研究動向

astro-ph.GA2026年9月17日

Rubin LSST DP2 unveils almost-dark galaxies in the Virgo Cluster

Minh Ngoc Le, Johan H. Knapen, Željko Ivezić, Junais, Aaron Watkins, Dan S. Tanaru, Pierre-Alain Duc, Anthony Englert et al.

Galaxies with the faintest surface brightness are currently known only in the Local Group. Similar objects should exist beyond our vicinity and are crucial for understanding galaxy evolution, structure, and dark matter content, yet surveys have not reached the depth required to detect them systematically. We present a population of seven almost-dark galaxies identified in Data Preview 2 of the Rubin Legacy Survey of Space and Time. They surround M49 in the vicinity of the Virgo Cluster, and exhi…

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astro-ph.GAastro-ph.CO2026年9月17日

A High-Mass Size Deficit for Void Galaxies in the Complete SDSS DR7

Olivia Curtis, Bryanne McDonough, Tereasa G. Brainerd

We characterize how environment shapes the sizes, luminosity functions, and mass functions of galaxies in large-scale underdensities by comparing the NSA catalog of the Sloan Digital Sky Survey Data Release 7 with an identically selected TNG300 sample, both built with the void finding algorithm VoidFinder, and by assigning a local average underdensity contrast to each galaxy via a spherical top-hat smoothed density field approximation. Void galaxies have fainter characteristic magnitudes than th…

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astro-ph.SRastro-ph.GA2026年9月17日

Precise and Accurate Mass and Radius Measurements of Thirty Galactic Metal-Poor Stars in Detached Eclipsing Binaries

D. M. Rowan, K. Z. Stanek, C. S. Kochanek, Benjamin J. Fulton, Ilya Ilyin, Howard Isaacson, David V. Martin

Detached eclipsing binaries have long served as fundamental benchmarks for making direct comparisons with stellar models. By combining the light curve and radial velocity orbit of a detached eclipsing binary, precise masses and radii can be measured for both components. However, catalogs of eclipsing binaries are dominated by solar-metallicity stars. Here we characterize fifteen eclipsing binaries selected to have $[\rm{M/H}]\lesssim -0.5$ using TESS photometry, Gaia XP spectra, large spectrosco…

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astro-ph.EPastro-ph.SR2026年9月17日

Stellar companions sculpt hot Jupiter formation and spin-orbit evolution

Cheyanne Shariat, Kareem El-Badry, Songhu Wang, Xian-Yu Wang, Malena Rice, Jerry W. Xuan, David R. Ciardi

Stellar companions can drive hot-Jupiter (HJ) migration and spin-orbit misalignment, but their role in HJ formation remains uncertain. We construct a homogeneous census of resolved stellar companions to $147$ northern HJs with measured projected obliquities. We obtain uniform adaptive-optics imaging and combine these observations with {\it Gaia} common proper-motion pairs to identify 8 new companion candidates, bringing the \textit{observed} companion fraction to $71/147=48\%$. Modeling the full…

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astro-ph.GA2026年9月17日

Rubin LSST DP2 unveils almost-dark galaxies in the Virgo Cluster

Minh Ngoc Le, Johan H. Knapen, Željko Ivezić, Junais, Aaron Watkins, Dan S. Taranu, Pierre-Alain Duc, Anthony Englert et al.

Galaxies with the faintest surface brightness are currently known only in the Local Group. Similar objects should exist beyond our vicinity and are crucial for understanding galaxy evolution, structure, and dark matter content, yet surveys have not reached the depth required to detect them systematically. We present a population of seven almost-dark galaxies identified in Data Preview 2 of the Rubin Legacy Survey of Space and Time. They surround M49 in the vicinity of the Virgo Cluster, and exhi…

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physics.geo-phastro-ph.EPphysics.ao-ph2026年9月17日

Period-Inverted Blast-Radius Normalization for a Non-Ablating Hypersonic Reentry Source Using OSIRIS-REx Capsule Infrasound

Elizabeth A. Silber

Cylindrical blast wave theory relates infrasound from hypersonic sources to energy deposition through a characteristic blast radius R_0, yet the normalization constant k in the scaling R_0 = k (E_0/p_0)^(1/2) differs by up to 40% across the formulations examined here. This uncertainty affects period-based source characterization for elevated atmospheric sources relevant to infrasound monitoring. Using infrasound from the OSIRIS-REx Sample Return Capsule reentry on 24 September 2023, observed per…

