Abstract Using the MillenniumTNG hydrodynamical simulation (MTNG) and cosmic filaments identified with the \textsc{DisPerSE} algorithm, we investigate how filament proximity affects galaxy clustering and the galaxy--halo connection. At $z=0$, both halos and galaxies closer to filaments show stronger clustering, with the effect being strongest for low-mass systems. The environmental dependence of the halo occupation distribution (HOD), which measures the average number of galaxies occupying halos of a given mass, is driven mainly by satellites: at fixed stellar mass, halos near filaments host systematically more satellites than halos farther away, while the average occupation of central galaxies varies much less with filament proximity. At fixed halo mass, halos closer to filaments have higher conditional stellar mass function (CSMF) amplitudes, meaning that they host more galaxies at a given stellar mass, but the peak stellar mass of the central CSMF remains nearly unchanged across environments. Consistently, the mean stellar--halo mass relation (SHMR) of central galaxies depends only weakly on filament proximity. Extending the analysis to $z=1$, 2, and 4, we find that the relative environmental contrast in the HOD is stronger at high redshifts and becomes weaker toward low redshifts, whereas the SHMRs in near- and far-filament environments remain similar at all redshifts. These results show that filament proximity leaves a clear imprint on clustering and the number of galaxies hosted by halos, but a much weaker imprint on the mean stellar-mass growth of central galaxies.

We present an observational study of the kinematic coherence between satellite orbital planes and the cosmic web. Using the SDSS DR12 galaxy sample combined with the Bisous filament catalogue, we investigate whether the orbital motion of satellites preserves the memory of filamentary accretion. For each satellite system, we define a projected orbital-normal vector using galaxy sky positions and line-of-sight velocity offsets. By measuring the angle θ between this vector and the local projected filament direction, we detect a distinctive preferred orientation: satellite orbital planes tend to contain or lie parallel to the filament axis. This signal deviates from the isotropic expectation at a high significance level of 12.8 σ . The strength of this kinematic connection depend strongly on environment and host properties. The preference for orbital planes to track the filament direction is most pronounced for groups in close distance to the filament spine and for more massive hosts. Conversely, at intermediate distances from the filament and at large group-centric radii, the signal reverses, indicating a tendency for orbital planes to be oriented perpendicular to the filament. Our findings provide direct observational evidence for the two-phase model of filamentary accretion, where a transition from initial perpendicular collapse toward the filament spine to subsequent parallel streamwise infall into dark matter haloes governs the orientation of satellite orbital angular momentum and galaxy spin. The observed transition may further trace the characteristic radial scale of filaments, offering a dynamical perspective on the internal structure and assembly of the cosmic filament.

The James Webb Space Telescope (JWST) has revolutionized the characterization of exoplanetary atmospheres, offering unprecedented sensitivity to probe their chemical and physical properties. Recently, a growing trend has emerged to obtain atmospheric information directly from pixel-level planetary spectra. In this work, we re-analyzed the WASP-18b NIRISS/SOSS dataset by employing a direct extraction method. This new method preserves the spectral information at the native instrumental resolution, thereby enabling the application of cross-correlation techniques and providing atmospheric retrievals with enhanced precision and richer information content. With this methodology, we report detections of CO at 4.4σ significance, H_2O at 3.4σ, and OH at 7.8σ, where CO and OH were previously unseen. Building on these unambiguous detections, our subsequent retrieval analysis significantly improves the constraints on atmospheric abundances. Our results demonstrate that the cross-correlation technique effectively extracts molecular signals from medium-resolution JWST data, enhancing detection sensitivity. By revisiting JWST archival data with cross-correlation and retrieval analysis, we can achieve a more comprehensive survey of planetary atmospheric chemistry, thereby placing precise constraints on key parameters such as planetary metallicity and C/O ratio.

