研究動向

astro-ph.EP2026年7月22日

A comprehensive study of comet 67P/Churyumov-Gerasimenko in the 2021/2022 apparition. II. Colorimetry, polarimetry, modeling

Vera Rosenbush, Oleksandra Ivanova, Johannes Markkanen, Igor Lukyanyk, Valerii Kleshchonok, Ludmilla Kolokolova, Colin Snodgrass, Elena Shablovinskaya et al.

This paper presents the second part of our multi-technique observational study of comet 67P during its 2021-2022 apparition. While the first paper focused on photometry and spectroscopy, here we investigate the dust color and linear polarization of the coma. Imaging in the g-sdss and r-sdss filters was obtained with the 6-m BTA SAO Telescope, and aperture polarimetry was performed with the 2.6-m Shajn Telescope (CrAO) and the 2-m RCC Telescope. Observations at phase angles of 47.9 deg (6 October…

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astro-ph.GAastro-ph.SR2026年7月22日

Anharmonic Infrared Emission of Cyano-Substituted Polycyclic Aromatic Hydrocarbon Molecules: Cyanonaphthalenes as a Case Study

Tao Chen, Kaijun Li, Aigen Li

Recent detections of cyano-substituted polycyclic aromatic hydrocarbons (cyano-PAHs) highlight them as key tracers of nitrogen heterocycles in the interstellar medium (ISM). However, their infrared (IR) identification requires anharmonic vibrational radiative models that account for dynamic cooling across diverse environments. We provide IR cascade emission spectra for neutral, cationic, and anionic 1- and 2-cyanonaphthalene (1- and 2-CNN) under representative astrophysical conditions, investiga…

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astro-ph.GA2026年7月22日

LMC-induced Perturbations in the Milky Way Halo II: Bridging Field-level Inference and Summary-level Simulation-Based Inference

Yanjun Sheng, Yuan-Sen Ting, Tomasz Różański, Xiang-Xiang Xue, Roland M. Crocker, Jiashu Pan

The gravitational interaction between the Milky Way (MW) and the Large Magellanic Cloud (LMC) drives the outer halo into dynamical disequilibrium, imprinting the masses and structural parameters of both galaxies onto the 6D phase-space distribution of halo tracers. This signal has been characterised with summary statistics ranging from low-order velocity moments to basis function expansions, yet how much information these summaries discard, and whether they are complementary, remains unclear. We…

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astro-ph.GAastro-ph.SR2026年7月22日

The UK Infrared Telescope M33 monitoring project. VI. Feedback from dusty stellar winds across the galactic disc

Atefeh Javadi, Jacco Th. van Loon, Mina Alizadeh, Seyed Azim Hashemi, Elham Saremi

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33 (Triangulum). In this sixth paper of the series, we measure the dust and gas mass-loss rates by the pulsating Asymptotic Giant Branch (AGB) stars and red supergiants (RSGs) across the stellar disc of M33. We combined our time-averaged near-IR photometry with the multi-epoch mid-IR photometry obtained with the Spitzer Space Telescope, and employed a combination of spect…

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astro-ph.IMgr-qcphysics.ins-det2026年7月22日

Noise reduction in suspension control with photon-pressure actuator for CHRONOS gravitational wave detector

Daiki Tanabe, Yuki Inoue, Mario Juvenal S. Onglao

Improving sub-Hz sensitivity of gravitational wave (GW) detectors is important to detect heavier binary black hole mergers and study phenomena in stronger gravity fields. Torsion-bar-based GW detectors have been projected to focus on low-frequency GW. Among noise sources of GW detector, actuation noise induced by vibration of force sources and fluctuation of environmental magnetic fields is one that increases in low frequency. In this study, we propose photon-pressure actuator as a solution to i…

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astro-ph.SR2026年7月22日

Oscillatory reconnection and resonant response to wave excitation in 2D coronal null points

Konstantinos Karampelas, Tom Van Doorsselaere

Null points are magnetic field singularities, where the magnetic field strength rapidly drops to zero. In the solar atmosphere, null points are known sites of magnetic reconnection and wave generation and are associated with highly energetic phenomena, such as flares. The aim of this study is to explore the connection between the properties of oscillatory reconnection at null points and the latter's nature as resonant cavities for waves. We perform a set of 2D and 2.5D magnetohydrodynamics simul…

