研究動向

astro-ph.EP2026年9月5日

Evidence for LP 890-9d via Transit Timing Variations

Kevin B. Stevenson, Guangwei Fu, Kristin S. Sotzen, E. M. May, Larissa Palethorpe, Jacob Lustig-Yaeger, Ted M. Johnson, Eric Agol et al.

LP 890-9, also known as SPECULOOS-2 and TOI-4306, is a nearby late-M dwarf hosting two confirmed transiting rocky exoplanets. We analyze 20 JWST/NIRSpec PRISM transits of LP 890-9b and LP 890-9c obtained as part of GO program 7073 and detect statistically significant transit timing variations (TTVs), with peak-to-peak amplitudes of ~17 s and ~35 s, respectively. Using analytic linear TTV theory, we find that the known two-planet configuration cannot reproduce the measured TTV amplitudes or super…

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astro-ph.EP2026年9月5日

JWST Excludes Exomoons Down to 0.1 Earth Radii Around a Rocky, Temperate Exoplanet

David Kipping

To date, even with JWST, it has not been possible to test for exomoons as small as the Moon. Only two reported searches for exomoons around bound planets have been attempted with JWST, both of which relied on a single JWST transit. We suggest that the below expectation sensitivity to date is, in part, a product of the considerable intrinsic flexibility of the planet+moon transit model when confronted with a single event, and the presence of unanticipated systematic noise. To test this, we presen…

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astro-ph.GA2026年9月5日

Rapid quenching and early gas depletion in the core of a galaxy protocluster at z=2.2

C. D'Eugenio, H. Dannerbauer, A. Naufal, J. M. Pérez-Martínez, Y. Koyama, P. G. Pérez-González, Y. H. Zhang, T. Kodama et al.

Understanding how galaxy evolution is affected in forming high-z overdensities is a major open question in modern astrophysics. Here, we present the average properties of the quiescent galaxy population recently identified in the core of the Spiderweb protocluster at z = 2.16. By stacking observations from the Hubble Space Telescope (HST; F160W imaging and G141 grism spectroscopy), the James Webb Space Telescope (JWST; PaBeta narrowband imaging), and the Atacama Large Millimeter/submillimeter Ar…

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astro-ph.SRastro-ph.GA2026年9月5日

ROCKETS I: Investigating the Impact of the Rocket Effect on Two Nearby Young Open Clusters Encased in Infrared Bubbles

R. Arun, G. Maheswar, Annapurni Subramaniam, Piyali Saha, T. P. Sudheesh, B. Shridharan, Blesson Mathew, Akhil Krishna R et al.

We introduce ROCKETS (Rocket-driven Cluster Kinematics & Triggered Star-formation), a Gaia based programme investigating kinematic fingerprints of stellar feedback or rocket effect in young star forming regions. We analyse two young clusters with O-type stars enclosed by mid-infrared bubbles, Collinder 69 and IC 1396 as a methodological demonstration on two nearby benchmark regions. Co-moving candidates are selected within an astrometric ellipse defined by the median and median absolute deviatio…

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astro-ph.SR2026年9月5日

Energy Partitioning at the Termination Shock

Judit Szente, Bart van der Holst, Gabor Toth, Merav Opher

We show new results of a global 3D magnetohydrodynamic (MHD) simulation of the Boston University outer heliosphere model where we used a newly developed approach that distributes the non-adiabatic shock heating among the cold protons, electrons, and pickup-ions (PUIs), while maintaining total energy conservation of all ions (cold protons and PUIs) and electrons. In our previous simulations ( E.S. Bair et al. 2025; B. van der Holst et al. 2026), all non-adiabatic shock heating was channeled to th…

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astro-ph.EPastro-ph.GAastro-ph.IMastro-ph.SR2026年9月5日

Enabling Metallicity Measurements of Microlensing Lenses through Multi-band Lens Photometry

Jiyuan Zhang, Gregory Green, Weicheng Zang, Hongjing Yang, Shude Mao

We present the photometric--microlensing metallicity method, which enables metallicity measurements of M-dwarf lenses out to bulge distances by combining their multi-band photometry with the angular Einstein radius. The cool atmospheres of M dwarfs contain abundant molecules, whose broad absorption bands make their positions in an optical--NIR color--absolute magnitude diagram sensitive to metallicity. The angular Einstein radius provides the mass--distance constraint needed to infer the lens ab…