This study presents a comprehensive end-to-end simulation analysis of the optical imaging performance of the Chinese Space Station Survey Telescope (CSST) under in-orbit conditions. An integrated system model incorporating five static and two dynamic error sub-models was established. Wave front errors were calculated for each sub-model and compared to the integrated system error to quantify the individual contributions to image degradation. At the detector level, wave front error, point-spread function (PSF), and ellipticity were evaluated across the full field of view (FOV). The average radius of 80% encircled energy (REE80) of the PSF under full-error conditions was determined for 25 field points, yielding a value of 0 . ″ 114. Furthermore, the calculations indicate a correlation between the wave front distribution and the ellipticity distribution within the optical system. By optimizing the wave front distribution, it is possible to adjust the ellipticity distribution of the PSF across the full FOV. The end-to-end simulation approach adopted in this paper provides a theoretical foundation for improving the image quality in large-aperture, off-axis space telescopes.

Transmission spectroscopy has become a primary tool for probing exoplanetary atmospheres, enabling constraints on their chemical compositions and providing limited information on their thermal properties. We assess the potential of the upcoming Chinese Space Station Telescope (CSST) for exoplanet atmospheric characterization through transmission spectroscopy. Theoretical spectra of hot gas planets are generated and used to simulate slitless spectroscopic observations with the CSST across the ultraviolet-to-near-infrared range. Atmospheric retrievals performed on the simulated data are compared with the input models to assess the robustness and accuracy of parameter determinations. We find that multi-band observations across three wavelength channels, each with two transits can place meaningful constraints on key atmospheric parameters. For multi-band observations that account for correlated (red) noise, future CSST observations are expected to achieve constraints that are comparable to, or in some cases slightly weaker than, those of the Hubble Space Telescope (HST), depending on the noise level and observing strategy. We conclude that CSST will provide unique and complementary constraints on the chemical compositions and physical properties of exoplanetary atmospheres, particularly for atomic species, metal-bearing molecules, and scattering processes accessible in the UV and optical, thereby complementing JWST's infrared sensitivity to molecular species.

The Chinese Space Station Survey Telescope (CSST) is a flagship space-based observatory. Its main survey camera is designed to conduct high spatial resolution near-ultraviolet to near-infrared imaging and low-resolution spectroscopic surveys. To maximize the scientific output of CSST, we have developed a comprehensive, high-fidelity simulation pipeline for reproducing both imaging and spectroscopic observations. This paper presents an overview of the simulation framework, detailing its implementation and components. Built upon the GalSim package and incorporating the latest CSST instrumental specifications, our pipeline generates pixel-level mock observations that closely replicate the expected instrumental and observational conditions. The simulation suite integrates realistic astrophysical object catalogs, instrumental effects, point-spread function modeling, and observational noises to produce accurate synthetic data. We describe the key processing stages of the simulation, from constructing the input object catalogs to modeling the telescope optics and detector responses. Furthermore, we introduce the most recent release of simulated datasets, which provide a crucial testbed for data processing pipeline developments, calibration strategies, and scientific analyses, ensuring that CSST will meet its stringent requirements. Our pipeline serves as a vital tool for optimizing CSST main survey strategies and ensuring robust cosmological measurements.

Halo star clusters serve as vital tracers for the formation and evolution of the Andromeda galaxy. In this work, we present physical parameters for 29 M31 halo star clusters, derived from a combination of spectroscopic and photometric data. Low-resolution spectra were acquired using the Beijing Faint Object Spectrograph and Camera spectrograph on the National Astronomical Observatories, Chinese Academy of Sciences Xinglong 2.16 m telescope. For the photometric analysis, we utilized u _SC and v _SAGE bands from the SAGE survey, complemented by archival data from Galaxy Evolution Explorer (near-ultraviolet and far-ultraviolet), PAN-STARRS ( grizy ), and the Two Micron All Sky Survey ( JHK ). Ages and metallicities were determined via ULySS (Vazdekis et al. and pegase-hr) simple stellar population model and the G. Bruzual & S. Charlot stellar population synthesis models. The derived parameters show good agreement with literature values. Notably, for three of these clusters, this study represents the first combined photometric and spectroscopic analysis.