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astro-ph.HE2026年7月22日

Constraints on the VHE counterpart of two binary black hole mergers observed by the MAGIC and CTAO LST-1 telescopes

K. Abe, S. Abe, J. Abhir, A. Abhishek, V. A. Acciari, F. Acero, A. Aguasca-Cabot, I. Agudo et al.

We present very-high-energy gamma-ray observations of two binary black hole merger candidates, GW240615_113620 and GW241125_010116, performed with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes and the first Large-Sized Telescope of the Cherenkov Telescope Array Observatory's (CTAO LST-1). GW240615_113620 was the best localized event of the fourth observing run of the LIGO-Virgo-KAGRA gravitational waves interferometers. GW241125_010116 was temporally and spatially coincident w…

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astro-ph.GA2026年7月22日

Nebular continuum in high-redshift galaxies with JWST

Henrique Miranda, Ciro Pappalardo, José Afonso, Polychronis Papaderos, Rodrigo Carvajal

Studying the relevance of accounting for both stellar and nebular continuum emission when performing optical spectral fitting has been mainly limited to galaxies in the local Universe. The high-quality spectroscopy provided by JWST is now opening the possibility of carrying out these studies in the younger Universe. We aim to estimate the nebular continuum contribution (X$_{\text{neb}}$) of high-redshift star-forming (SF) galaxies, explore its relation to common tracers and galaxy properties, an…

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astro-ph.COastro-ph.GA2026年7月22日

Ringing of the Reionization: A first direct measurement of the intergalactic pressure smoothing scale at redshift z>4.2 as imprinted onto small-scale peculiar velocities in the Lyman-alpha forest

Vid Iršič, Matteo Viel, Martin G. Haehnelt, James S. Bolton, Ewald Puchwein, Luke I. Gilmartin

The epoch of reionization leaves detectable imprints in the thermal history of the Universe. In particular, the fast ionization fronts passing over cold gas in the cosmic web overpressurize the gas, leading to the well-established phenomenon of pressure smoothing due to the hydrodynamic response of the gas. Although the effect has been indirectly measured from the power spectra of the Lyman-$α$ forest over the past decades, very few examples exist of directly measuring the typical scale associat…

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astro-ph.IM2026年7月22日

CATKit2-HCI: a collaborative framework for advancing high-contrast coronagraph testbeds

Rémi Soummer, Iva Laginja, Emiel H. Por, Raphaël Pourcelot, Sarah Steiger, Bryony Nickson, Alexis Lau, Pierre Baudoz et al.

High-contrast exoplanet imaging requires dedicated laboratory testbeds for the development and validation of coronagraph architectures, wavefront sensing and control methods, calibration strategies, and system-level observing concepts. These testbeds often share similar software needs, yet many tools are developed independently at each institution. The CATKit2-High-Contrast-Imaging collaboration, or CATKit2-HCI, addresses this gap by providing a shared software framework for reusable HCI infrast…

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astro-ph.SR2026年7月22日

Reversive and Non-Reversive Magnetic CP Stars. I. Catalog

I. I. Romanyuk

An analysis of the distribution of signs of the longitudinal magnetic field component $B_z$ is presented for a sample of 307 chemically peculiar (CP) stars with reliably measured magnetic fields. For each star, the root-mean-square field $B_{\rm rms}$ and the extreme values of $B_z$ are used to classify the field configuration as either reversive or non-reversive. Among the 173 non-reversive stars, 100 exhibit a predominantly negative $B_z$ sign, while only 73 display a positive sign, correspond…

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astro-ph.HE2026年7月22日

Peculiar Behavior of Optical Polarization in Blazar 1ES 1959+650: Role of Jet Magnetic Field and Geometry

A. Singh, A. Tolamatti, K. K. Singh, A. C. Gupta, K. K. Yadav

Measurements of high degree of optical polarization from blazars provide a strong evidence for the optically thin synchrotron radiation from the relativistic leptons in the jet. This in turn characterizes the presence of a partially ordered magnetic field in the emission region. However, the topology of magnetic field and acceleration of electrons to ultrarelativistic energies within the blazar jet are poorly understood. In this work, we investigate the decade long optical light curve of the wel…

