Mars. The contributions from the different atmospheric and surface properties result in asymmetric phase curves and variable spectra, with the polarization appearing to be more sensitive than flux to heterogeneities such as patchy clouds and continents moving into and out-of-view. Our models provide important predictions of expected polarized and unpolarized signatures of heterogeneous exoplanets that will help guide the designs and observing plans of future polarimeters, including those proposed for the upcoming Habitable Worlds Observatory.

Enhancing CTAO Monitoring and Alarm Subsystems in Distributed Environments Using ServiMon

• Authors: Kevin Munari, Alessandro Costa, Federico Incardona, Emilio Mastriani, Sebastiano Spinello, Stefano Germani, Pietro Bruno

• Subjects: Subjects:
  High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2509.16366

• Pdf link: https://arxiv.org/pdf/2509.16366

• Abstract
  ServiMon is a scalable data collection and auditing pipeline designed for service-oriented, cost-efficient quality control in distributed environments, including the CTAO monitoring, logging, and alarm subsystems. Developed within a Docker-based architecture, it leverages cloud-native technologies and distributed computing principles to enhance system observability and reliability. At its core, ServiMon integrates key technologies such as Prometheus, Grafana, Kafka, and Cassandra. Prometheus serves as the primary engine for real-time performance metric collection, enabling efficient monitoring across multiple nodes. Grafana provides interactive, service-oriented data visualization, facilitating system performance analysis. Additionally, Kafka and Cassandra expose system metrics via the JMX Exporter, offering critical insights into infrastructure availability and performance. This contribution exposes how ServiMon could provide an enhancement on scalability, security, and efficiency in a distributed computing environment, such as the CTAO monitoring, logging, and alarm subsystems. This integrated approach not only ensures robust real-time monitoring, but also optimizes operational costs. Furthermore, ServiMon's ability to generate large volumes of diverse data over time provides a strong foundation for predictive maintenance. By incorporating stochastic and approximate computing techniques, it enables proactive failure detection and system optimization, minimizing downtime and maximizing telescope availability.

Dark interactions in neutron star interiors: the interplay of baryons, dark matter, and dark energy

• Authors: L. F. Araujo, G. Lugones, J. A. S. Lima

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

• Arxiv link: https://arxiv.org/abs/2509.16484

• Pdf link: https://arxiv.org/pdf/2509.16484

• Abstract
  The impact of energy exchange among the relevant fluid components: baryonic matter, fermionic dark matter (DM), and dark energy (DE) on the internal structure of neutron stars is investigated. Using a representative DM mass $m_{\chi} = 10$ GeV and a barotropic DE relation, we add source terms Qi to the Tolman-Oppenheimer-Volkoff equations and examine three cases: (i) noninteracting fluids (Model I), (ii) fully interacting baryon plus DM and DM with DE fluids with optional DM self repulsion (Model II), and (iii) a unified dark sector coupled to baryons (Model III). Two effects dominate: softening by massive, pressure-poor DM, and additional softening/ and binding from DE with negative pressures. Model I isolates these baselines. In Model II, exchange terms self regulate, making the mass radius curves nearly independent of the coupling parameter $\alpha$ for nearly five orders of magnitude. Model III breaks this $\alpha$ degeneracy: a sizable vacuum fraction suppresses the baryonic pressure gradient, reducing both the maximum mass and radii, whereas a pure-DM core is less sensitive. We outline when dark interactions can leave observable, macroscopic imprints.

A New Subclass of Carbon-Enhanced Metal-Poor Stars at Extremely Low Metallicity

• Authors: Young Sun Lee, Timothy C. Beers, Yutaka Hirai, Jihye Hong, Miji Jeong, Changmin Kim, Young Kwang Kim