Slow-rotating evolved stars frequently exhibit radial velocity (RV) variations on annual timescales, complicated by instrumental systematics and aliasing in the one-year regime. Here, we investigate the origin of the near-yearly periodicity in 2 Dra, a star located in the red-clump region, assessing possible causes between stellar activity, instrumental profile (IP) effects, sampling alias, and planetary companions. We applied two independent approaches: (1) constraining diagnostic signals and performing a correlation analysis (r) between period-confined signals and (2) evaluating phase stability by partitioning Keplerian fits. These methods enabled us to examine the physical connections and phase coherence among stellar activity indicators, RV measurements, and IP diagnostics. Our analysis suggests a stellar rotation period of similar or equal to 270-320 d for 2 Dra. The 340 d RV signal does not appear to originate from stellar activity in this chromospherically quiet star (|r|less than or similar to 0.33), nor from instrumental systematics near the annual period (|r|less than or similar to 0.1). This conclusion is supported by contrasting phase behavior: the RV and stellar activity phases remain stable, whereas the IP phases do not. We therefore propose that the 340 d variation likely arises from either a small-amplitude intrinsic variability or a tentative gas giant companion with potential weak activity-induced modulation. The case of 2 Dra provides a framework for distinguishing the origins of similar to 1 yr RV variations in other evolved stars.

The Chinese Space Station Survey Telescope (CSST) is an upcoming Stage-IV sky survey telescope, distinguished by its large field of view (FoV), high image quality, and multi-band observation capabilities. It can simultaneously conduct precise measurements of the Universe by performing multi-color photometric imaging and slitless spectroscopic surveys. The CSST is equipped with five scientific instruments, i.e., Multi-band Imaging and Slitless Spectroscopy Survey Camera (SC), Multi-Channel Imager (MCI), Integral Field Spectrograph (IFS), Cool Planet Imaging Coronagraph (CPI-C), and THz Spectrometer (TS). Using these instruments, CSST is expected to make significant contributions and discoveries across various astronomical fields, including cosmology, galaxies and active galactic nuclei (AGN), the Milky Way and nearby galaxies, stars, exoplanets, Solar System objects, astrometry, and transients and variable sources. This review aims to provide a comprehensive overview of the CSST instruments, observational capabilities, data products, and scientific potential.

Observations of exoplanetary atmospheres provide critical insights into their chemical composition, formation, and evolution history. Ultra-hot Jupiters serve as excellent targets for atmospheric characterization; studies of these planets may yield key understanding of gas giants' formation and evolution history. We present a thermal emission study of WASP-33 b's dayside atmosphere, based on two secondary eclipse observations with CFHT/WIRCam in two specific narrow band filters, namely the CO and CH4(on) filters, and archival data with HST/WFC3 and Spitzer. Stellar pulsations of the host star induce some quasi-periodic photometric variations, particularly in the CH4(on) band, which are modeled and corrected in the high-precision differential light curves. An eclipse depth of 1565.2(-237.5)(+228.6) ppm and 914.3(-57.0)(+56.1) ppm is determined for the CO and CH4(on) bands, respectively. Combined with HST/WFC3 and Spitzer data, our joint retrieval of WASP-33 b's dayside atmosphere reveals a high metallicity ([Fe/H] = 1.52(-0.52)(+0.35)), high C/O ratio (C/O = 0.78(-0.04)(+0.03)), and a thermal inversion layer, suggesting a formation history involving metal-rich gas accretion. We confirm the presence of the molecules H2O, H+ and CO, and report a tentative detection of TiO in the dayside atmosphere of WASP-33 b. Future higher precision observations with JWST may provide better understanding of constraints on the chemical abundances of oxygen and refractory element abundances to better constrain WASP-33 b's formation and evolutionary pathway.