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gr-qcastro-ph.IM2026年7月22日

Characterization of the Scattered Light Noise in KAGRA Interferometer

Shih-Hong Hsu, Hirotaka Yuzurihara, Chia-Jui Chou, Yi Yang

In a gravitational wave (GW) telescope, non-stationary noise can prevent stable interferometer operation and limit the GW analyses. Among the non-stationary noise, we focus on the scattered light noise. It fluctuates across a wide frequency band within a short time. Therefore, the scattered light noise can mimic the GW signal, increase the false alarm rate, or bias the parameter estimation results. In this work, we propose a new analysis method, named f-cluster, to characterize these features wi…

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astro-ph.SR2026年7月22日

Origin of the Long-Period Radial Velocity Variation in the Red Supergiant HD 216946 (V424 Lac)

Byeong-Cheol Lee, Myeong-Gu Park

We present precise radial-velocity (RV) observations of the K-type red supergiant HD~216946 (V424 Lac) obtained over approximately 22 years with the Bohyunsan Optical Astronomy Observatory Echelle Spectrograph (BOES). The RV measurements reveal a significant long-period variability with a period of 1365 days. To investigate its origin, we analyzed the RV data together with line-profile variations (LPVs), chromospheric activity indicators, and published photometric variability. The LPVs exhibit p…

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astro-ph.GAastro-ph.CO2026年7月22日

From Dark Matter to Galaxies: Halo-Free Mock Generation via Conditional Point-Cloud Diffusion

Kana Moriwaki, Ken Osato, Naoki Yoshida

We present a diffusion-based generative model for constructing realistic galaxy catalogues from dark matter density fields. The model takes a three-dimensional dark matter density field as input and generates galaxies directly as a point cloud with positions and physical properties, including star formation rate (SFR), without identifying dark matter haloes or subhaloes. We train the model on galaxy catalogues from the IllustrisTNG hydrodynamical simulation. The generated catalogues reproduce th…

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astro-ph.SR2026年7月22日

Metric Type II Radio Emission associated with Coronal Mass Ejections of Large Angular Widths: Some New Insights

Mayank Rajput, Susanta Kumar Bisoi, Janardhan Padmanabhan

Solar Type II radio bursts are manifestations of shocks produced by explosive and eruptive solar activities, such as solar flares and coronal mass ejections (CMEs). Metric range or coronal Type II bursts are interesting because of their association with CME-driven shocks. It is therefore important to examine the correlation between the properties of Type II bursts and the associated CMEs. This, in turn, would be useful in understanding the impact of CMEs on space weather and geomagnetic activity…

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astro-ph.SR2026年7月22日

Boundary conditions for radial pulsations in AGB envelopes

Jan Zalewski

We present a formulation of outer and inner boundary conditions for radial non-adiabatic pulsations in AGB/post-AGB envelopes in terms of local structure of pulsation equations. This approach provides a framework to construct classes of boundary condition selectors. We show that the pulsation spectrum is primarily determined by the choice of the outer boundary selector. Different choices of the two-dimensional subspace at the outer boundary lead to different types of pulsation spectra ranging fr…

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astro-ph.SRastro-ph.EP2026年7月22日

A Search for Exoplanets around Northern Circumpolar Stars X. The origin of radial velocity variations in the evolved star HD 216595

Sang-Hee Kim, Byeong-Cheol Lee, Shenghong Gu, Jae-Rim Koo, Beomdu Lim, Myeong-Gu Park, Huan-Yu Teng, Yeon-Ho Choi et al.