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astro-ph.EPastro-ph.SR2026年9月17日

A Binary Flux Calibrator Reveals the Scientific Potential of Short-integration JWST MIRI Imaging to Directly Detect sub-Jupiter Exoplanets

Rachel Bowens-Rubin, Mary Anne Limbach, Alexander Venner, Kyle Franson, Emily K. Pass, Andrew Vanderburg, Kevin B. Stevenson

We report the direct imaging detection of a stellar companion to HD 101452 (HIP 56925; Gaia DR3 5384905720847544192), an A star historically used as an infrared flux calibrator. The companion was identified from an asymmetry in the stellar PSF using short-integration (<1 min), noncoronagraphic JWST MIRI imaging from 15 - 25.5$μ$m that was obtained as part of the absolute flux calibration program CAL 4496. We detect the stellar companion in four MIRI imaging filters at a projected separation of 1…

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astro-ph.EPastro-ph.SR2026年9月17日

A Binary Flux Calibrator Reveals the Scientific Potential of Short-integration JWST MIRI Imaging to Directly Detect sub-Jupiter Exoplanets

Rachel Bowens-Rubin, Mary Anne Limbach, Alexander Venner, Kyle Franson, Emily K. Pass, Andrew Vanderburg, Kevin B. Stevenson, Logan Pearce et al.

We report the direct imaging detection of a stellar companion to HD 101452 (HIP 56925; Gaia DR3 5384905720847544192), an A star historically used as an infrared flux calibrator. The companion was identified from an asymmetry in the stellar PSF using short-integration (<1 min), noncoronagraphic JWST MIRI imaging from 15 - 25.5$μ$m that was obtained as part of the absolute flux calibration program CAL 4496. We detect the stellar companion in four MIRI imaging filters at a projected separation of 1…

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astro-ph.GA2026年9月17日

Massive Galaxy Halos Contain Less Inner Dark Matter Than Predicted

Yu-Chen Wang, Yingjie Peng, Xiaohu Yang, Luis C. Ho, Dingyi Zhao, Jing Dou, Hao Fu, Zeyu Gao et al.

The mass profiles of galaxy halos encode how baryons reshape dark matter distribution, yet direct observational constraints across the full radial range remain scarce. Here we combine stellar kinematics from MaNGA, H I dynamical measurements from ALFALFA, and independently calibrated halo masses of SDSS groups to statistically reconstruct the mass distribution of central galaxies over nearly two orders of magnitude in radius. We demonstrate that H I data alone do not provide reliable total halo…

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astro-ph.EP2026年9月17日

An Updated Model for Epsilon Eridani b and Prospects for Imaging with the Roman Coronagraph

Jorge Llop-Sayson, Andre Fogal, James Mang, William Thompson, Clarissa R. Do 'O, Aniket Sanghi, Isabela G. Huckabee, Laurent Pueyo et al.

Epsilon Eridani b, the nearest known Jupiter analog, has its orbit and mass constrained from radial velocity (RV) and absolute astrometry, and its atmosphere from JWST/NIRCam imaging upper limits in Sanghi et al. 2026. Here we follow up that work with a self-consistent model of Epsilon Eridani b that treats all available data within a single Bayesian framework. We extend the RV data with new measurements, update the treatment of the astrometry data with a new model, and include the NIRCam observ…

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astro-ph.HE2026年9月17日

Radiation-Driven Magnetic Fields in Sub-Keplerian Accretion Flows: An Alternative to MRI

Mukesh Kumar Vyas, Asaf Pe'er

Large scale magnetic fields play a crucial role in shaping the dynamics and structure of the inner parts of accretion disks and the resulting jets from the vicinity of black holes and neutron stars. Currently, the primary mechanism considered for generating and amplifying large scale magnetic fields in accretion disks is the magneto-rotational instability (MRI). Here we show that non-conservative radiation fields provide a rapid and independent mechanism for generating and amplifying magnetic fi…

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astro-ph.IM2026年9月17日

Characterization of the CSST Survey Camera CCDs: I. basic electro-optical performance

Zun Luo, Hu Zhan, Youhua Xu, Qiuyan Luo, Yuhe Song, Fajun Li, Li Shao, Zhe Huang et al.

