Sazuna/UAT_keywords huggingface dataset:
Escaping Helium and a Highly Muted Spectrum Suggest a Metal-enriched Atmosphere on Sub-Neptune GJ 3090 b from JWST Transit Spectroscopy. Sub-Neptunes, the most common planet type, remain poorly understood. Their atmospheres are expected to be diverse, but their compositions are challenging to determine, even with JWST. Here, we present the first JWST spectroscopic study of the warm sub-Neptune GJ 3090 b (2.13 R⊕, Teq,A = 0.3 ∼ 700 K), which orbits an M2V star, making it a favorable target for atmosphere characterization. We observed four transits of GJ 3090 b: two each using JWST NIRISS/SOSS and NIRSpec/G395H, yielding wavelength coverage from 0.6 to 5.2 μm. We detect the signature of the 10833 Å metastable helium triplet at a statistical significance of 5.5σ with an amplitude of 434 ± 79 ppm, marking the first such detection in a sub-Neptune with JWST. This amplitude is significantly smaller than predicted by solar-metallicity forward models, suggesting a metal-enriched atmosphere that decreases the mass-loss rate and attenuates the helium feature amplitude. Moreover, we find that stellar contamination, in the form of the transit light source effect, dominates the NIRISS transmission spectra, with unocculted spot and faculae properties varying across the two visits separated in time by approximately 6 months. Free retrieval analyses on the NIRSpec/G395H spectrum find tentative evidence for highly muted features and a lack of CH4. These findings are best explained by a high-metallicity atmosphere (&gt;100× solar at 3σ confidence for clouds at ∼μbar pressures) using chemically consistent retrievals and self-consistent model grids. Further observations of GJ 3090 b are needed for tighter constraints on the atmospheric abundances and to gain a deeper understanding of the processes that led to its potential metal enrichment.

Keywords: Exoplanet atmospheric composition , Exoplanets, Transmission spectroscopy, James Webb Space Telescope, Exoplanet atmospheres
High-resolution Observations of a Small-scale Cancellation Nanoflare: Supporting Evidence for the Cancellation Nanoflare Model. An analytical cancellation nanoflare model has recently been established to show the fundamental role that ubiquitous small-scale cancellation nanoflares play in solar atmospheric heating. Although this model is well supported by simulations, observational evidence is needed to deepen our understanding of cancellation nanoflares. We present observations of a small-scale cancellation nanoflare event, analyzing its magnetic topology evolution, triggers, and physical parameters. Using coordinated observations from the Solar Dynamics Observatory and Goode Solar Telescope, we identify a photospheric flow-driven cancellation event with a flux cancellation rate of ∼1015 Mx s‑1 and a heating rate of 8.7 × 106 erg cm‑2 s‑1. The event shows the characteristic transition from π-shaped to X-shaped magnetic configuration before the formation of a 2″ current sheet, closely matching model predictions. This event provides critical observational support for the cancellation nanoflare model and its role in solar atmospheric heating.

Keywords: Solar magnetic fields, Magnetohydrodynamics, Solar chromosphere, Solar magnetic reconnection
Reconnection Nanojets in an Erupting Solar Filament with Unprecedented High Speeds. Solar nanojets are small-scale jets generated by component magnetic reconnection, characterized by collimated plasma motion perpendicular to the reconnecting magnetic field lines. As an indicator of nanoflare events, they are believed to play a significant role in coronal heating. Using high-resolution extreme-ultraviolet imaging observations from the Extreme Ultraviolet Imager on board the Solar Orbiter mission, we identified 27 nanojets in an erupting filament on 2024 September 30. They are potentially associated with the untwisting of magnetic field lines of the filament. Most nanojets exhibit velocities around 450 km s‑1, with the fastest reaching approximately 800 km s‑1, significantly higher than previously reported but comparable to the typical coronal Alfvén speed. To our knowledge, these are the highest speeds ever reported for small-scale jets (less than ∼1 Mm wide) in the solar atmosphere. Our findings suggest that these nanoflare-type phenomena can be more dynamic than previously recognized and may contribute to the energy release process of solar eruptions and the heating of coronal active regions.