Detecting planetary companions around evolved stars, particularly asymptotic giant branch (AGB) stars, is challenging due to intrinsic stellar variability such as surface convection, pulsations, and mass loss, which can produce radial velocity (RV) signals that mimic Keplerian motion. We investigate the origin of long-period, low-amplitude RV variations observed in the AGB star HD 216595 based on high-resolution spectroscopic data spanning approximately 16 years obtained with the Bohyunsan Optic…

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astro-ph.SRastro-ph.EP2026年7月22日

2D hydrodynamical simulations of Be star decretion disc formation through boundary layer effects

Madeline Overton, Zhaohuan Zhu, Rebecca G. Martin, Jiayin Dong

Be stars are massive main-sequence stars rotating close to their breakup rate. They possess a decretion disc of material built up due to mass loss from the star, however, there is not a consensus to the mechanism responsible for the formation of the disc because of their sub-breakup spin rates. We present the first 2D hydrodynamical simulations of the formation of a Be star decretion disc from a rapidly rotating star due to boundary layer effects that reduce the rotation rate of the disc close t…

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astro-ph.EP2026年7月22日

CAFE follow-up of TESS hot Jupiter candidates left behind: I. Five newly confirmed planets and a false positive

J. Lillo-Box, C. Cifuentes, O. Balsalobre-Ruza, B. Montesinos, D. Latham, K. A. Collins, D. Ciardi, G. Hébrard et al.

Hot Jupiters are key targets for understanding planet formation, migration, and atmospheres. Yet, most ground-based follow-up resources for the TESS mission are focused on confirming low-mass planet candidates, leaving many giant planets without mass determinations or definitive confirmation. We use the \cafe{} spectrograph at Calar Alto Observatory to monitor the radial velocity of stars hosting hot-Jupiter candidates that have received little follow-up, aiming to confirm their planetary nature…

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astro-ph.SR2026年7月22日

One cluster, two clusters, no cluster? -- The curious case of HSC 2686 and Lynga 3

Andreas Ritter, Quentin A. Parker, Xizhe Xie, Xingyi Guo

This study was motivated by the search for Planetary Nebulae (PNe) and Open Cluster (OCs) associations. Only 5 PNe are currently in Galactic OCs among the previous $\sim4,800$ OCs known. They are valuable because as cluster members their properties can be linked to their progenitor stars, something not possible for general field PNe. Since the GAIA astrometric satellite first data release, thousands of new OC candidates have been identified. This offers fresh motivation to search them as hosts f…

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astro-ph.SR2026年7月22日

Solar differential rotation driven by baroclinic forcing

L. S. Menicucci, G. Guerrero, M. Dikpati, R. Hester, J. Zhang, P. K. Smolarkiewicz

A combination of recent observations and numerical simulations has called into question whether Sun's interior is characterized by strong turbulent convection, a problem known as convective conundrum. In light of a possible absence of vigorous convective motions, we examine whether the Sun's differential rotation, previously assumed to be tightly coupled to Reynolds stresses, may instead be sustained by the presence of a background latitudinal entropy gradient in thermal wind balance. By perform…

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astro-ph.SR2026年7月22日

Exploring the Small-scale Magnetic Fields in the Atmosphere of HD 49385 by Asteroseismic Analysis

Yuetong Wang, Yaguang Li, Yan Li, Guifang Lin, Tao Wu

Recent asteroseismic studies have shown convincing evidences that magnetic fields may exist in the interior of some pulsating red giants. Inspired by this breakthrough, we explored the effect of small-scale magnetic fields on the p-mode oscillations in an evolved star, HD 49385. {\bf We incorporate a modified Eddington $T$-$τ$ equation that phenomenologically mimics the effect of the magnetic fields in the atmosphere of HD 49385,} and calculate the frequencies of p-modes with $l=0$, 1, and 2. By…

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astro-ph.SR2026年7月22日

Asteroseismic Analysis of a Red Giant KIC 9145955 by Including the Small-scale Magnetic Fields in the Atmosphere

Yuetong Wang, Guifang Lin, Yan Li, Tao Wu, Yaguang Li

Recent convincing evidence is found within asteroseismology that suggests the magnetic fields exist in three red giants. Research on small-scale magnetic fields in the Sun and HD 49385 has shown that they have a certain corrective effect on the systematic discrepancies between observed and theoretical frequencies. Here we apply a similar method applied for the Sun to a red giant, KIC 9145955, to explore the impact of small-scale magnetic fields in the photosphere on its frequencies. We find that…

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astro-ph.GA2026年7月22日

When Galaxies Refuel: Evolution of the Perturbed Spiral Galaxy NGC1385

Xiaoyu Kang, Eva Sextl, Rolf-Peter Kudritzki, Hassen M. Yesuf, Fenghui Zhang, Ruixiang Chang, Xiejin Li, Yunkun Han et al.

