arXiv subjects

Biwei Jiang

Publications and source records attributed to Biwei Jiang.

At least 19 recordsLinked to original sources

arXiv2026

Estimation of Dust Mass from Infrared Emission and Extinction of Supernova Remnants: G93.7-0.2, G109.1-1.0, G156.2+5.7, and G166.0+4.3

Supernova remnants (SNRs) are major sites for both the production and destruction of interstellar dust, and quantifying their dust budget is essential for understanding the life cycle of cosmic dust. In this work, the dust masses of four Galactic SNRs (G93.7$-$0.2, G109.1$-$1.0, G156.2+5.7, and G166.0+4.3) are estimated using two complementary methods: the three-dimensional (3D) interstellar extinction map and infrared (IR) spectral energy distribution (SED) fitting based on photometry from WISE, IRAS, AKARI, and Planck. The extinction masses, derived from the differential extinction within each SNR's distance interval, are 108.3, 82.0, 48.8, and 119.2 $M_\odot$, respectively. A two-component (``warm + cold") modified blackbody fitting yields warm dust temperatures of 43--74\,K and cold dust temperatures of 13--16\,K, with the cold dust component dominating the total IR-emission mass ($\sim$90--400 $M_\odot$). The extinction masses and IR emission masses show systematic differences, likely caused by sightline contamination from unrelated foreground/background material and uncertainties in dust temperatures and opacities.

astro-ph.GA↗

arXiv2026

JWST Reveals a Galaxy-Wide Association of Red Supergiants with OB Stars in NGC 5584

The spatial relationship between young and evolved massive-star tracers offers a means of probing recent star formation across galactic disks. We combine JWST/NIRCam, $Swift$/UVOT UVW2, and GALEX FUV/NUV images to investigate the spatial association between red-supergiant (RSG) candidates and UV-selected star-forming complexes (SFCs) in the spiral galaxy NGC 5584. We identify 5,310 RSG candidates using colour--magnitude criteria and define 106 UV-selected SFCs from the UVOT/UVW2 morphology, with their FUV and NUV luminosities measured independently using the GALEX images. We find that 82% of the UV-selected SFCs overlap significant RSG overdensities, indicating a galaxy-wide statistical association between UV-bright SFCs and the evolved massive-star population. Among the 93 SFCs with reliable JWST coverage, the UV-$\beta$-corrected FUV and NUV luminosities correlate tightly with the JWST/NIRCam luminosities, with Pearson correlation coefficients of $r=0.962$--$0.971$. MIST isochrone comparisons for 43 RSG-rich SFCs indicate a characteristic age of $\log(\mathrm{age/yr})\simeq 7.16$. These results show that RSG overdensities and UV-selected SFCs trace related but distinct phases of recent massive-star formation. Their spatial correspondence is statistical rather than one-to-one and likely reflects differences in stellar age, dust extinction, spatial resolution, aperture coverage, and local star-formation history.

astro-ph.SR↗

arXiv2026

Divergent Evolution of Radial Metallicity Gradients in the Thin and Thick Disks of the Milky Way

Using 200,388 red clump stars from LAMOST and APOGEE, we investigate the radial metallicity gradients of the Galactic disk as a function of vertical height and stellar age. The thin disk displays a pronounced negative radial metallicity gradient near the Galactic mid-plane that progressively flattens with increasing $|Z|$, following $\Delta \mathrm{[Fe/H]}/\Delta R$ = $-$0.0784 $+$ 0.0776 (1 $-$ exp ($-$ $|Z|$/1.42)). The thin disk also exhibits a clear age dependence in radial metallicity gradients, evolving smoothly from a strong gradient regime for young stars to a weak gradient regime for old stars, following $\Delta \mathrm{[Fe/H]}/\Delta R$ = $-$0.0438 $+$ 0.0233 tanh (($\tau$ $-$ 11.29)/4.21). The thick disk shows weakly positive radial metallicity gradients that remain statistically invariant with respect to both vertical height and stellar age, following respectively, $\Delta \mathrm{[Fe/H]}/\Delta R$ = 0.0038 $+$ 0.0009 $|Z|$ and $\Delta \mathrm{[Fe/H]}/\Delta R$ = 0.0146 $-$ 0.0007 $\tau$. These results indicate that the thin disk retains radial metallicity gradients shaped by relatively ordered inside-out growth and long-term secular evolution processes. The thick disk exhibits spatially and temporally homogeneous radial metallicity gradients, which are consistent with a formation environment characterized by mergers of gas-rich systems and/or the turbulent ISM.