Keywords: The Sun, Solar corona, Solar magnetic reconnection, Solar filament eruptions
The Effect of Turbulence on the Angular Momentum of the Solar Wind. The transfer of a star's angular momentum to its atmosphere is a topic of considerable and wide-ranging interest in astrophysics. This Letter considers the effect of kinetic and magnetic turbulence on the solar wind's angular momentum. The effects are quantified in a theoretical framework that employs Reynolds-averaged mean field magnetohydrodynamics, allowing for fluctuations of arbitrary amplitude. The model is restricted to the solar equatorial (r–ϕ) plane with axial symmetry, which permits the effect of turbulence to be expressed in analytical form as a modification to the classic E. J. Weber &amp; L. Davis theory, dependent on the r, ϕ shear component of the Reynolds stress tensor. A solar wind simulation with turbulence transport modeling and Parker Solar Probe observations at the Alfvén surface are employed to quantify this turbulent modification to the solar wind's angular momentum, which is found to be ∼3%–10% and tends to be negative. Implications for solar and stellar rotational evolution are discussed.

Keywords: Solar rotation, Interplanetary turbulence, Solar wind, Stellar winds, Solar corona, Solar evolution
Squeezing Full-shape Dynamical Dark Energy Constraints with Galaxy Alignments. Recent 2σ–4σ deviations from the cosmological constant   suggest that dark energy (DE) may be dynamical, based on baryon acoustic oscillations and full-shape galaxy clustering (FS GC) analyses. This calls for even tighter DE constraints to narrow down its true nature. In this Letter, we explore how galaxy intrinsic alignments (IA) can enhance the FS GC–based DE constraints, using Fisher forecasts on various extensions of dynamical DE models, including scenarios with curvature, massive neutrinos, and modified gravity. Incorporating IA improves the DE figure of merit by 42%–57% and tightens the primordial power spectrum amplitude constraints by 17%–19%. Our findings highlight IA's potential as a valuable cosmological probe complementary to GC.

Keywords: Astrostatistics strategies, Dark energy
High Optical-to-X-Ray Polarization Ratio Reveals Compton Scattering in BL Lacertae's Jet. Blazars, supermassive black hole systems with highly relativistic jets aligned with the line of sight, are the most powerful long-lived emitters of electromagnetic emission in the Universe. We report here on a radio-to-gamma-ray multiwavelength campaign on the blazar BL Lacertae with unprecedented polarimetric coverage from radio to X-ray wavelengths. The observations caught an extraordinary event on 2023 November 10–18, when the degree of linear polarization of optical synchrotron radiation reached a record value of 47.5%. In stark contrast, the Imaging X-ray Polarimetry Explorer found that the X-ray (Compton scattering or hadron-induced) emission was polarized at less than 7.4% (3σ confidence level). We argue here that this observational result rules out a hadronic origin of the high-energy emission and strongly favors a leptonic (Compton scattering) origin, thereby breaking the degeneracy between hadronic and leptonic emission models for BL Lacertae and demonstrating the power of multiwavelength polarimetry to address this question. Furthermore, the multiwavelength flux and polarization variability, featuring an extremely prominent rise and decay of the optical polarization degree, is interpreted for the first time by the relaxation of a magnetic "spring" embedded in the newly injected plasma. This suggests that the plasma jet can maintain a predominant toroidal magnetic field component parsecs away from the central engine.

Keywords: Non-thermal radiation sources, Active galaxies, BL Lacertae objects, Relativistic jets
The Giant Eruption in Solar Cycle 25 Caused by Collisional Shearing. On 2024 October 3, solar active region (AR) 13842 produced an X9.0 flare, which is the largest one in Solar Cycle 25 so far. Our study is to answer the question of what process caused this flare. Based on the magnetic field observations from the Solar Dynamics Observatory (SDO), we find that the nonconjugated sunspots of opposite polarities of the AR core region underwent a persistent collision process with strong shearing motions. Moreover, flux cancellation was observed at the collision region, e.g., 1021 Mx of unsigned flux canceled at the local area within 2 hr, suggesting the occurrence of collisional shearing. Meanwhile, a collisional polarity inversion line (PIL) was produced in the AR core region as a result of the collision of the nonconjugated polarities during flux emergence. The SDO/Atmospheric Imaging Assembly extreme-ultraviolet observations show that two flux ropes formed above the PIL. Due to the photospheric magnetic field evolution, the two flux ropes destabilized and then erupted simultaneously. Using nonlinear force-free field modeling, we notice that there were three flux ropes at the PIL, including the two ropes mentioned above and another unobserved one. We suggest that the formation of flux ropes that carry massive accumulated free energy by the collisional shearing process and the eruption of the flux rope system are responsible for the giant flare in Solar Cycle 25.