The Chinese Space-station Survey Telescope (CSST) is a flagship mission designed to carry out a large-area high-resolution multiband imaging and slitless spectroscopic survey over a decade. The survey's science drivers, ranging from precision cosmology to stellar astrophysics, impose stringent requirements on the performance of its focal plane detectors. This paper is the first in a series that present ground-based characterization of the 31 flight-model charge-coupled devices (CCDs) of the CSST…

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astro-ph.SR2026年9月17日

Oscillating dynamo models with a time-nonlocal $α$ effect

Günther Rüdiger, Manfred Schultz, Alfio Bonanno

The traditional $α$ effect is extended by the first temporal derivative, so that in turbulent flows the magnetic field entering the induction process is effectively sampled in the past. As a consequence, dynamo excitation becomes easier and cycle times are prolonged relative to solutions obtained from the local standard formulation. The temporal shape of the magnetic cycles is also modified, with rise times becoming shorter than decline times, so that the profiles acquire a characteristic ``sawt…

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astro-ph.GAastro-ph.SR2026年9月17日

Rotational spectroscopy and astronomical search of propane-1-thiol (CH3CH2CH2SH) and propane-2-thiol ((CH3)2CHSH)

Wentao Song, Assimo Maris, Victor M. Rivilla, Miguel Sanz-Novo, Izaskun Jimenez-Serra, Luca Evangelisti, Sonia Melandri

This study focuses on propanethiol (or propyl mercaptan, C3H7SH), a sulfur analogue of propanol and a key target for investigating interstellar sulfur chemistry. We report the laboratory rotational spectroscopic characterization of its two structural isomers, propane-1-thiol (1PT) and propane-2-thiol (2PT). For 1PT, experimental analysis led to the observation of three almost isoenergetic conformers, Aa,Ag and Gg, marking the first-time report of the latter. For 2PT, both the anti and gauche con…

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astro-ph.SRastro-ph.GA2026年9月17日

A large shell around the hypergiant VY Canis Majoris

D. P. K. Banerjee, V. Joshi, A. Evans, A. A. Djupvik, Ken Hall, F. -J. Hambsch, S. Sharma, G. Rangwal et al.

We report the detection of a remarkable shell around the red hypergiant VY CMa using data from the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx). The shell, which in projection on the plane of the sky appears as a ring, is almost circular in appearance. It has an external diameter of $\sim14'$ to $15'$, and is seen most clearly in the SPHEREx 7827A spectro-photometric image. Filaments, radially aligned with VY CMa, are seen to cut across t…

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astro-ph.SR2026年9月17日

Interferometric Survey of Stellar Parameters: Limb darkening study with the "Pipeline for Interferometric Measurements of Stars"

N. Ebrahimkutty, D. Mourard, P. Berio, O. Creevey, A. Domiciano de Souza, K. Lee, T. Morel, B. Plez et al.

Accurate and unbiased determination of stellar parameters is of importance in many astrophysical domains. We therefore present an improved method to estimate stellar parameters, based on interferometric observations and stellar atmosphere models, as well as spectroscopic and photometric data. The fundamental stellar parameters were estimated by fitting a model of intensity profiles to interferometric data over a large spectral window and combining them with spectroscopic and photometric observat…

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astro-ph.GAastro-ph.CO2026年9月17日

CosmoDyn: a semi-analytic post-processing framework for the dynamical evolution of compact stellar systems and black holes in cosmological simulations

Pierre Boldrini, Paola Di Matteo, David Katz, Laia Casamiquela, Chervin Laporte, Maxime Assuerus, Marco Montuori, Glenn van de Ven et al.

Although a large number of cosmological simulations are now publicly available, their spatial and mass resolutions remain insufficient to accurately follow the dynamics of compact stellar systems and black holes. A complementary approach is therefore required to exploit the cosmological assembly histories encoded in these simulations without rerunning them. We present CosmoDyn, an open-source Python framework that reconstructs time-dependent galactic environments from any cosmological simulation…

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hep-exastro-ph.SRphysics.ins-det2026年9月17日

After 60 years, here comes the Sun

Anatael Cabrera, Mark Chen, Stefano Dusini, Jeff Hartnell, Jorge Martín Camalich, Diana Navas Nicolás, Hiroshi Nunokawa, Aldo Serenelli et al.