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astro-ph.EP2026年9月5日

A Homogeneous Survey of JWST MIRI Transmission Spectra of 10 Exoplanets

Martin Binet, Nikku Madhusudhan, Måns Holmberg, Subhajit Sarkar

The launch of JWST has enabled unprecedented atmospheric characterization of exoplanets. In particular, the JWST-MIRI instrument in the mid-infrared enables probing of molecular species that are harder to detect in the near-infrared. This has come to the fore with the first MIRI-LRS observation of a candidate hycean world, K2-18 b, with potential signs of dimethyl sulfide in its atmosphere. The statistical significance of this result has been debated in subsequent works, arguing instead for the…

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astro-ph.IM2026年9月5日

What is new in NuRadioMC: Multilayer Analytic Raytracer

Hannes Warnhofer, Sjoerd Bouma, Vital De Henau, Bryan Hendricks, Jakob Henrichs, Nils Heyer, Enrique Huesca Santiago, Annanay Jaitly et al.

NuRadioMC is a framework for the simulation of ultra-high-energy neutrino detectors that measure the radio signal emitted in neutrino-induced particle cascades used in different radio neutrino experiments. We present an extension to the analytic raytracing method for multilayered exponential refractive index models, where the full refractive index profile is described by a set of different single-exponential layers, supporting realistic medium descriptions at various experiment sites while maint…

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astro-ph.EP2026年9月4日

Planetary gas gaps and kinematic signatures in the planet forming disk around WISPIT 2

Nienke van der Marel, Jochen Stadler, Andres F. Izquierdo, Ruobing Dong, Bertram Bitsch, Jake Byrne, Richelle van Capelleveen, Chloe Lawlor et al.

The giant planet formation process in disks of gas and dust surrounding young stars is observationally still poorly constrained. Direct detection of protoplanets within the disk remains limited with current facilities. Indirect observational evidence of protoplanets through substructures or deviations from Keplerian rotation in the gas remains ambiguous in absence of detected planets. The lack of the combined detection of substructures and their corresponding planets makes it challenging to conn…

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astro-ph.GA2026年9月4日

Stellar Population and Dynamical Modeling of Galaxies with Kinematically Misaligned Components: Age and Metallicity of Structural Components

V. S. Goradzhanov, K. O. Parfenov, D. D. Mishurin, O. K. Sil'chenko

We present stellar population and orbit modeling of two galaxies with kinematically misaligned components, PGC 35706 and LEDA 2220522, extending previous Schwarzschild dynamical models. Using spatially resolved age and metallicity maps from NBursts full spectral fitting of MaNGA data with the E-MILES grid, we solve a regularized bounded linear inverse problem that assigns light-weighted SSP-equivalent age, metallicity, and mass-to-light ratio to orbital cells in the $(R,λ_z)$ plane. Component me…

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astro-ph.HE2026年9月4日

Exploring the connection between Fast Radio Bursts and binary neutron star mergers

Barbara Patricelli, Maria Grazia Bernardini, Cecilia Sgalletta, Michela Mapelli

Fast Radio Bursts (FRBs) are highly energetic radio sources whose duration is of the order of milliseconds. The physical origin of these sources is still unknown. Many models suggest magnetars as possible progenitors of FRBs, and this is supported by the association between FRBs and the Galactic magnetar SGR 1935+2154; other proposed progenitors include binary neutron star (BNS) mergers, that are themselves linked to magnetar formation. In this work we investigate the possible connection between…

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astro-ph.IMastro-ph.EP2026年9月4日

Active focal plane phase mask coronagraphy with a discrete pixelated device: I. Study of the theoretical performance trade space

Liurong Lin, Axel Potier, Ruben Tandon, Lucas Marquis, Jonas G. Kühn

Recent advances in high-contrast exoplanet imaging instrumentation have introduced the concept of adaptive coronagraphy. For example, liquid-crystal-on-silicon spatial light modulators can be used as programmable phase masks or digital micro-mirror devices as configurable pupil apodizers. Adaptive coronagraphy offers the ability to adjust in real time to changing observing conditions and science goals, such as switching between blind surveys and follow-ups of known objects, or optimizing observa…

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astro-ph.IM2026年9月4日

Laboratory characterization of Hierarchical Fringe Tracking

Roxanne Ligi, Stéphane Lagarde, Romain Petrov, Sylvie Robbe-Dubois, Julien Dejonghe, Fatmé Allouche, Teng Xu, Wei Wei et al.