Keywords: Solar atmosphere, Solar flares, Sunspots, Solar magnetic fields, Solar activity
The Critical Role of LIGO-India in the Era of Next-generation Observatories. We examine the role of LIGO-India in facilitating multimessenger astronomy in the era of next-generation observatories. A network with two L-shaped Cosmic Explorer (CE) detectors and one triangular Einstein Telescope (ET) would precisely localize nearly the entire annual binary neutron star (NS) merger population up to a redshift of 0.5—over 10,000 events would be localized within 10 deg2, including approximately 150 events within 0.1 deg2. Luminosity distance would be measured to within 10% for over 9000 events and within 1% for ∼100 events. Surprisingly, replacing the 20 km CE detector with LIGO-India operating at A♯ sensitivity (I♯) yields a nearly identical performance. The factor-of-5 shorter arms are offset by a fourfold increase in baseline relative to a second CE in the US, preserving localization accuracy, with over 9000 events within 10 deg2 and ∼90 events within 0.1 deg2. This configuration detects ∼6000 events with luminosity distance uncertainties under 10%, including ∼50 with under 1%. Both networks provide   early-warning detections up to 10 minutes before merger, with localization areas ≤10 deg2. While I♯ enables excellent localization and early warnings, its shorter arms and narrower sensitivity band would limit its reach for other science goals, such as detecting Population III binary black hole mergers at z ≳ 10, NS mergers at z ∼ 2, or constraining cosmological parameters.

Keywords: Neutron stars, Gravitational wave detectors, Compact binary stars, Gravitational wave astronomy, Compact objects
Identifying LL Chondrite Near-Earth Asteroids Using LL Chondrite Reflectance Spectra. Most near-Earth objects are thought to originate from the collisional fragments of the main asteroid belt. One question that remains to be resolved is the proportion of near-Earth objects sampling the core area material of the parent body to the outer layers. In this study, we developed a method to determine the petrologic type of ordinary chondrite parent bodies based on reflectance spectroscopy. We also calculated the petrologic type of asteroid (25143) Itokawa, which is consistent with the returned samples from the JAXA Hayabusa mission. Finally, we calculate the petrologic type of 28 LL near-Earth asteroids. Our results show that the surface material of most LL chondrite near-Earth asteroids is of petrologic grade higher than 4. The ratio of LL chondrite near-Earth asteroids with high petrologic type (5 and 6) to LL chondrite near-Earth asteroids with low petrologic type is 0.79. This also means that LL chondrite near-Earth asteroids may originate primarily from the core area of the main belt parent body or bodies.

Keywords: Near-Earth objects, Asteroids, Planetary thermal histories
Mars Gravity Field Determination Using Tianwen-1 Orbiter Tracking Data. The Martian gravity field is a key data set for studying the internal structure of Mars. For this purpose, we processed all the two-way Doppler tracking data of the Tianwen-1 orbiter from 2021 June to 2024 October and determined a new degree and order 80 Martian static gravity field model, TW80. The Tianwen-1 orbiter tracking data show high accuracy, with approximately 90% of arcs achieving an rms of residuals of less than 0.1 mm s–1. We evaluated this model in terms of gravity anomaly errors, gravity/topography correlation, and orbit determination performance. The TW80 gravity field model reaches a global resolution of degree and order 74, corresponding to a spatial resolution of approximately 140 km. The rms of the gravity anomaly errors is approximately 35.8 mGal, with notably smaller errors near the south pole region in the southern hemisphere and larger errors in mid- and low-latitude regions. The TW80 model shows a high correlation with topography and is consistent with the MRO120D gravity field model up to degree 40. Due to the highly elliptical orbit geometry, the orbit determination performance of the TW80 model for the Tianwen-1 orbiter is comparable to that of the MRO120D model, with radial differences less than 100 m and total position differences less than 500 m. Further improvements in orbit determination accuracy will focus on precise modeling of orbital maneuvers and the solar radiation pressure model, as well as extending the tracking duration of individual arcs.