astro-ph.GA↗

arXiv2026

Distance Determination of Southern Galactic Plane Supernova Remnants with the Mopra CO Survey and DECaPS 3D Dust Map

Accurate distance measurements to supernova remnants (SNRs) are crucial for understanding their physical properties, evolutionary processes, and role in the Galactic interstellar medium (ISM) cycle. In this study, we apply for the first time to the southern Galactic plane a distance determination method that utilizes CO emission data from the Mopra survey to identify molecular clouds (MCs) interacting with SNRs. By combining this with extinction-distance profiles from the DECaPS three-dimensional (3D) extinction map, we directly measure the distances to the associated MCs, thereby obtaining precise distances to the remnants. To overcome the extinction-missing bias in extremely dense regions where the 3D map suffers from a deficit of background stars, we supplement our analysis with two-dimensional (2D) extinction maps as cross-validation. Applying this method, we have derived precise distances for nine SNRs: G290.1-0.8 (7.32+0.60/-0.47 kpc), G292.2-0.5 (10.85+0.43/-0.68 kpc), G296.1-0.5 (4.59+0.18/-0.19 kpc), G296.8-0.3 (8.74+0.40/-0.29 kpc), G298.6-0.0 (6.50 +/- 0.21 kpc), G312.4-0.4 (3.60+0.19/-0.23 kpc), G332.4-0.4 (2.66+0.23/-0.15 kpc), G335.2+0.1 (2.76+0.37/-0.31 kpc), and G353.6-0.7 (1.81+0.18/-0.14 kpc). Additionally, we established a robust lower distance limit of 1.34 kpc for G351.7+0.8.

astro-ph.GA↗

arXiv2026

The First Glimpse of Water Ice Absorption Map in the Milky Way

Interstellar ice plays a key role in the thermal evolution of the interstellar medium and in astrochemical pathways, yet its large-scale distribution remains poorly constrained. We use ALLWISE and 2MASS photometry to estimate water ice absorption in the $\Wi$/WISE band by correcting the observed colors for reddening and intrinsic stellar colors. This allows us to construct a first Milky Way water ice map. By varying input parameters, we test the stability of the method and identify the extinction law as the dominant source of uncertainty. Using synthetic photometry, we also quantify how different physical and observational parameters influence the $\Wi$ band water ice absorption. The strong correlation between the measurement from photometric method and spectroscopic water ice abundance confirms that the $\Wi$ band signature originates from the 3 $\mu$m ice feature. We present the relationship between ice absorption in $\Wi$ band and water ice optical depth from theory and observations. Finally, we provide a preliminary Milky Way-scale map of water ice distribution.

astro-ph.GA↗

arXiv2026

Evidence of triggered star formation in the Pillars of Creation from JWST observations

Stars form in molecular clouds under the influence of their local environments, yet the role of massive stellar feedback in either triggering or suppressing star formation remains a fundamental question in astrophysics. The Pillars of Creation in the Eagle Nebula, sculpted by ionizing radiation and stellar winds from massive stars in NGC 6611, offer a natural laboratory for investigating this question. Here we present high-resolution observations of the Pillars of Creation using the JWST Near Infrared Camera and Mid-Infrared Instrument, revealing 253 young stellar object (YSO) candidates. These YSO candidates show spatial correlations with the edges of feedback-driven structures, with overdensities along the boundaries. A weak trend of decreasing stellar age with increasing distance from the ionizing source was tentatively observed. There also appears to be an enhancement in the star formation rate within the past 1 Myr in this region. Such age and spatial associations suggest that while the bulk of the YSOs may have formed contemporaneously with the central cluster, a subset could be associated with triggered star formation. The JWST image of intricate structures, including a spiral-like disk and bi-reflection nebulae at the tips of Pillar I and Pillar II, further highlights the complexity of star formation processes.

astro-ph.SR↗

arXiv2026

Rotationally modulated highly circularly polarised radio pulses from the rapidly rotating M dwarf ASKAP J181335-604720