The spiral galaxy NGC 1385 is characterized by a vigorous and protracted history of star formation, particularly in its central regions, leading to a current star formation rate that surpasses those of comparable systems. We analyze the evolution history of the galaxy using spatially resolved optical and submillimeter spectroscopy obtained from the PHANGS survey combined with WALLABY radio survey data. We construct radial distributions of star formation rate and the interstellar medium (ISM) neu…

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astro-ph.HEastro-ph.SR2026年7月22日

No Surviving Companion to the Galactic SN 1181: Evidence for a Double-Degenerate Channel for Type Iax Supernovae

Kohki Uno, Daichi Tsuna, Daichi Hiramatsu, Tomoya Kinugawa, Takatoshi Ko

Type Iax supernovae (SNe Iax) are the recently-established, yet peculiar subclass of thermonuclear supernovae, whose progenitor systems and explosion mechanisms remain debated. A leading scenario is a single-degenerate channel, in which a white dwarf accreting from a He-star companion undergoes a pure deflagration, leaving both a bound remnant and surviving companion. The Galactic SN 1181, whose distinctive properties are consistent with an SN Iax involving a weak explosion and bound white dwarf…

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astro-ph.SRastro-ph.EP2026年7月22日

The magnetic field strength of a methane dwarf measured from its radio spectral cutoff

Timothy W. H. Yiu, Harish K. Vedantham, Joseph R. Callingham, Timothy W. Shimwell

Brown dwarfs and gas-giant planets are expected to emit coherent radio emission via the electron cyclotron maser instability (ECMI) mechanism powered by non-thermal electrons in their magnetospheres. Detection of a characteristic spectral cutoff in their cyclotron emission is likely to be the only feasible route to measure their magnetic field strengths. Previous radio measurements of a subset of cold brown dwarfs (spectral type T or methane dwarfs) have not shown such a cutoff at frequencies as…

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astro-ph.GAastro-ph.IM2026年7月22日

AGNFormer I: Reconstruction of AGN spectra using a probabilistic transformer model

Benedict L. Rouse, Franz E. Bauer, Tomasz Różański, Guillermo Cabrera-Vives, Patricia Arévalo, Cristóbal Rodrigo Donoso Oliva, Pavlos Protopapas, Gordon T. Richards et al.

We explore how an uncertainty-aware transformer-based architecture can leverage information embedded across the entire observed optical spectra of AGN, focusing on the algorithm's ability to predict unseen or masked parts of luminous AGN spectra. This provides a direct probe of the learnable correlations between AGN continua and broad lines. We introduce AGNFormer, a transformer model trained to predict the mean expected flux and variance in masked spectral regions (major broad lines to ${\pm}10…

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astro-ph.EP2026年7月21日

Dynamically Selected Mass-Radius Relationship for Low Mass Exoplanets

Brad Hansen, Austin Mao

We study the mass-radius relationship of planets in multiplanet systems as a function of their dynamical architecture. We isolate those planets whose proximity to resonance indicates that they have not undergone significant dynamical instability since formation, and therefore have not experienced a late giant impact with another planet. We compare the properties of these planets to those whose orbital architectures suggest a high probability of having experienced a giant impact. We find that pla…

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astro-ph.IM2026年7月21日

RNDR noise modeling in first-generation Single electron Sensitive Readout (SiSeRO) devices

Tonya L. Peshel, Abigail Y. Pan, Tanmoy Chattopadhyay, Steven W. Allen, Marshall W. Bautz, Michael Cooper, Kevan Donlon, Catherine E. Grant et al.

Flagship observatories require single-photon detectors with ultra-fast readout, sub-electron noise performance, and scalable large-format architectures. The X-ray Astronomy and Observational Cosmology group at Stanford, in collaboration with the MIT Kavli Institute and MIT Lincoln Laboratory, is developing readout technologies for next-generation detectors. Prototypes employing Single-electron Sensitive Readout (SiSeRO) amplifiers demonstrate excellent read noise and spectral performance using r…

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