Keywords: Gravitational fields, Mars, Orbit determination
XRISM Forecast for the Coma Cluster: Stormy, with a Steep Power Spectrum. The XRISM Resolve microcalorimeter array measured the velocities of hot intracluster gas at two positions in the Coma galaxy cluster:  3'×3'  squares at the center and at 6 '  (170 kpc) to the south. We find the line-of-sight velocity dispersions in those regions to be σz = 208 ± 12 km s‑1 and 202 ± 24 km s‑1, respectively. The central value corresponds to a 3D Mach number of M = 0.24 ± 0.015 and a ratio of the kinetic pressure of small-scale motions to thermal pressure in the intracluster plasma of only 3.1% ± 0.4%, at the lower end of predictions from cosmological simulations for merging clusters like Coma, and similar to that observed in the cool core of the relaxed cluster A2029. Meanwhile, the gas in both regions exhibits high line-of-sight velocity differences from the mean velocity of the cluster galaxies, Δvz = 450 ± 15 km s‑1 and 730 ± 30 km s‑1, respectively. A small contribution from an additional gas velocity component, consistent with the cluster optical mean, is detected along a sight line near the cluster center. The combination of the observed velocity dispersions and bulk velocities is not described by a Kolmogorov velocity power spectrum of steady-state turbulence; instead, the data imply a much steeper effective slope (i.e., relatively more power at larger linear scales). This may indicate either a very large dissipation scale, resulting in the suppression of small-scale motions, or a transient dynamic state of the cluster, where large-scale gas flows generated by an ongoing merger have not yet cascaded down to small scales.

Keywords: Galaxy clusters, High resolution spectroscopy, Intracluster medium, Coma Cluster
Modeling Galaxies in the Early Universe with Supernova Dust Attenuation. Supernovae (SNe) may be the dominant channel by which dust grains accumulate in galaxies during the first Gyr of cosmic time as formation channels important for lower-redshift galaxies, e.g., asymptotic giant branch stars and grain growth, may not have had sufficient time to take over. SNe produce fewer small grains, leading to a flatter attenuation law. In this work, we fit observations of 138 spectroscopically confirmed z &gt; 6 galaxies adopting standard spectral energy distribution (SED) modeling assumptions and compare standard attenuation law prescriptions to a flat attenuation law. Compared to SMC dust, flat attenuation close to what may be expected from dust produced in SNe yields up to 0.5 mag higher AV and 0.4 dex larger stellar masses. It also finds better fits to the rest-frame UV photometry with lower  χUV2 , allowing the observed UV luminosities taken from the models to be fainter by 0.2 dex on average. The systematically fainter observed UV luminosities for fixed observed photometry could help resolve current tension between the ionizing photon production implied by JWST observations and the redshift evolution of the neutral hydrogen fraction. Given these systematic effects and the physical constraint of cosmic time itself, fairly flat attenuation laws that could represent the properties of dust grains produced by SNe should be a standard consideration in fitting to the SEDs of z &gt; 6 galaxies.

Keywords: Interstellar dust, James Webb Space Telescope, High-redshift galaxies, Galaxy evolution
Galactic Accelerations from the GD-1 Stream Suggest a Tilted Dark Matter Halo. Cold dark matter halos are expected to be triaxial and often tilted relative to the stellar disk. Stellar streams provide a sensitive tracer of the Milky Way's halo shape though models for the Galactic potential are typically limited to simple, symmetric functional forms. Here, we measure the Galactic acceleration field along the GD-1 stream using a direct differentiation of the stream's track in phase space. Using a fully data-driven catalog of stream members from Gaia, Sloan Digital Sky Survey, LAMOST, and DESI, we map the stream in 6D phase space. We fit splines to the stream track and infer cylindrical acceleration components  aR=‑2.5±0.10.2 , az = ‑1.8 ± 0.1, and aϕ = 0.2 ± 0.1 km s‑1 Myr‑1 at (R, z, ϕ) = (11.9 kpc, 7.3 kpc, 171 .° 1). We measure mass enclosed within 14 kpc of 1.4 ± 0.1 × 1011 M⊙ and z-axis density flattening of  qρ,z=0.81±0.030.06 , both consistent with previous estimates. However, we find a 2σ deviation from an axisymmetric acceleration field, which can be explained by a triaxial dark matter halo with axis ratios 1:0.75:0.70. The major axis of the halo is consistent with a tilt of 18° above the Galactic plane in the direction of the Sun. The magnitude and direction of the tilt are consistent with measurements of the stellar halo from Gaia and the Hectochelle in the Halo at High Resolution survey. A tilted triaxial halo has important consequences for orbit-integration-based studies of the Galaxy and can be further tested by deriving acceleration constraints from multiple streams.