The Multi-Channel Imager (MCI) is a powerful near-ultraviolet (NUV) and visible imager onboard the Chinese Space Station Survey Telescope (CSST). The MCI provides three imaging channels, which are the NUV channel, the Blue channel and the Red channel, with the wavelength ranges of 255-430 nm, 430-700 nm, and 700-1000 nm, respectively. MCI's three channels can target the same field simultaneously, which is unique compared to other imagers onboard the Hubble Space Telescope (HST) or the James Webb Space Telescope (JWST). Each channel employs a CCD focal plane of 9216 & times; 9232 pixels and similar to 7.' 5 & times;7.' 5 field of view (FOV), which are greater than or similar to 4 times the FOVs of HST imagers. The MCI's three channels feature unprecedented sensitivities and FOVs, complementing the NUV and visible capabilities of the CSST for high-precision photometry and weak-signal detection, which would help build a new standard-star system and the deepest UV-Optical exposures for CSST. Rich filter sets of MCI would help explore other areas of science such as local emission line mapping, searching for high-z Ly alpha emitters, etc. Here we present key design features, results of current ground tests, and suggest observing strategies for the MCI.

The James Webb Space Telescope (JWST) has revolutionized the characterization of exoplanetary atmospheres, offering unprecedented sensitivity to probe their chemical and physical properties. Recently, a growing trend has emerged to obtain atmospheric information directly from pixel-level planetary spectra. In this work, we reanalyzed the WASP-18 b NIRISS/SOSS data set by employing a direct-extraction method. This new method preserves the spectral information at the native instrumental resolution, thereby enabling the application of cross-correlation techniques and providing atmospheric retrievals with enhanced precision and richer information content. With this methodology, we report detections of CO at 4.4 sigma significance, H2O at 3.4 sigma, and OH at 7.8 sigma, where CO and OH were previously unseen. Building on these unambiguous detections, our subsequent retrieval analysis significantly improves the constraints on atmospheric abundances. Our results demonstrate that the cross-correlation technique effectively extracts molecular signals from medium-resolution JWST data, enhancing detection sensitivity. By revisiting JWST archival data with a cross-correlation and retrieval analysis, we can achieve a more comprehensive survey of planetary atmospheric chemistry, thereby placing precise constraints on key parameters such as planetary metallicity and the C/O ratio.

Hot Jupiters (HJs), especially the ultrahot Jupiters (UHJs), are ideal targets for robust atmospheric characterization, thanks to their high equilibrium temperatures and large atmospheric scale heights, which result from their proximity to their host stars and intense stellar irradiation. Here, we present atmospheric studies of five planets, namely WASP-50 b, WASP-117 b, WASP-156 b, WASP-167 b, and WASP-173 Ab. These five planets include two UHJs, two classic HJs, and one hot Neptune, with four of them just on the upper and middle borders of the Neptune desert, providing an interesting sample to investigate the connection between planetary atmospheric composition and bulk properties. We have not detected any significant absorption signals exceeding 3 sigma in the three less-inflated, relatively high-density HJs (WASP-50 b, WASP-156 b, and WASP-173A b). We marginally detect H alpha and Li i with 3.2 sigma and 3.1 sigma in WASP-117 b, respectively. In WASP-167 b, we report tentative detection of H alpha and Fe i at 4.6 sigma and similar to 3.4 sigma, respectively. In addition, Fe i is significantly detected with a maximum signal-to-noise ratio of 7.3 sigma using the cross-correlation technique, which exhibits a blueshifted signal. For WASP-167 b, we perform an atmospheric retrieval and yield the abundances of Fe, Mg, Ca, Ti, and V, and equilibrium temperature of 2479-174+193 K. Comparing WASP-173A b and WASP-167 b, both are UHJ but with quite different extents of atmospheric signals, we propose that there may be a transition in Teq between 1900 and 2300 K.

We present a revisiting study of the brown dwarf pair orbiting the naked-eye (V=3.3) K-giant ν Ophiuchi, located only 44 pc from our Solar system. By jointly analysing archival radial-velocity measurements together with astrometric data from Hipparcos and the Gaia second and third data releases, we determine the three-dimensional architecture of the system and robustly constrain the masses of both companions. We find brown dwarf masses of m_b = 24.2^+6.4_-2.8 M_J and m_c = 26.8^+4.3_-2.9 M_J. The mathematical constraint, derived from the posterior distribution of the mutual inclination based on MCMC samples, yields a mutual inclination of ψ_bc=46^+27_-24 ^∘, while direct calculations based on the maximum a posteriori and posterior median orbital parameters yield values of ∼10^∘ and ∼20^∘, respectively. Resonance analysis indicates that the two companions can still be trapped in a 6:1 mean-motion resonance in the maximum a posteriori configuration. To place an upper limit for the mutual inclination, dynamical stability analysis over a 1 Myr timescale further constrains it to be no larger than ∼15^∘. Systems hosting brown dwarf pairs are rare, yet they provide important constraints on theories of planetary formation and dynamical evolution. Current detections suggest that brown dwarf pairs preferentially reside at large separations from their host stars and are more common in less mature systems. This supports a star-like formation pathway via gravitational instability in disk.

