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Ju-Yong Zhang

Publications and source records attributed to Ju-Yong Zhang.

3 recordsLinked to original sources

The Stellar "Snake"-V: the census within 3 kpc in the Solar Neighborhood

We present a Gaia DR3 source-level census of \emph{Stellar Snake} complexes within 3\,kpc of the Sun. We define a Stellar Snake as a mutually coherent association of two or more stellar overdensities, characterised by consistent positions, kinematics, orbital invariants, ages, and chemical properties, rather than as a single gravitationally bound object. Moving beyond catalogue-driven searches seeded by known open clusters, our framework operates directly on individual Gaia sources to recover extended, low-density substructures and interconnecting stellar bridges. The multi-stage pipeline extracts statistically significant, non-overlapping base nodes, infers homogeneous parameters using a PointNet point-cloud regressor, and links these nodes into large-scale macro-structures across a 9D space spanning positions, tangential velocities, radial velocity, age \(\log t\), and orbital integrals \((E,L_Z)\). After FoF-topology cross-validation and boundary resolution, the final catalogue contains 1,256 Stellar Snake candidates comprising 802,489 unique member-star entries in 5,491 final base nodes selected from a 9,909-node input pool. Derived parameters are validated against external open-cluster catalogues and spectroscopic benchmarks. To quantify structural coherence, we introduce a graph-relation Snake Reliability Index (SRI), coupled with a peripheral-branch diagnostic and Gold/Silver/Bronze quality flags. At the population level, the census shows a broad age--metallicity pattern, a declining upper envelope of member-star entries toward older ages, and a projected association between young Snake nodes, nearby spiral-arm loci, and the Radcliffe Wave. This homogeneous inventory provides an observational foundation for probing the formation, coherence, and dynamical evolution of hierarchical stellar complexes in the Milky Way.

astro-ph.GA

Design and Implementation of a Scalable Correlator Based on ROACH2+GPU Cluster for Tianlai 96-Dual-Polarization Antenna Array

The digital correlator is one of the most crucial data processing components of a radio telescope array. With the scale of radio interferometeric array growing, many efforts have been devoted to developing a cost-effective and scalable correlator in the field of radio astronomy. In this paper, a 192-input digital correlator with six CASPER ROACH2 boards and seven GPU servers has been deployed as the digital signal processing system for Tianlai cylinder pathfinder located in Hongliuxia observatory. The correlator consists of 192 input signals (96 dual-polarization), 125-MHz bandwidth, and full-Stokes output. The correlator inherits the advantages of the CASPER system, for example, low cost, high performance, modular scalability, and a heterogeneous computing architecture. With a rapidly deployable ROACH2 digital sampling system, a commercially expandable 10 Gigabit switching network system, and a flexible upgradable GPU computing system, the correlator forms a low-cost and easily-upgradable system, poised to support scalable large-scale interferometeric array in the future.

astro-ph.IM

The Stellar "Snake" -- II: The Mass Function

We present a comprehensive investigation on the mass function (MF) of a snake-like stellar structure in the solar neighbourhood, building on our previous discovery. To ensure the reliability of the data, we reselect the member stars of the Stellar ``Snake'' in the latest {\it Gaia} Data Release 3 using the same approach as the initial series of articles. We also precisely measure the physical parameters of the clusters within the Stellar Snake. In light of the high completeness of the member stars in the cluster regions, we develop a simulated model color-magnitude diagram-based inference method to derive the mass function, binary fraction, and mass-ratio distribution of the clusters in the Stellar Snake. Notably, despite their similar ages and metallicity, we discover systematic variations in the MFs along the elongation direction of the Snake in the mass range of 0.5 to 2.0 M$_\odot$. The ``head'' of the Snake conforms to a canonical initial mass function with a power-law slope of $α\sim-2.3$. Extending towards the ``tail,'' the MF becomes more top-light, indicating a deficiency of massive stars within these clusters. This result provides evidence for the delayed formation of massive stars in the clusters. Such clues give support to the hypothesis that the Stellar Snake constitutes as a hierarchically primordial structure.

astro-ph.GA