Keywords: Stellar streams, Galaxy mass distribution, Milky Way dynamics, Dark matter
The Striated Solar Photosphere Observed at <inline-formula> <mml:math><mml:mn>0</mml:mn><mml:mover><mml:mrow><mml:mi>.</mml:mi></mml:mrow><mml:mrow><mml:mi>″</mml:mi></mml:mrow></mml:mover><mml:mn>03</mml:mn></mml:math> </inline-formula> Resolution. Striated granular edges observed in the solar photosphere represent one of the smallest-scale phenomena on the Sun. They arise from the interaction of strongly coupled hydrodynamic, magnetic, and radiative properties of the plasma. In particular, modulations in the photospheric magnetic field strength cause variations in density and opacity along the line of sight, leading to their formation. Therefore, the striation patterns can be used as valuable diagnostics for studying the finest-scale structure of the photospheric magnetic field. The Daniel K. Inouye Solar Telescope (DKIST) allows observations of the solar atmosphere with a spatial resolution of better than 0 .″ 03 with its current instrumentation. We analyze images acquired with the Visible Broadband Imager using the G-band channel to investigate the characteristics of fine-scale striations in the photosphere and compare them with state-of-the-art radiation-MHD simulations at similar spatial resolution. Both observed and synthetic images reveal photospheric striae with widths of approximately 20‑50 km, suggesting that at least 4 m class solar telescopes are necessary to resolve this ultrafine structure. Analysis of the numerical simulations confirms that the striation observed in the filtergrams is associated with spatial variations in photospheric magnetic flux concentrations, which cause shifts in the geometrical height where the emergent intensity forms. Some fine-scale striations in the synthetic images originate from magnetic field variations of approximately 100 G, resulting in Wilson depressions as narrow as 10 km. This suggests that DKIST G-band images can trace the footprints of magnetic field variations and Wilson depressions at a similar scale.

Keywords: Solar photosphere, Ground-based astronomy, Radiative transfer, Ground telescopes, Magnetohydrodynamical simulations
First Detections of PN, PO, and PO<SUP>+</SUP> toward a Shocked Low-mass Starless Core. Phosphorus is a key element that plays an essential role in biological processes important for living organisms on Earth. The origin and connection of phosphorus-bearing molecules to early solar system objects and star-forming molecular clouds is therefore of great interest, yet there are limited observations throughout different stages of low-mass (M &lt; a few solar masses) star formation. Observations from the Yebes 40 m and IRAM 30 m telescopes detect for the first time in the 7 mm, 3 mm, and 2 mm bands multiple transitions of PN and PO, as well as a single transition of PO+, toward a low-mass starless core. The presence of PN, PO, and PO+ is kinematically correlated with bright SiO(1–0) emission. Our results reveal not only that shocks are the main driver of releasing phosphorus from dust grains and into the gas phase but that the emission originates from gas not affiliated with the shock itself but quiescent gas that has been shocked in the recent past. From radiative transfer calculations, the PO/PN abundance ratio is found to be  3.1‑0.6+0.4 , consistent with other high-mass and low-mass star-forming regions. This first detection of PO+ toward any low-mass star-forming region reveals a PO+/PO ratio of  0.0115‑0.0009+0.0008 , a factor of 10 lower than previously determined from observations of a Galactic center molecular cloud, suggesting its formation can occur under more standard Galactic cosmic-ray ionization rates. These results motivate the need for additional observations that can better disentangle the physical mechanisms and chemical drivers of this precursor of prebiotic chemistry.

Keywords: Submillimeter astronomy, Shocks, Star formation, Astrochemistry