One of the main limitations in long-baseline interferometry lies in its fringe tracking sensitivity. The challenge is therefore to maximize this sensitivity while minimizing the spreading of the signal on the detector. This is the goal at the core of the hierarchical fringe tracking (HFT) concept. We present the laboratory characterization of the $2^{nd}$ generation HFT chips operating in the near infrared (H band) for up to 4 telescopes with more linear phase and group delay estimators, allowin…

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astro-ph.GA2026年9月4日

The dispersal law of young star clusters: free expansion -- A Gaia/eROSITA census of Orion and Sco--Cen

João Alves, Stefan Meingast, Alena Rottensteiner

We measure how young star clusters disperse over time in the two nearest star-forming complexes. Our sample comprises 44 \texttt{SigMA}-\textit{Gaia}-defined clusters in Orion and 31 in Sco--Cen, with isochronal ages of 2--25\,Myr. We extend each cluster's census with \textit{eROSITA}-selected young stars that share its parallax and motion and lie within the distance they could have traveled ballistically since birth. By 10--30\,Myr, about one in three former cluster stars lies outside the clust…

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astro-ph.GA2026年9月4日

PPN--spin degeneracies in mock S62-like stellar-orbit inference

Shant Khlghatyan

We investigate the degeneracies between black hole (BH) spin effects and parametrized post-Newtonian (PPN) parameters in the relativistic orbital dynamics of S2-like and S62-like stars orbiting Sagittarius A$^{\ast}$. Using a 1PN+SO Hamiltonian framework and synthetic astrometric and radial velocity datasets, we perform Bayesian parameter inference. For current baseline observational precisions, the dominant relativistic observable--the Schwarzschild periapsis advance--allows the recovery of the…

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astro-ph.COastro-ph.GA2026年9月4日

Euclid. A two-point correlation approach to diagnosing star-related systematics in the Euclid spectroscopic survey

Euclid Collaboration, I. Risso, B. R. Granett, E. Branchini, A. Veropalumbo, B. Kubik, P. Monaco, J. Comparat et al.

The Euclid spectroscopic survey will measure galaxy clustering with unprecedented precision, requiring stringent control of observational and instrumental systematics. Star-related effects may contaminate spectroscopic images through photometric persistence and imperfect masking of stars. We characterized their impact on galaxy clustering analyses, focusing on angular features identifiable in the data. We used angular and spatial auto- and cross-correlation statistics. For galaxies, we used mock…

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astro-ph.EP2026年9月4日

Stability of circumbinary planets: the role of binary properties and migration scenarios

Romain Grane, Nicolás Cuello, Mario Sucerquia, Emmanuel Gianuzzi, Milenne Ávila-Bravo, Carolina Charalambous, Amaury H. M. J. Triaud

Among the thousands of exoplanets detected to date, only a very small fraction are classified as circumbinary planets, and this number becomes negligible when considering low-mass planets. This rarity may partly result from observational biases, but also from the challenging dynamical environment of binary systems, which can prevent the long-term stability of planetary orbits. It is therefore essential to investigate the conditions that enable the formation and survival of stable circumbinary pl…

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astro-ph.SRastro-ph.GAastro-ph.HE2026年9月4日

Can isolated binaries form unequal-mass binary black-hole mergers with a high-spin primary black hole?