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

• Arxiv link: https://arxiv.org/abs/2509.16510

• Pdf link: https://arxiv.org/pdf/2509.16510

• Abstract
  We report the discovery of a new subclass of carbon-enhanced metal-poor (CEMP) stars, characterized by high absolute carbon abundances (A(C) > 7.39) and extremely low metallicity ([Fe/H] $<=$ -3.1) but notably lacking enhancements in neutron-capture elements, thus falling under the CEMP-no category. This population emerged from a detailed analysis of low-resolution spectroscopic data obtained from the Sloan Digital Sky Survey (SDSS) and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), where the observed frequency trends with the decreasing metallicity of CEMP-s (s-process-enhanced) and CEMP-no (no neutron-capture enhanced) stars deviated from established expectations. In contrast to earlier findings, we observe a rise in high-A(C) stars below [Fe/H] = -3.1, which we interpret as a distinct group not accounted for in traditional CEMP classifications. Following the Yoon-Beers group classification, we define these stars as Group IV. Statistical modeling confirms their presence as a separate peak in the A(C) distribution, and available radial velocity data suggest that about 30% of Group IV stars may be binaries, indicating possible binary-related formation mechanisms. This discovery challenges the current CEMP-no star formation pathways and implies the existence of alternative or hybrid enrichment scenarios in the early Universe. High-resolution spectroscopic follow-up of Group IV candidates will be crucial for identifying their progenitors and understanding their evolutionary implications.

Tracing ωCentauri's origins: Spatial and chemical signatures of its formation history

• Authors: E. Dondoglio, A. P. Milone, A. F. Marino, A. Mastrobuono-Battisti, E. Bortolan, M. V. Legnardi, T. Ziliotto, F. Muratore, G. Cordoni, E. P. Lagioia, M. Tailo

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

• Arxiv link: https://arxiv.org/abs/2509.16719

• Pdf link: https://arxiv.org/pdf/2509.16719

• Abstract
  \omega}Centauri ({\omega}Cen) is the most enigmatic Galactic globular cluster (GC), with unmatched chemical complexity. We combine photometric and spectroscopic catalogs to identify its distinct stellar populations and to investigate their spatial distribution and chemical properties, uncovering new insights into the cluster's formation history. We identify the iron-poor stars commonly found in GCs: the first population (1P), with halo-like chemical composition, and the second population (2P), enriched in elements produced by p-capture processes. Similarly, we divided the iron-rich stars (the anomalous stars) into two groups: the AI and the AII, exhibiting light-element abundance distributions similar to 1P and 2P stars, respectively. The wide extension of our dataset (five times the half-light radius) allowed us to directly and unambiguously compare the fraction of these populations at different radii. We find that 2P and AII stars are more centrally concentrated than the 1P and AI. The remarkable similarities between the 1P-2P and AI-AII radial distributions strongly suggest that these two groups of stars originated from similar mechanisms. Our chemical analysis indicates that the 1P and AI stars (the lower stream) developed their inhomogeneities through core-collapse supernova (and possibly other massive stars') self-enrichment, and that these populations contributed p-capture-processed material to the intracluster medium, from which the chemically extreme 2P and AII stars (the upper stream) formed. Additional polluters, such as intermediate-mass asymptotic giant branch stars and Type Ia supernovae, likely played a role in shaping the AII. Finally, we propose that 2P and AII stars with intermediate light-element abundances (the middle stream) formed via dilution between the pure ejecta that created the upper stream and lower-stream material.

GTC/OSIRIS Deep Spectroscopy of Galactic Compact Planetary Nebulae: PNG048.5+04.2 and PNG068.7+14.8

• Authors: Haomiao Huang, Xuan Fang, Letizia Stanghellini, Ting-Hui Lee, Martin A. Guerrero, Xiaohu Li, Richard Shaw, Jifeng Liu

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

• Arxiv link: https://arxiv.org/abs/2509.16885

• Pdf link: https://arxiv.org/pdf/2509.16885

• Abstract
  We report deep long-slit spectroscopy of two Galactic compact planetary nebulae (PNe), PNG048.5+04.2 and PNG068.7+14.8, obtained using the 10.4m Gran Telescopio Canarias (GTC). These spectra cover a broad wavelength range of ~3630-10370 A, enabling detection of numerous emission lines critical for nebular analysis, including [O II] 3727 and [O III] 4363 in the blue and [S III] 6312,9069 in the red. Also detected in the spectrum of PNG068.7+14.8 are broad C III and C IV lines probably due to stellar emission, indicating that the central star of this PN is [WC]-type. These GTC optical-IR spectra were analyzed in details in conjunction with the archival Spitzer/IRS mid-IR spectra, and elemental abundances of the two PNe determined. Photoionization models were established for the two PNe using CLOUDY, based on the ratios of line fluxes measured from the GTC optical-NIR spectra. Our best photoionization modeling, in combination with state-of-the-art post-AGB evolutionary model tracks, shows that both PNe evolved from low-mass progenitors (<2 M_sun) with relatively young ages (<3 Gyr), although their central cores are probably in different evolutionary stages - the central star of PNG068.7+14.8 is still in the process of heating up, while that of PNG048.5+04.2 has already entered the white dwarf cooling track. A comparison with AGB model predictions also constrains the progenitors of both PNe to be of low masses. Moreover, the two PNe are in line with the radial oxygen gradients exhibited by the Galactic PN populations, using the most up-to-date distances.