We report the detection of strong, highly circularly polarised, and rotationally modulated radio pulses from the early-mid M dwarf ASKAP J181335-604720, based on strictly simultaneous radio and optical observations with the Australian Square Kilometre Array Pathfinder (ASKAP) and the Transiting Exoplanet Survey Satellite (TESS). The ASKAP data reveal recurrent broadband radio pulses across 800-1088 MHz, with peak circular polarisation fractions approaching 100%. A dominant period of P = 5.607 +- 0.003 h is derived from the TESS light curve using a Lomb-Scargle analysis, which we interpret as the stellar rotation period. When phase-folded on this period, the radio emission is confined to narrow phase intervals and recurs at fixed rotational phases, consisting of a dominant pulse and a weaker secondary component. No contemporaneous optical flares are detected at the epochs of the radio pulses in the simultaneous TESS data. Even under conservative assumptions, the inferred brightness temperature exceeds Tb > 1.8 * 10^12 K, ruling out incoherent emission mechanisms. Combining the observed characteristics, we interpret the emission as coherent electron cyclotron maser (ECM) radiation arising from the stellar magnetosphere, with the observed frequencies implying local magnetic field strengths of at least several hundred Gauss in the radio-emitting region. This work provides a clean, well-constrained, and strictly simultaneous radio-optical case, demonstrating that coordinated radio and optical observations offer a powerful means of distinguishing magnetospheric coherent radio emission from flare-associated coronal activity in M dwarfs.

astro-ph.SR↗

arXiv2026

The Extinction Distance of Supernova Remnants in Combination with the CO Line Measurements

Accurate distance measurements to supernova remnants (SNRs) are crucial for understanding their physical properties and evolution. We present a novel method that combines CO line observations with three-dimensional (3D) extinction maps to determine distances to SNRs (G93.7$-$0.2, G109.1$-$1.0, G156.2+5.7, and G166.0+4.3) through their associated molecular clouds. For each SNR, candidate CO velocity components corresponding to interacting molecular clouds are identified based on previous observational evidence with refinements: [$-$19, $-$3] km s$^{-1}$ for G93.7$-$0.2, [$-$51, $-$46] km s$^{-1}$ for G109.1$-$1.0, [$-$10, 0] km s$^{-1}$ for G156.2+5.7, and [$-$27, $-$15] km s$^{-1}$ for G166.0+4.3. By examining extinction-distance profiles along the sightlines and identifying extinction jumps that spatially coincide with CO emission features, we derive distances of 1.82$\pm$0.13 kpc for G93.7$-$0.2, 3.05$\pm$0.15 kpc for G109.1$-$1.0, 0.60$\pm$0.15 kpc for G156.2+5.7, and 3.44$\pm$0.23 kpc for G166.0+4.3. Our extinction-based distances are largely consistent with previous estimates while with better accuracy and robustness.

astro-ph.GA↗

arXiv2026

The extinction distances for over a thousand planetary nebulae with Gaia measurements

Although Gaia has identified the central stars of planetary nebulae (CSPNe) for about 70% of known Galactic planetary nebulae (PNe), reliable distance estimates remain incomplete, with fewer than one quarter having accurate parallaxes. Meanwhile, classical extinction-distance samples include only about 70 objects, corresponding to 1.8% of the Galactic PN population. We aim to construct a large and homogeneous catalogue of PN distances by refining extinction-distance measurements with Gaia DR3, providing an independent complement to CSPN parallax-based distances. We develop a Gaia-based extinction-distance method by combining an improved blue-edge approach with an extinction-jump model. PN distances are derived from stellar extinction jumps in line-of-sight extinction-distance profiles and are further constrained by comparisons with published distances, the spatial distribution of stars relative to the PN centre, and the PN radius-distance relation. We obtain distances for 1,066 PNe with a median relative uncertainty of 13%, with about 87% of the sample having uncertainties below 20%. The catalogue includes 765 PNe whose CSPN parallaxes have uncertainties greater than 20% and 128 PNe without CSPN parallaxes. This method complements CSPN parallax-based approaches and extends the traditional extinction-based method to higher Galactic latitudes. For PNe with discrepant literature distances, it helps identify the more reliable estimates and assess CSPN identifications. We find a likely misidentification of the reported CSPN for Fr2-36 and analyse 33 PNe with two CSPN candidates, suggesting improved identifications for 15 objects. This catalogue represents the largest homogeneous set of extinction-based PN distances to date and provides a robust benchmark for studies of Galactic structure, PN populations, and interstellar extinction.