Xiao-Tian Xu, Dong Lai, Bin Liu

GWTC-5 has revealed a subpopulation of merging binary black holes (BBHs) with a high-spin primary black hole (BH) and possibly unequal BH masses. GW241110 additionally exhibits a large spin-orbit misalignment, which suggests a hierarchical-merger origin. However, other formation scenarios are possible or even likely, especially for events without constraints on spin-orbit misalignment. As an alternative to hierarchical mergers, we investigate whether binary evolution can produce unequal-mass BBH…

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gr-qcastro-ph.HEnucl-th2026年9月4日

Probing Neutron Star Equation of State Universality with Gravitational Waves

Praveer Tiwari, Ajit Kumar Mehta, K. G. Arun

Current neutron star equation-of-state inferences assume that a common equation of state describes all neutron stars. However, {poorly understood dense-matter physics may give rise to distinct long-lived stellar subpopulations following different mass--tidal-deformability relations, invalidating this assumption. In this Letter, we demonstrate that next-generation gravitational-wave observatories enable neutron star equation-of-state universality to be transformed from an assumption into a testab…

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astro-ph.EPastro-ph.IM2026年9月4日

Modelling Palomar Transients: Constraints from Reflection Geometry and Orbital Altitude

Beatriz Villarroel, Alina Streblyanska, Hichem Guergouri, Brian Doherty, Matthew Shultz, Stephen Bruehl

Recent searches of digitised photographic plates from the Palomar Observatory have uncovered tens of thousands of short-lived transients, each visible in only a single exposure. Their morphologies indicate sub-second flashes, consistent with specular reflections from highly reflective objects in near-Earth orbits. In this paper, we present a modelling study using geometric shadow modelling, Monte Carlo simulations, and photometric constraints to infer their physical properties. We examine the ob…

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astro-ph.EP2026年9月4日

Gravitational instability in planet-forming discs

Cristiano Longarini, Giuseppe Lodato

During the earliest phases of star and planet formation, a young star is surrounded by a disc that can become gravitationally unstable. Indeed, if the protoplanetary disc is sufficiently massive, its self-gravity triggers the formation of large scale spiral arms, transporting angular momentum, trapping solid particles and, potentially, collapsing to form sub-stellar companions. In this paper, we review the theoretical and observational advances in the study of gravitational instability in protop…

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astro-ph.HE2026年9月4日

Nonstationary Stochastic Timing Signatures in the Prompt Gamma-Ray Light Curve of GRB 170817A

Lin Xie, Dahai Yan

We investigate time-dependent stochastic structure in the weak prompt gamma-ray emission of GRB 170817A using change-point and deep-kernel Gaussian-process (GP) models. The analysis is based on the 10-300 keV Fermi/GBM light curve with 0.10 s time resolution. Two change-point configurations identify similar covariance transitions at 0.269 and 0.237 s after the gravitational-wave merger, with 10-90% transition widths of 0.441 and 0.393 s, respectively. At the representative gate-defined boundary…

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astro-ph.GA2026年9月4日

Corona Australis 151: an extremely young protostar

E. Redaelli, S. Spezzano, P. Caselli, J. Harju, D. Arzoumanian, O. Sipilä, A. Belloche, F. Wyrowski et al.

Context. Prestellar cores are the birthplace of stars and planetary systems, but they are short-lived objects, since the initial stages of dense core evolution, collapse, and the formation of a protostellar seed are fast. In an effort to build a catalogue of bona-fide prestellar cores in the Solar neighbourhood, we used APEX observations to identify dynamically evolved cores among dense cores observed with Herschel. One of them, Corona Australis 151, stood out because of its centrally peaked str…

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astro-ph.HE2026年9月4日

The October 2022 flare in OJ 287 and the mass of its primary black hole

Mauri J. Valtonen, Staszek Zola, Manpreet Singh, Andrei V. Berdyugin, Kari Nilsson, A. Gopakumar, Alok C. Gupta, Tapio Pursimo et al.

The bright blazar OJ~287 has demonstrated a sequence of flares, which are well explained by a quasi-Keplerian orbit model. The flares are associated with the impact of the secondary on the accretion disk of the primary. The orbit must precess in order to produce the correct sequence of flares, and from the precession rate we calculate the mass of the primary. This precession rate gives the mass of the primary $M_{BH} = (18.35\pm0.05) \times 10^9 M_{\odot}$. Two kinds of flares have been identifi…

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astro-ph.EPastro-ph.IM2026年9月4日

Updated in-flight calibration of the Hayabusa2/NIRS3 spectrometer: new global near-infrared photometric properties of asteroid (162173) Ryugu

Antonin Wargnier, Eri Tatsumi, Koki Yumoto, Mayumi Ichikawa, Shin-ya Murakami, Yuichiro Nagai, Kazuhiro Honda, Yasuhiro Yokota et al.