The Impact of ${}^{12} \mathrm{C}(α, γ)^{16} \mathrm{O}$ Reaction on the Evolution of He Stars

• Authors: Gang Long, Yu Wang, Dongdong Liu, Jianguo Wang, Bo Wang

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

• Arxiv link: https://arxiv.org/abs/2509.16948

• Pdf link: https://arxiv.org/pdf/2509.16948

• Abstract
  The ${}^{12} \mathrm{C}(\alpha, \gamma)^{16} \mathrm{O}$ reaction is one of the most important reactions in the evolution of massive stars, yet its rate is still highly uncertain. In this work, we investigated how variations in the ${}^{12} \mathrm{C}(\alpha, \gamma)^{16} \mathrm{O}$ reaction rate affect the evolution of a 14 $\rm M_{\odot}$ He star using the MESA code. Our simulations indicate that the ${}^{12} \mathrm{C}(\alpha, \gamma)^{16} \mathrm{O}$ reaction rate determines the conditions for C burning, affecting its explodability. As the reaction rate increases, central C-burning becomes neutrino-dominated, transitioning from the convective to the radiative regime. This leads to higher compactness and a larger iron core, indicating a more compact pre-SN core structure that is difficult to explode. Conversely, lower reaction rates shorten the C-burning lifetime and trigger earlier central Ne ignition, which counteracts core contraction. This results in reduced compactness and iron core mass. We also found that variations in reaction rates shift the location of the last C-burning shell. When this shell exceeds the mass coordinate used for compactness evaluation, the overall compactness increases significantly. Although the Si- and O-burning convective shells decrease compactness, the overall increase remains unaffected. This work suggests that the ${}^{12} \mathrm{C}(\alpha, \gamma)^{16} \mathrm{O}$ reaction play an important role in the pre-SN core structure and potentially impact the explodability of massive He stars.

On Atomic Line Opacities for Modeling Astrophysical Radiative Transfer

• Authors: Jonathan Morag

• Subjects: Subjects:
  High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2509.17003

• Pdf link: https://arxiv.org/pdf/2509.17003

• Abstract
  In astrophysics, line opacity is a primary source of uncertainty in theoretical calculations of radiative transfer. Much of this uncertainty is dominated by the inability to resolve the width and separation in frequency of sharp atomic transition lines, leading to the common use of approximate frequency-averaged treatments for the lines. In a previous paper, we calculated shock-cooling emission following explosions in core-collapse supernovae using a mult-group radiative transfer code, and compared the results to those of the similar and often used STELLA code from the literature. We found important differences in the spectral energy distribution (SED) resulting from different choices of line opacity treatment. In our code, we used in the emissivity a frequency-binned average of a high-resolution opacity, while in STELLA the often-used Eastman Pinto 1993 (EP93) prescription was employed. In this short letter we revisit this comparison, essentially reproducing STELLA bound-free (photoionization) and bound-bound (line transition) opacities. We show the importance of introducing micro-plasma electron excitation level cutoffs in the equation of state (EOS). We also argue that EP93 is useful for estimating photon mean free-path in the presence of a forest of lines, but that it can underestimate photon production and reprocessing rates (emissivity) by orders of magnitude. To our knowledge, no fully-consistent coarse-frequency solution currently exists for line modeling in these systems. Finally, we describe new features in our updated publicly available high-resolution frequency-dependent opacity table.

eROSITA-selection of new period-bounce Cataclysmic Variables: First follow-up confirmation using TESS and SDSS

• Authors: Daniela Muñoz-Giraldo, Beate Stelzer, Axel Schwope, Santiago Hernández-Díaz, Scott F. Anderson, Sebastian Demasi