astro-ph.GA↗

arXiv2026

Identifying Red Supergiants in the Local Group Using JWST Photometry. I. NGC 6822, Sextans A, NGC 300, WLM, and IC 1613

Red supergiants (RSGs) are crucial for studying the properties and evolution of massive stars. It is representative to conduct a census of RSGs across the Local Group, which spans a broad metallicity range. However, identifying RSGs in distant and metal-poor galaxies remains challenging mainly due to contamination of foreground dwarfs and observational limitations. In this work, we perform PSF photometry on publicly released JWST/NIRCam images of five Local Group galaxies: NGC 6822, Sextans~A, NGC 300, WLM, and IC 1613 using the DOLPHOT NIRCam module. We find an optimal color-color diagram (CCD) for metal-poor environments, that is F115W $-$ F200W versus F356W $-$ F444W, which clearly separates RSGs from foreground dwarfs. By using the CCD, we identify 208, 135, and 22 RSG candidates in NGC 6822, Sextans A, and NGC 300, respectively, free from contamination by foreground dwarfs and oxygen-rich asymptotic giant branch stars (O-AGBs). In addition, 40 and 14 RSG candidates are directly selected on the CMD in WLM and IC 1613, respectively. Compared with previous works, the number of RSG candidates within the same luminosity range and sky region increases significantly, demonstrating the advantages of JWST in constructing a more complete RSG sample in the Local Group thanks to its high spatial resolution and photometric quality. In addition, catalogs of O-AGBs and carbon-rich AGBs (C-AGBs) are provided as by-products.

astro-ph.GA↗

arXiv2026

An Enhanced Sample of Galactic Red Supergiants Reveals Spiral Structures

Red supergiants (RSGs), representing a kind of massive young stellar population, have rarely been used to probe the structure of the Milky Way, mainly due to the long-standing scarcity of Galactic RSG samples. The Gaia BP/RP spectra (hereafter XP), which cover a broad wavelength range, provide a powerful tool for identifying RSGs. In this work, we develop a feedforward neural network classifier that assigns to each XP spectrum a probability of being an RSG, denoted as $\mathrm{P(RSG)}$. We perform ten independent runs with randomly divided training and validation sets, and apply each run to all XP spectra of stars with $G < 12$ mag. By selecting sources with $\mathrm{P(RSG)} \geq 0.9$, ten high-confidence candidate samples are obtained. A star is considered a ture Galactic RSG only if it appears in at least eight of these samples, yielding a final catalog of 2,436 objects. These RSGs show a clear spatial correlation with OB stars and trace the Galactic spiral arms well, confirming the reliability of our classification, and highlighting their potential to serve as powerful tracers of the Milky Way's structure.

astro-ph.GA↗

arXiv2026

Exploring the formation mechanisms of tidal structures in globular clusters of extragalactic origin

Tidal structures around globular clusters provide valuable insights into cluster evolution and the hierarchical assembly of the Milky Way. Using wide-field imaging data from the DESI Legacy Survey combined with a color-magnitude matched-filter technique, we perform a systematic analysis of extra-tidal features in 28 Galactic globular clusters of likely extragalactic origin, representing the largest homogeneous sample examined in this context to date. The clusters display diverse morphologies: 12 exhibit tidal tails, 9 show diffuse envelopes, and 7 reveal no clear extra-tidal features. Notably, we report the first detection of an extended tidal structure around the Sagittarius-associated cluster Terzan 7. To explore the underlying drivers, we compare intrinsic properties, orbital dynamics, and possible accretion associations across morphological groups. From the parameter distributions, complemented by Kolmogorov-Smirnov tests, we find that total mass, escape velocity, concentration, tidal filling factor, pericentric radius, eccentricity and radial angle in action-angle coordinates are all likely group-sensitive parameters. These results suggest that both internal cluster properties and orbital configurations play important roles in shaping extra-tidal morphologies. In addition, the cluster's accretion history shows no clear correlation with the presence of tidal features, indicating that it is not a direct driver of outer structure formation. Overall, the diversity of tidal structures is unlikely to be governed by a single factor, but instead reflects the interplay between internal dynamical evolution and the external Galactic environment. This study provides the most comprehensive constraints so far on the physical processes driving extra-tidal structures in accreted globular clusters.