For sixty years, the Sun served neutrino physics more than the reverse: its neutrinos established oscillations rather than probing the star itself. That is now changing. Reactor antineutrinos have pinned down the oscillation parameters governing solar-neutrino flavour conversion so precisely that the propagation-related uncertainty is becoming negligible -- closing the first of two abysses. Solar neutrinos can, at last, be turned on the Sun. Yet a second abyss remains: today's solar-neutrino det…

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astro-ph.GA2026年9月16日

CNO in Giant Metal-Poor Stars

Jannat Alazzawi

We present the chemical abundance analysis for elements carbon, nitrogen, oxygen and the carbon isotopic ratio in a sample of metal-poor stars selected from the RAVE survey based on their extreme radial velocities. Stellar parameters were derived using Gaia photometry and parallaxes, and elemental abundances were determined from high-resolution UVES spectra obtained at the ESO Very Large Telescope. The stars span a wide metallicity range (-2.9 ___ [Fe/H] ___ -1.2) and, for the majority of the sa…

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astro-ph.HEastro-ph.GA2026年9月16日

Studying the Intermittency of Magnetized Interstellar Medium by Synchrotron Polarization Intensity and its Gradient

Ru-Yue Wang, Jian-Fu Zhang

Based on synthetic polarization observations, we qualitatively investigate the intermittency of the magnetized interstellar medium (ISM) through synchrotron polarization intensity (SPI) and synchrotron polarization gradient (SPG). Three principal findings emerge from our analysis: (1) The intermittency of the magnetized ISM is strongly modulated by magnetization and compressibility, with pronounced modulation effects predominantly observed in regimes characterized by strong magnetization and hig…

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astro-ph.GAastro-ph.IM2026年9月16日

The Spitzer Data Fusion - A Far-Ultraviolet to Far-Infrared Multi-Wavelength Database in Spitzer Extragalactic Survey Fields

Mattia Vaccari

I present the Spitzer Data Fusion, a multi-wavelength photometric database providing far-ultraviolet to far-infrared flux measurements, together with photometric and spectroscopic redshifts, for 4.4 million IRAC-selected sources over 65\,deg$^2$ in eight of the most widely studied extragalactic survey fields. A companion product, the SERVS Data Fusion, provides 2.8 million sources over 18\,deg$^2$ selected from deeper Spitzer warm-mission imaging. Catalogs are band-merged with wavelength-depende…

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astro-ph.IM2026年9月16日

The Nancy Grace Roman Space Telescope Coronagraph Community Participation Program

Dmitry Savransky, Vanessa P. Bailey, Schuyler G. Wolff, Maxwell A. Millar-Blanchaer, Jason Wang, Lisa Altinier, Ramya Anche. Pierre Baudoz, Beth Biller et al.

In preparation for the operational phase of the Nancy Grace Roman Space Telescope, NASA has created the Coronagraph Community Participation Program (CPP) to prepare for and execute Coronagraph Instrument technology demonstration observations. The CPP is composed of 7 small, US-based teams, selected competitively via the Nancy Grace Roman Space Telescope Research and Support Participation Opportunity, members of the Roman Project Team, and international partner teams from ESA, JAXA, CNES, and the…

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astro-ph.SR2026年9月16日

A homogeneous analysis of archival and new low-resolution spectra of YZ Cancri

Zhibin Dai, Lihuan Yu, Jiao Li, Xuefei Chen, Zhanwen Han

YZ Cancri is an SU UMa-type dwarf nova with sparse and heterogeneous optical spectroscopy. We present a homogeneous analysis of archival outburst-related spectra and seven new low-resolution quiescent spectra. We consistently characterize the Balmer, He I, Fe II, O I, and occasional He II and Bowen features, and assess which state-dependent differences are robustly supported. We applied a common continuum-normalization and line-measurement procedure, measuring equivalent widths, integrated line…

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astro-ph.SR2026年9月16日

The emergence of a [WC] star in Sakurai's object

W. Marcolino, P. A. M. van Hoof, V. C. Maria, H. Todt, G. C. Van de Steene, J. A. Toalá, S. Kimeswenger, M. Hajduk et al.