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

• Arxiv link: https://arxiv.org/abs/2509.17216

• Pdf link: https://arxiv.org/pdf/2509.17216

• Abstract
  Between 40$%$ and 80$%$ of cataclysmic variables (CVs) are expected to have evolved past the period-minimum and contain a degenerate donor. However, observational surveys for CVs have only been able to detect a few of these highly evolved "period-bouncers", most likely due to the intrinsic faintness associated with their predicted low mass accretion rates. We have produced an initial selection of 137 high-likelihood period-bounce candidates from WD catalog based on our multiwavelength period-bouncer scorecard and selection cuts including X-ray data from the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spektrum-Roentgen-Gamma spacecraft (SRG). We have laid out three main requirements (classification as a CV, determination of an orbital period and detection of a very late-type donor) that should result in the confirmation of several of these candidates. Our path for confirming these candidates has already produced its first successful result with the confirmation of GALEX J125751.4-283015 as a new period-bouncer. Several other candidates have already fulfilled at least one of our three requirements making their future confirmation likely. Our search for period-bouncers using the X-ray eROSITA emission of objects in optical WD catalogs has led to the confirmation of six new period-bouncers identified from the Gaia DR3 WD catalog (five previously known CVs and one WD candidate), a 18$%$ increase that brings the present population to 39 systems. Both the selection method for period-bounce candidates and the confirmation path that we outlined will aid in future searches for new period-bounce candidates, contributing to the goal of resolving the discrepancy between the predicted high number of period-bouncers and the low number of these systems successfully observed to date.

A Thick Volatile Atmosphere on the Ultra-Hot Super-Earth TOI-561 b

• Authors: Johanna K. Teske, Nicole L. Wallack, Anjali A. A. Piette, Lisa Dang, Tim Lichtenberg, Mykhaylo Plotnykov, Raymond T. Pierrehumbert, Emma Postolec, Samuel Boucher, Alex McGinty, Bo Peng, Diana Valencia, Mark Hammond

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

• Arxiv link: https://arxiv.org/abs/2509.17231

• Pdf link: https://arxiv.org/pdf/2509.17231

• Abstract
  Ultra-short period (USP) exoplanets -- with $R_p \leq 2~$R$_{\oplus}$ and periods $\leq$1 day -- are expected to be stripped of volatile atmospheres by intense host star irradiation, which is corroborated by their nominal bulk densities and previous eclipse observations consistent with bare rock surfaces. However, a few USP planets appear anomalously under-dense relative to an Earth-like composition, suggesting an exotic interior structure (e.g., core-less) or a volatile-rich secondary atmosphere increasing their apparent radius. Here we present the first dayside emission spectrum of the low density (4.3$\pm$0.4 g~cm$^{-3}$) ultra-short period planet TOI-561 b, which orbits an iron-poor, alpha-rich, $\sim$10 Gyr old thick disk star. Our 3-5 $\mu$m JWST/NIRSpec observations demonstrate the dayside of TOI-561 b is inconsistent with a bare-rock surface at high statistical significance, suggesting instead a thick volatile envelope that is cooling the dayside to well below the $\sim$3000 K expected in the bare rock or thin atmosphere case. These results reject the popular hypothesis of complete atmospheric desiccation for highly irradiated exoplanets and support predictions that planetary-scale magma oceans can retain substantial reservoirs of volatiles, opening the geophysical study of ultra-hot super-Earths through the lens of their atmospheres.

First large scale spatial and velocity patterns of local metal-rich stars in the Milky Way

• Authors: Georges Kordopatis, Diane Feuillet, Christian Lehmann, Sofia Feltzing, Ivan Minchev, Vanessa Hill, Heitor Ernandes

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

• Arxiv link: https://arxiv.org/abs/2509.17420

• Pdf link: https://arxiv.org/pdf/2509.17420

• Abstract
  (Abridged) The present-day spatial and kinematic distribution of stars in the Milky Way provides key constraints on its internal dynamics and evolutionary history. We select stars that are more metal-rich than the interstellar medium (ISM) at their guiding radius (the so-called Local Metal-Rich stars, LMR) and investigate their chemo-kinematics. Until recently, existing catalogues did not contain such targets in large quantities, but one can now select many millions of them by using Gaia photometric metallicities. Once selected, we investigate their kinematics and age distributions across the disc, and compare them to the stellar populations having the metallicity of the ISM. Compared to locally born stars with [M/H]=[M/H]_ISM, we find that LMR stars, at a given location, are always older (mean age up to 2 Gyr older) and with velocity dispersions similar or slightly higher. Furthermore, at a given [M/H], LMR stars are older at larger galactocentric radiii, reflecting the fact that they need time to migrate. Finally, whereas we do not find any correlation between the location of the spiral arms and the spatial density of LMR stars, we find that the mean stellar eccentricity and mean ages show smaller values where the spiral arms are. Our results confirm a well established theoretical result that has not yet been formally confirmed via observations on large datasets without modelling: churning is not significantly heating the Galactic disc. Furthermore, the age distribution of these stars rule-out any significant contribution from Galactic fountains as their origin, and confirm the effect of the spiral arms on them.