astro-ph.GA↗

arXiv2025

On Recommending Category: A Cascading Approach

Recommendation plays a key role in e-commerce, enhancing user experience and boosting commercial success. Existing works mainly focus on recommending a set of items, but online e-commerce platforms have recently begun to pay attention to exploring users' potential interests at the category level. Category-level recommendation allows e-commerce platforms to promote users' engagements by expanding their interests to different types of items. In addition, it complements item-level recommendations when the latter becomes extremely challenging for users with little-known information and past interactions. Furthermore, it facilitates item-level recommendations in existing works. The predicted category, which is called intention in those works, aids the exploration of item-level preference. However, such category-level preference prediction has mostly been accomplished through applying item-level models. Some key differences between item-level recommendations and category-level recommendations are ignored in such a simplistic adaptation. In this paper, we propose a cascading category recommender (CCRec) model with a variational autoencoder (VAE) to encode item-level information to perform category-level recommendations. Experiments show the advantages of this model over methods designed for item-level recommendations.

cs.IR↗

arXiv2025

Optimal signals assignment for eBay View Item page

Signals are short textual or visual snippets displayed on the eBay View-Item (VI) page, providing additional, contextual information for users about the viewed item. The aim in displaying the signals is to facilitate intelligent purchase and to incentivise engagement. In this paper, we present two approaches for developing statistical models that optimally populate the VI page with signals. Both approaches were A/B tested, and yielded significant increase in business metrics.

cs.IR↗

arXiv2025

The frequency-independent radio luminosity -- orbital/rotational period relation of RS CVn stars

Radio emissions from RS CVn objects exhibit distinct characteristics at low and high frequencies, widely attributed to differing radiation mechanisms. The disparate processes of high-frequency gyrosynchrotron and low-frequency electron cyclotron maser emissions have traditionally suggested an absence of correlation in their radio luminosities. Our study presents a frequency-independent linear correlation between radio luminosity ($L_R$) and orbital/rotational periods ($P$) in RS CVn binaries. Analyzing the Sydney Radio Star Catalogue (SRSC) data, we derived orbital periods for 42 of 60 RS CVn sources using TESS light curves, revealing a strong positive correlation (PCC = 0.698, $P$ = 3.95e-7) between $\log_{10}L_R$ and $\log_{10}P$. This correlation remains across frequencies from 144-3000 MHz, showing uniform luminosity behavior. By combining light curve analysis with stellar mass-radius-luminosity relationships, we calculated parameters like binary mass, primary/secondary mass, Rossby number, and binary separation for eight RS CVn systems. The results show a notable correlation between radio luminosity and binary mass, primary mass, and separation (PCC = 0.663, 0.663, 0.719), with separation showing the strongest correlation. This suggests the radio emission may largely originate from the binary components' interaction, challenging existing models of RS CVn radio emission mechanisms and offering insights into the individual versus collective origins of these emissions.

astro-ph.SR↗

arXiv2025

The structural and kinematical properties of NGC 5634, a globular cluster associated with the Sagittarius dwarf galaxy?