Sakurai's object provides a rare opportunity to observe stellar evolution on human timescales. Since its born-again event and detection in 1996, its evolution has been extensively monitored, and recent optical spectroscopy has suggested the emergence of [WR]-type emission features. In this Letter, we present a secure spectroscopic identification of its central star based on new VLT/FORS2 observations and NLTE expanding atmosphere models. Several observed emission lines arise in a [WR]-type stell…

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astro-ph.IM2026年9月16日

Supporting users in their observation preparation - the ESO ObsPrep tool

Monika G. Petr-Gotzens, Vincenzo Forchi, Andrea Mehner, Thomas Bierwirth, John Pritchard, Ahmed M. Khan, Olivier R. Hainaut, Kevin Knecht et al.

Ground based observatories are experiencing significant technological advances and telescopes are getting equipped with highly complex instruments to enable cutting-edge astronomical research. The increasing complexity of such instruments displays a challenge to their users when they want to plan and prepare specific observation programmes, that often request to define large amount of detailed instrument-specific information. Therefore, at ESO we developed an Observation Preparation tool (in sho…

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astro-ph.IMastro-ph.EPcs.AI2026年9月16日

Reinforcement learning for post-coronagraphic wavefront control

Manuela Castañeda-Medina, Yann Gutierrez, Johan Mazoyer, Baptiste Abeloos, Laurent Mugnier, Olivier Herscovici-Schiller

Direct imaging of exoplanets is limited by the extreme contrast between the star and the planets, which is mitigated using a coronagraph. However, optical aberrations cause starlight leakage through the coronagraph, producing speckles that obscure the planetary signal. Achieving the required contrast levels demands wavefront control with subnanometric precision. Deep reinforcement learning offers a promising alternative to traditional focal-plane wavefront control techniques by enabling adaptive…

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gr-qcastro-ph.HEhep-th2026年9月16日

Shadow and Polarized Images of Schwarzschild-MOG Black Hole Illuminated by Thick Accretion Disk

Cheng Hu, Huan Ye, Hong Lei, Zi-Chao Lin

Recent EHT polarimetric observations provide a powerful probe of near-horizon physics and modified gravity. We investigate the shadow and polarization images of a static Schwarzschild-MOG black hole illuminated by geometrically thick, optically thin accretion flows. Adopting a phenomenological model and the Hou disk model, and solving null geodesics and relativistic radiative transfer, we study how the MOG parameter, inclination angle, anisotropic synchrotron emission, and flow geometry affect t…

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astro-ph.SR2026年9月16日

Spectral classification of OB-type stars using tree-based ensemble methods and evaluation of their explainability

J. E. Gonzales, S. Simón-Díaz, S. Cuellar, J. A. Conejero, G. Holgado, A. de Burgos

[Abridged] The advent of large-scale spectroscopic surveys will deliver tens of thousands of spectra of blue massive stars. This data volume renders traditional spectral classification techniques increasingly impractical. We aim to develop a robust ML framework for the automated spectral classification of massive OB stars by assessing several tree-based ensemble algorithms. Using a large catalog of high-quality optical spectra of OB stars, we design 3 hierarchical experiments of increasing compl…

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astro-ph.GAastro-ph.CO2026年9月16日

Signatures of dark subhaloes in dwarf spheroidal galaxies: II. Transient and localised kinematic features

Eduardo Vitral, Jorge Penarrubia, Roeland P. van der Marel, Matthew G. Walker

We use controlled N-body simulations to investigate whether dark matter subhaloes leave detectable signatures in the internal kinematics of dwarf spheroidal galaxies. At each snapshot, we fit a velocity distribution function to stellar line-of-sight velocities and proper motions, construct normalised residual fields for the projected velocity components, and analyse their power-spectra. We show that subhalo encounters generate a plethora of kinematic features. Amongst the most prominent are rota…

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astro-ph.GA2026年9月16日

Challenging the archetypal intermittent radio galaxy J0111+3906. New insights from optical GTC/OSIRIS and radio VLA and LOFAR observations

M. Orienti, J. A. Acosta-Pulido, E. De Rubeis, C. Stanghellini, M. Bondi, F. D'Ammando, L. Coccato, I. Alemán-Martín et al.

We present results on new optical Gran Telescopio CANARIAS OSIRIS+ spectroscopy and radio Very Large Array (VLA) observations at 360 MHz of the optical object behind the radio emission 20 arcseconds east of the archetypal restarted compact symmetric object (CSO) J0111+3906. The optical counterpart is a post-starburst galaxy at redshift $z$ = 1.042, ruling out any physical relation between this object and the CSO radio galaxy J0111+3906 at redshift $z$ = 0.668. The radio emission is therefore not…

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