Islands of Electromagnetic Tranquility in Our Galactic core and Little Red Dots that Shelter Molecules and Prebiotic Chemistry

• Authors: Remo Ruffini, Yu Wang

• Subjects: Subjects:
  Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP)

• Arxiv link: https://arxiv.org/abs/2509.17484

• Pdf link: https://arxiv.org/pdf/2509.17484

• Abstract
  Both the Galactic center and LRDs host million-solar-mass black holes within dense, cold reservoirs of molecular gas, and are electromagnetically tranquil. These conditions enable complex molecular chemistry and may serve as natural laboratories for prebiotic genetic evolution by allowing the synthesis of organic molecules essential for life.

An ancient L- type family associated to (460) Scania in the Middle Main Belt as revealed by Gaia DR3 spectra

• Authors: Roberto Balossi, Paolo Tanga, Marco Delbo, Alberto Cellino, Federica Spoto

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

• Arxiv link: https://arxiv.org/abs/2509.17642

• Pdf link: https://arxiv.org/pdf/2509.17642

• Abstract
  Asteroid families are typically identified using hierarchical clustering methods (HCM) in the proper element phase space. However, these methods struggle with overlapping families, interlopers, and the detection of older structures. Spectroscopic data can help overcome these limitations. The Gaia Data Release 3 (DR3) contains reflectance spectra at visible wavelengths for 60,518 asteroids over the range between 374-1034 nm, representing a large sample that is well suited to studies of asteroid families. Using Gaia spectroscopic data, we investigate a region in the central Main Belt centered around 2.72 AU, known for its connection to L- type asteroids. Conflicting family memberships reported by different HCM implementations underscore the need for an independent dynamical analysis of this region. We determine family memberships by applying a color taxonomy derived from Gaia data and by assessing the spectral similarity between candidate members and the template spectrum of each family. We identify an L- type asteroid family in the central Main Belt, with (460) Scania as its largest member. Analysis of the family's V-shape indicates that it is relatively old, with an estimated age of approximately 1 Gyr, which likely explains its non detection by the HCM. The family's existence is supported by statistical validation, and its distribution in proper element space is well reproduced by numerical simulations. Independent evidence from taxonomy, polarimetry, and spin-axis obliquities consistently supports the existence of this L- type family. This work highlights the value of combining dynamical and physical data to characterize asteroid families and raises questions about the origin of L- type families, potentially linked to primordial objects retaining early protoplanetary disk properties. Further spectroscopic data are needed to clarify these families.

RAVEN: RAnking and Validation of ExoplaNets

• Authors: Andreas Hadjigeorghiou, David J. Armstrong, Kaiming Cui, Marina Lafarga Magro, Luis Agustín Nieto, Rodrigo F. Díaz, Lauren Doyle, Vedad Kunovac

• Subjects: Subjects:
  Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG)

• Arxiv link: https://arxiv.org/abs/2509.17645

• Pdf link: https://arxiv.org/pdf/2509.17645

• Abstract
  We present RAVEN, a newly developed vetting and validation pipeline for TESS exoplanet candidates. The pipeline employs a Bayesian framework to derive the posterior probability of a candidate being a planet against a set of False Positive (FP) scenarios, through the use of a Gradient Boosted Decision Tree and a Gaussian Process classifier, trained on comprehensive synthetic training sets of simulated planets and 8 astrophysical FP scenarios injected into TESS lightcurves. These training sets allow large scale candidate vetting and performance verification against individual FP scenarios. A Non-Simulated FP training set consisting of real TESS candidates caused primarily by stellar variability and systematic noise is also included. The machine learning derived probabilities are combined with scenario specific prior probabilities, including the candidates' positional probabilities, to compute the final posterior probabilities. Candidates with a planetary posterior probability greater than 99% against each FP scenario and whose implied planetary radius is less than 8$R_{\oplus}$ are considered to be statistically validated by the pipeline. In this first version, the pipeline has been developed for candidates with a lightcurve released from the TESS Science Processing Operations Centre, an orbital period between 0.5 and 16 days and a transit depth greater than 300ppm. The pipeline obtained area-under-curve (AUC) scores > 97% on all FP scenarios and > 99% on all but one. Testing on an independent external sample of 1361 pre-classified TOIs, the pipeline achieved an overall accuracy of 91%, demonstrating its effectiveness for automated ranking of TESS candidates. For a probability threshold of 0.9 the pipeline reached a precision of 97% with a recall score of 66% on these TOIs. The RAVEN pipeline is publicly released as a cloud-hosted app, making it easily accessible to the community.