We investigate the origin of NGC 5634 through a comprehensive analysis of its morphology, kinematics and dynamics. Utilizing data from the DESI Legacy Survey, we refined its fundamental parameters (age t = 12.8 +/- 0.3 Gyr, metallicity [Fe/H] = -1.8 +/- 0.1 dex, distance modulus dm = 17.0 +/- 0.1 mag) and constructed matched-filter template based on the combination of these parameters to search for extra-tidal structures. However, no significant features were detected above a 3 sigma signal-to-noise threshold, which limits our ability to further investigate the association between NGC 5634 and the Sagittarius (Sgr) stream based on morphological evidence. Incorporating GAIA data, we further examine the orbital path of NGC 5634. We found that its orbit only briefly intersects with the Sgr stream and diverges significantly over long-term integrations. This behavior contrasts with that of confirmed Sgr-associated clusters, whose orbits remain closely aligned with the stream throughout their orbital evolution. Additionally, NGC 5634 exhibits a relatively shorter semi-major axis and smaller apocenter and pericenter distances compared to Sgr clusters. These orbital characteristics are more consistent with clusters associated with the Gaia-Sausage-Enceladus (GSE) or the Helmi streams. From a dynamical perspective, in the Lz-E space, NGC 5634 is also distinctly different from Sgr clusters and aligns more closely with the GSE and Helmi regions. Taken together, these findings do not support a strong connection between NGC 5634 and the Sgr dSph, but instead suggest a potential association with another progenitor system, such as GSE or Helmi stream. Nevertheless, further evidence is needed to definitively establish its origin.

astro-ph.GA↗

arXiv2025

The Samples and Binary Fractions of Red Supergiant in M31 and M33 by the HST Observations

The binarity of red supergiants (RSGs) influences their evolution and the fate of supernovae. We investigate the binary fraction of RSGs in the Andromeda Galaxy (M31) and Triangulum Galaxy (M33) using photometry from the Hubble Space Telescope (HST), which offers high spatial resolution to resolve more RSGs. A preliminary step involves identifying a reliable and complete RSG sample using the F110W $-$ F160W versus F160W diagram, yielding 2,612 RSGs from the Panchromatic Hubble Andromeda Treasury (PHAT) survey of M31 3,294 RSGs from the Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER) survey of M33. These samples suggest total RSG populations in M31 and M33 of 6,563 and 7,572, respectively. These estimates significantly exceed previous ones from the ground-based observations, an increase attributed to the superior spatial resolution of the HST. The stellar parameters of these RSGs, including effective temperature ($T_{\mathrm{eff}}$), radius ($R$), and luminosity ($L$), are derived by fitting their spectral energy distribution (SED) across optical and near-infrared bands. Binary candidates are identified by detecting ultraviolet (UV) excesses in their SEDs compared to the single-star RSG model prediction. The binary fraction is determined to be 33.4% $\pm$ 0.9% for M31 and 30.9% $\pm$ 0.8% for M33. For more luminous RSGs with log $L/L_{\odot} > 4.0$, the binary fraction decreases to 31.6% $\pm$ 1.9% in M31 and increases to 34.7% $\pm$ 1.8% in M33, respectively. These results are in good agreement with predictions from the BPASS binary evolution model.

astro-ph.SR↗

arXiv2025

Massive Acquisition of Ultraviolet Color Excess Information from GALEX and UVOT Bands

This study employs stellar parameters from spectroscopic surveys and Zhang et al. based on Gaia XP spectra, along with photometric data from GALEX, UVOT, and Gaia, to obtain extensive ultraviolet color excess information for the relevant bands of GALEX and UVOT. By considering the impact of stellar parameters (\teff, \feh, and \logg) on intrinsic color indices, and utilizing the blue-edge method combined with a random forest algorithm, an empirical relationship between stellar parameters and intrinsic ultraviolet color indices is established. By combining observed color indices, the study derives color excesses for 11,624,802 and 65,531 stars in the GALEX/near-UV and far-UV bands, and 336,633, 137,739, and 253,271 stars in the UVOT/\uvwa, \uvmb, and \uvwb\ bands, constructing corresponding ultraviolet extinction maps. Notably, the color excess data for the GALEX/near-UV band shows a tenfold increase from previous results, with the extinction map covering approximately two-thirds of the sky at a resolution of 0.4$^{\circ}$. The typical uncertainties in the ultraviolet color excesses are 0.21 mag, 0.30 mag, 0.19 mag, 0.24 mag, and 0.21 mag for \enb, \efb, \ewab, \embb, and \ewbb, respectively. By comparing the spatial distributions of \rv\ derived from ultraviolet and Gaia optical band measurements with those obtained from infrared and optical data in previous works, it is evident that the \rv\ distributions based on the ultraviolet data show noticeable differences, with some regions even exhibiting opposite trends. This suggests that a single-parameter \rv\ extinction law may not be sufficient to simultaneously characterize the extinction behavior across infrared, optical, and ultraviolet bands.

astro-ph.GA↗