The Near InfraRed Spectrometer (NIRS3) onboard Hayabusa2 observed asteroid (162173) Ryugu, searching especially for signatures of water-bearing minerals. However, during the mission, absolute reflectance measured by the Telescopic Optical Navigation Camera (ONC-T) and NIRS3 showed a systematic offset. Additionally, touchdown operations have modified the instrumental response, which has made post-second-touchdown data less reliable. Correction of these issues is crucial to interpret the subtle sp…

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astro-ph.GA2026年9月4日

Rubin J122659.4+090236: An Extremely Low Surface Brightness Galaxy Candidate Discovered in the Rubin LSST Early Data Preview 2

Dipanjan Mitra, Kanak Saha, Sugata Kaviraj, Alister W. Graham, Sandro Tacchella, Ricardo Demarco, Dieu D. Nguyen, Elham Saremi et al.

We report the serendipitous discovery of an exceptionally low surface brightness galaxy (LSBG) candidate, Rubin J122659.4+090236, in Rubin Observatory imaging of the interacting NGC 4410 system, identified in the Cosmic Treasure Chest public release. 2D Sérsic modelling of the Rubin g, r, and i images reveals a nearly round system with a shallow profile (n ~ 0.4), an effective radius of R_e ~ 6'', and central surface brightnesses of $μ_{0,g}=27.52\pm0.04$, $μ_{0,r}=27.62\pm0.07$, and $μ_{0,i}=27…

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astro-ph.EP2026年9月4日

Mapping the WISPIT2 Planet-Hosting Cavity at Sub-Hill-Radius scales

Myriam Benisty, Stefano Facchini, Richard Teague, Francesco Zagaria, Pietro Curone, Viviana Pezzotta, Jaehan Bae, Gabriele Cugno et al.

We present new deep, very high angular resolution observations of the sub-mm continuum (19x13 mas) and 12CO (67x52 mas) emission from the disk surrounding the planet host WISPIT2. Our analysis reveals a clear gas gap carved by WISPIT 2b and an empty cavity within the orbit of WISPIT 2c. We also find a gaseous and optically thin dusty ring located between the orbits of the two planets. Channel maps show a pronounced change in the emission surface height of the disk, which transitions from flat wi…

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astro-ph.EP2026年9月4日

The metallicity of giant exoplanets around low-mass stars and how Ariel can help

Ravit Helled, Sho Shibata, Shubham Kanodia, Billy Edwards

Giant planets orbiting low-mass stars represent a unique population of giant planets that can be studied to constrain planet formation theory. Surveys of transiting giant exoplanets around M-dwarfs (GEMS) allow for measurement of their masses and radii, which in turn can be used to estimate their bulk densities. Coupling these observations to interior structure and evolution models can yield the bulk metallicity of these planets, however there are degeneracies to this that are improved by measur…

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astro-ph.EPastro-ph.GA2026年9月4日

Multi-Wavelength Post-Perihelion Polarimetry of Interstellar Comet 3I/ATLAS

Zuri Gray, Galin Borisov, Ludmilla Kolokolova, Johannes Markkanen, Yuna G. Kwon, Stefano Bagnulo, Alberto Cellino, Rosemary C. Dorsey et al.

We present new post-perihelion polarimetric observations of the third discovered interstellar object, 3I/ATLAS (C/2025 N1; hereafter 3I), obtained using FORS2 at the Very Large Telescope, ALFOSC at the Nordic Optical Telescope, and FoReRo2 at the 2 m Ritchey-Chrétien-Coudé telescope. The observations span phase angles 1-30$^{\circ}$, providing the most extensive polarimetric phase angle coverage obtained for an interstellar object to date. The post-perihelion measurements reveal that the unusual…

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astro-ph.EP2026年9月4日

Disk dispersal freezes overstable resonant librations

Linghong Lin, Beibei Liu

Context. Convergent migration in a gaseous protoplanetary disk can capture a planet pair into mean-motion resonance. Eccentricity damping can subsequently make the resonant libration overstable and drive the pair out of resonance. Most studies of this process, however, assume a static disk. Aims. We examine how the decay of disk torques during dispersal changes this outcome and whether it can freeze an overstable libration before the pair escapes. Methods. We describe disk dispersal by allowing…

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