Molecular clouds as a tool to constraint sub-GeV dark matter and primordial black holes

• Authors: A. Salces, P. D. L. T. Luque, M. A. Sánchez Conde

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

• Arxiv link: https://arxiv.org/abs/2509.17692

• Pdf link: https://arxiv.org/pdf/2509.17692

• Abstract
  Despite decades of direct and indirect searches within the Weakly Interacting Massive Particle (WIMP) framework, no conclusive results have been found in the GeV--TeV range. This has motivated exploring alternatives, including new particles and macroscopic objects. Two well-motivated scenarios are sub-GeV DM and Primordial Black Holes (PBHs). Molecular clouds (MCs), typically studied as star-forming sites, can serve as astrophysical laboratories to probe these candidates via their ionization rates. Observations show ionization levels exceeding expectations from known CR fluxes, pointing to an additional ionizing component. Here, we consider electrons and positrons from annihilating and decaying MeV DM particles, as well as Hawking radiation from evaporating PBHs, as possible contributors. We model transport driven by energy losses within the clouds. By comparing predicted ionization rates with observations, conservative constraints are set on the thermally averaged cross section $\langle\sigma v\rangle$, decay lifetime $\tau$ and PBH abundances $f_{PBH}$. The analysis assumes all the observed ionization comes from DM and adopts a 95% confidence level. Results show that, even in the most conservative case of local MCs such as L1551, these constraints are very close to the most competitive bounds from X-ray observations, while inner-Galaxy clouds like DRAGON or G1.4--1.8+87 provide stronger limits, sometimes improving X-ray and cosmological constraints. For sub-GeV DM, MCs exclude parameter space competitive with the one tested by NuSTAR, INTEGRAL, or Voyager, especially below $\sim$30 MeV. In the PBH case, asteroid-mass black holes are restricted to a low fraction of DM, with optimistic scenarios getting close to the strongest limits. This demonstrates the potential of MCs as a novel probe in indirect DM searches.

The young stellar clusters in M51 and the impact of GMC encounters

• Authors: Timmi G. Jørgensen, Ross P. Church

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

• Arxiv link: https://arxiv.org/abs/2509.17846

• Pdf link: https://arxiv.org/pdf/2509.17846

• Abstract
  We investigate the young stellar cluster population of M51 and how it is affected by encounters with giant molecular clouds (GMCs). We combine a galactic model with $N$-body simulations of 5000 unique clusters in the mass range [600 - 24000] $M_{\odot}$. We simulate each cluster twice: with ($C_R$) and without ($C_N$) tidal perturbations from the GMCs. We are able to reproduce the majority of the observed mass- and age functions. However, for the age function we see a large discrepancy for clusters with masses $\sim$ 5000 $M_{\odot}$, which is likely related to incompleteness in the observations. We find that old low-mass clusters, located close to the galactic centre, are most likely to be disrupted. The effect of GMC encounters causes a decrease in survivability by 8 per cent points for the oldest clusters with initial masses below 6000 $M_{\odot}$. For 15 clusters we find that the presence of GMCs can protect the $C_R$ clusters from the rest of the galactic tidal field and thereby cause them to retain a significantly higher fraction of stars compared to the $C N$ clusters. For clusters that are super-virialized we find that the $C_R$ clusters have a higher virial ratio compared to the $C_N$ clusters, which is a result of interactions with GMCs. We see no significant difference between the $C_R$ and $C_N$ populations, indicating that over a time period of 200 Myr the effect of the GMCs cannot be detected.