This paper presents pre-launch testing and calibration results for the SVOM/VT (Space-based Variable Objects Monitor, Visible Telescope) Flight Model (FM), validating its performance under simulated space conditions through thermal vacuum cycling, energy concentration analysis, stray light suppression, and CCD/electronics calibrations (gain, noise, quantum efficiency). The results confirm full compliance with design requirements: stray light suppression achieves point-source transmittance <10^-7 at 30^∘ off-axis, thermal control maintains stable CCD temperatures (-75^∘C for the red channel, -65^∘C for the blue channel), and detection sensitivity meets the limiting magnitude of 22.50 (SNR > 3 with 300 seconds exposure). Early in-orbit tests further validate performance, yielding limiting magnitudes of 22.70 (V-band, red) and 22.78 (blue), consistent with pre-launch specifications.

Helium plasma experiments conducted on different tokamaks all demonstrate that the energy confinement are lower than those of deuterium plasmas under similar operation conditions. However, the origin of the difference in confinement between helium and hydrogen isotopes remains unclear. To understand the influence of helium concentration, which leads to the variation of ion mass and charge number, on energy confinement, new helium experiments were conducted in the EAST tokamak with dominant electron heating and a tungsten divertor in 2025. A notable dependence on both ion mass and charge number is observed in the effective diffusion coefficient, consistent with the trend predicted by the gyro-Bohm scaling ${{\chi }}{}_{{\text{gB}}}^{\text{ }}{\text{ }} \propto {{\rho }}{}_{\text{i}}^{\text{ }}{\text{ }}$ . The higher energy confinement time is observed with a lower ion mass. Conversely, when both the ion mass and charge number are increased, the energy confinement time is found to be similar. Power balance and transport analyses indicate that the ion-electron collision, significantly influenced by the variation of ion mass and charge number, appears to play a dominant role in regulating ion-scale turbulence in helium H-mode discharges. Furthermore, linear electromagnetic gyrokinetic simulation reveals that the linear growth rates of electron temperature gradient (ETG) modes might be reduced by the enhancement of ion-electron energy exchange in L-mode discharges. Consequently, it is crucial to take into account the role of electron-ion collision/energy exchange to understand the influence of ion mass and chargenumber on energy confinement. These results contribute to a better understanding of the transport characteristics in multi-ion-component plasma.

We present the first public data release of the DDO51 band from the Stellar Abundances and Galactic Evolution Survey (SAGES), based on Nanshan One-meter Wide-field Telescope observations obtained between 2023 September and 2024 January. This release initiates the DDO51-band component of the survey, covering similar to 2500 deg2 of the northern sky and including more than 10 million sources. The DDO51 filter is centered near the Mg i b triplet and the adjacent MgH feature, offering sensitivity to stellar surface gravity. The data reduction pipeline incorporates an improved astrometric solution anchored to Gaia DR3 and a photometric calibration strategy tied to synthetic photometry from Gaia XP spectra. These procedures yield a point-source depth of similar to 18.9 mag at a signal-to-noise ratio similar to 10 and an internal photometric precision approximate to 6-7 mmag at the bright end. A preliminary color-color analysis using Gaia broadband photometry confirms the expected sensitivity of the DDO51 band to stellar surface gravity, demonstrating a clear photometric separation between dwarf and giant sequences for late-type stars. This dataset, when combined with existing SAGES photometry in other bands, provides a crucial tool for disentangling the substructures of the Milky Way. All data products from this release are available upon publication.