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Stellar wind driven Alfvén wing dynamics in planetary and exoplanetary magnetospheres
(Frontiers Media SA, 2026-10-16)
Gupta, Sakshi
;
Basak, Arnab
;
Nandy, Dibyendu
Magnetized obstacles embedded within a plasma flow generate magnetohydrodynamic structures known as Alfvén wings, which act as primary conduits for the transfer of momentum and energy between the body and the surrounding medium. This study employs three-dimensional resistive magnetohydrodynamic simulations to explore how these wings and the magnetosphere respond to diverse stellar wind conditions. Our results, gleaned from a large number of simulations spanning a wide range of stellar wind speed and magnetic field–and planetary dipole field–show that the global magnetospheric configuration is highly sensitive to the upstream Alfvén Mach number. We find that increasing stellar wind speed leads to a systematic closure and narrowing of Alfvén wing structures, while stronger stellar magnetic fields facilitate their opening. Analysis of the Alfvén wing morphology demonstrates a distinct dependence of wing opening angle on stellar wind speed, with internal wing analysis showing a reduction in plasma velocity and significant magnetic-flux accumulation. Our results exhibit a clear interdependence between the day-side magnetopause stand-off distance and the night-side magnetotail current sheet length. We find a linear scaling between the magnetotail dynamics and upstream forcing parameters. This study bridges the gap between solar system observations and (exo)planetary systems by demonstrating how Earth-like magnetospheres might transform into wing-dominated configurations during extreme stellar events or within the sub-Alfvénic regimes of close-in (exo)planets. Our findings can aid the interpretation of Alfvén wing signatures in observational data and enhance our understanding of how (exo)planetary magnetospheres respond to dynamic stellar wind forcing.
MSA-3D: Uncovering Weak Active Galactic Nuclei and Resolved Outflows in Disguise in z ∼ 1 Star-forming Galaxies
(American Astronomical Society, 2026-10-29)
Roy, Namrata
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Henry, Alaina
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Jones, Tucker
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Barisic, Ivana
;
Sanders, Ryan L
We present spatially resolved rest-optical spectroscopy of 38 star-forming galaxies at 0.5 < z < 1.5 from the JWST/NIRSpec Micro-Shutter Assembly (MSA)-3D survey, which employs a slit-stepping strategy to build integral field unit–like data cubes with a spatial sampling of ∼0.1. We map emission-line morphology, excitation, and kinematics of the warm-ionized gas using [N II]/Hα, [S II]/Hα, and [O III]/Hβ. Relative to z ∼ 0 galaxies at fixed stellar mass, our sources show systematically lower [N II]/Hα and [S II]/Hα and elevated [O III]/Hβ, consistent with harder radiation fields and lower metallicities. Radially, [O III]/Hβ profiles are typically flat or mildly positive, whereas [N II]/Hα also remains flat or declines outward, mirroring metallicity trends. On kiloparsec scales, we find a strong positive correlation between [N II]/Hα and velocity dispersion (σ), linking local excitation to turbulent or shock-driven kinematics. Six galaxies (∼16% of the sample) host spatially localized regions with elevated [N II]/Hα, high EW(Hα), and Vrms V + > 250 km s 2 2 1, indicative of weak active galactic nucleus (AGN) activity, shocks, or outflows. For these candidates, we infer modest warm-ionised outflow rates of 1−4 M⊙ yr−1 and kinetic powers ∼0.1%−1% of the AGN bolometric luminosity (from central [O III] or Hα). These values place our sample at the low-energy tail of known AGN-driven outflows yet in continuity with Mout–LAGN scaling relations across 0 < z < 6. A completeness assessment shows MSA-3D is sensitive to AGN with LAGN ≳ 1043 erg s−1, underscoring both the promise and current limitations of detecting weak AGN activity in distant galaxies with resolved spectroscopy.
Observations of the 21 cm Hi line from the milky way galaxy using pyramidal horn radio telescope
(Springer Nature, 2026-10-13)
Bhattacharjee, Kaustav
;
Grover, Himanshu
;
Arumugam, P
We present the design, implementation, and operation of a pyramidal horn radio telescope built for detecting the Galactic 21 cm neutral hydrogen line emission. The system employs a Software-Defined Radio (SDR) based pipeline to obtain drift-scan observations, which were calibrated and processed to generate Hi sky maps, a Galactic rotation curve and spiral arm features. This demonstrates that this low-cost system is effective both for educational purposes and scientific exploration of Galactic structure at radio frequencies.
Detection of the Cosmological 21 cm Signal in Autocorrelation at z ∼ 1 with the Canadian Hydrogen Intensity Mapping Experiment
(American Astronomical Society, 2026-09-28)
Amiri, Mandana
;
Bandura, Kevin
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Chakraborty, Arnab
;
Cliche, Jean-François
;
Dobbs, Matt
We present the first detection of the cosmological 21 cm intensity mapping signal in autocorrelation at z ∼ 1 with the Canadian Hydrogen Intensity Mapping Experiment (CHIME). Using 94 nights of observation, we have measured the 21 cm auto power spectrum over a frequency range of 608.2–707.8 MHz (z = 1.34–1.01) at 0.4 h Mpc−1 ≲ k ≲ 1.5 h Mpc−1, with a detection significance of 12.4σ. Our analysis employs significant improvements to the CHIME data processing pipeline compared to previous work, including novel radio frequency interference detection and masking algorithms, achromatic beamforming techniques, and foreground filtering before time averaging to minimize spectral leakage. We establish the robustness and reliability of our detection through a comprehensive suite of validation tests. We also measure the 21 cm signal in two independent sub-bands centered at z ∼ 1.08 and z ∼ 1.24 with detection significance of 8.6σ and 9.1σ, respectively. We briefly discuss the theoretical interpretation of these measurements in terms of a power spectrum model, deferring the details to a companion paper. This auto power spectrum detection demonstrates CHIME’s capability to probe large-scale structure through 21 cm intensity mapping without reliance on external galaxy surveys.
Columnar self-assembly as a design strategy for naphthophenanthridine-based blue OLEDs
(Royal Society of Chemistry (RSC), 2026-07-30)
Bhat S, Vanishree
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Danjou, Pierre-Edouard
;
Kumar, Anil
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Duponchel, Benoit
;
Depriester, Michael
Columnar materials have lately emerged as promising materials for organic light-emitting diodes (OLEDs) owing to their unidirectional charge transport and self-assembly characteristics. In the present investigation, we report the synthesis of naphthophenanthridine-based columnar dimers with varying peripheral alkyl chain lengths (CnH2n+1; n = 4, 8, and 12), emphasising a strategic design of materials for blue OLEDs. Polarised optical microscopy and X-ray diffraction studies reveal that the dimers exhibited a columnar soft-crystalline phase. This behaviour can be ascribed to the strong π-conjugation in the naphthophenanthridine, which facilitates the rigid columnar aggregation. Exhibiting charge-carrier mobility of the order of 10−5 cm2 V−1 s−1, and favourable emission characteristics, these dimers are appropriate for light-emitting applications. Using one of the homologs, blue OLEDs have been fabricated, which demonstrated an external quantum efficiency of 2.2% and a maximum luminance of 1153 cd m−2. The moderate device efficiency is attributed to the relatively deep HOMO level and suboptimal charge balance, highlighting opportunities for further molecular and device engineering to elevate OLED performance.

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