The Role of the Convective Kissing Instability in Cataclysmic Variable Evolution

• Authors: Conor M. Larsen, James MacDonald

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

• Arxiv link: https://arxiv.org/abs/2509.17906

• Pdf link: https://arxiv.org/pdf/2509.17906

• Abstract
  The convective kissing instability (CKI) is postulated to occur in low mass stars around the fully convective transition. Non-equilibrium $^{3}$He burning leads to the merging of core and envelope convective zones, which causes abrupt decreases in the stellar radius. It has been suggested by van Saders & Pinsonneault (2012) that these effects may be relevant for cataclysmic variables (CVs). We have performed stellar evolution modeling to study the role of the CKI in CV evolution. We find that the CKI has no effect on normal CVs which evolve via magnetic braking and gravitational radiation above the period gap. CKI cycles either do not occur or are abruptly halted once mass transfer begins. If only gravitational radiation is considered, the CKI does occur. The abrupt radius changes can cause detachment phases which produce small period gaps with widths of a few minutes. We describe how the size of the period gaps is controlled by the $^{3}$He profiles of the secondaries. We also discuss how the results of this study apply to the evolution of strong field polars, where the magnetic field of the white dwarf is strong enough to suppress magnetic braking.

Cosmic inventory of the background fields of relativistic particles in the Universe

• Authors: Jonathan Biteau

• Subjects: Subjects:
  Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)

• Arxiv link: https://arxiv.org/abs/2509.17954

• Pdf link: https://arxiv.org/pdf/2509.17954

• Abstract
  The extragalactic background is composed of the emission from all astrophysical sources, both resolved and unresolved, in addition to any diffuse components. In the last decade, there has been significant progress in our understanding of the cosmic history of extragalactic emissions associated with stellar evolution and accretion onto supermassive black holes, largely enabled by the extensive body of multi-wavelength data. The brightness of the extragalactic sky is now measured in photons, neutrinos, and cosmic rays, using observatories on the ground, in the sea, and in the ice, satellites in Earth orbit, and probes at the edge of the solar system. This wealth of disparate data is essential to unraveling the mysteries of the source populations that contribute to the extragalactic background. In this contribution, we present an open database containing the most comprehensive collection of measurements of the extragalactic background spectrum to date. The combination of multi-messenger measurements over 27 frequency decades allows us to estimate the energy density of most extragalactic background components with an uncertainty of less than 30%. We explore the consistency of this cosmic inventory of the observed fields of relativistic particles populating the Universe with the cosmic history of star formation and accretion around supermassive black holes. Models incorporating these cosmic histories, as well as the redshift-dependent luminosity functions of extragalactic sources, currently match the electromagnetic component of the extragalactic background spectrum over 14 frequency decades, from the near UV to sub-TeV gamma rays. The knowledge gained from synthetic population models in the electromagnetic bands may become a crucial tool for understanding the origin of the most energetic extragalactic messengers, neutrinos and ultrahigh-energy cosmic rays.

Impact of nonthermal electron distributions on the triggering of the ion-ion acoustic instability near the Sun: Kinetic simulations

• Authors: M. S. Afify, J. Dreher, S. O'Neill, M. E. Innocenti

• Subjects: Subjects:
  Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph)

• Arxiv link: https://arxiv.org/abs/2509.18032

• Pdf link: https://arxiv.org/pdf/2509.18032

• Abstract
  Context. In a previous paper (Afify et al. 2024), we have investigated the stability threshold of the ion-ion acoustic instability (IIAI) in parameter regimes compatible with recent Parker Solar Probe (PSP, (Fox et al. 2016)) observations, in the presence of a Maxwellian electron distribution. We found that observed parameters are close to the instability threshold, but IIAI requires a higher electron temperature than observed. Aims. As electron distributions in the solar wind present clear non-Maxwellian features, we investigate here if deviations from the Maxwellian distribution could explain the observed IIAI. We address specifically the kappa ( $\kappa$ ) and core-strahl distributions for the electrons. Methods. We perform analytical studies and kinetic simulations using a Vlasov-Poisson code in a parameter regime relevant to PSP observations. The simulated growth rates are validated against kinetic theory. Results. We show that the IIAI threshold changes in the presence of $\kappa$ or core-strahl electron distributions, but not significantly. In the latter case, the expression of an effective temperature for an equivalent Maxwellian electron distribution given in Jones et al. (1975) is confirmed by simulations. Such an effective temperature could simplify stability assessment of future observations.

by olozhika (Xing Yuchen).

2025-09-23