arXiv subjects

Biwei Jiang

Publications and source records attributed to Biwei Jiang.

At least 37 records · Page 2Linked to original sources

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.

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arXiv2025

Metallicity Distribution in M31 and M33 Based on the Tip-RGB Near-infrared Color

This study investigates the metallicity distribution in M31 and M33 by using the near-infrared color index $J-K$ of tip-red-giant-branch (TRGB) of the member stars from \cite{2021ApJ...907...18R} after removing the foreground dwarf stars by the near-infrared $J-H/H-K$ diagram as well as the Gaia astrometric measurements. We employ the Voronoi binning technique to divide the galaxy into sub-regions, the PN method to determine the TRGB position in the $J-K$/$K$ diagram, and the bootstrap method to estimate the uncertainties. The TRGB positions are calculated to be $J-K = 1.195 \pm 0.002$ and $1.100 \pm 0.003$, and $K = 17.615 \pm 0.007$ and $18.185 \pm 0.053$ for M31 and M33 respectively as an entity, consistent with previous results. The $J-K$ gradient of M31 is found to be $-$0.0055 kpc$^{-1}$ at $R_{\rm GC}=(0, 24)$ kpc and $-$0.0002 kpc$^{-1}$ at $R_{\rm GC}=(24, 150)$ kpc. Notably, two dust rings are evident at 11.5 kpc and 14.5 kpc, in agreement with previous studies. The $J-K$ of M33 is analyzed in four directions and generally shows a trend of gradually decreasing from the inside to the outside, however, it shows an increasing trend of 0.022 kpc$^{-1}$ in the inner 0$-$2 kpc in the west. Through the color$-$metallicity relation of TRGB, the metallicity gradient of M31 turns to be $-0.040 \pm 0.0012$ dex kpc$^{-1}$ with $R_{\rm GC}<30$ kpc and $-0.001 \pm 0.0002$ dex kpc$^{-1}$ with $R_{\rm GC}>30$ kpc, and for M33, $-$0.269 $\pm$ 0.0206 dex kpc$^{-1}$ with $R_{\rm GC}<9$ kpc.

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arXiv2025

The Binary Fraction of Red Supergiants in the Magellanic Clouds

Red supergiants (RSGs), as the descendants of OB-type stars and the progenitors of supernovae, provide crucial insights into the evolution of massive stars, particularly in binary systems. Previous studies show that the binary fraction of RSGs ($\approx$ 15% - 40%) is significantly lower than that of their predecessors ($\approx$ 50% - 70%). In this work, we investigate the binary fraction of RSGs with the recently selected largest samples of 4695 and 2097 RSGs in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), respectively. The binary system with a hot companion (O-, B- and A-type star) is identified by detecting the ultraviolet (UV) excess in the observed spectral energy distribution (SED) ranging from ultraviolet to mid-infrared after subtracting the model SED of RSG since RSGs are very weak in the UV band. It is found that the lower limit of binarity is 30.2% $\pm$ 0.7% and 32.2% $\pm$ 1% in the LMC and SMC, respectively. If the sample is limited to luminous RSGs with log $L/L_{\odot} > 4.0$, the binary fraction becomes 26.6% $\pm$ 1.1% and 26.4% $\pm$ 1.7% in the LMC and SMC, respectively. The derived binary fraction is valid in the range of $\sim$ 2.3 < $\log P / [\text{d}]$ < $\sim$ 8. Our study suggests that roughly one-third of massive stars host a third companion within $\sim$ 30,000 AU. In addition, 15 RSGs are also identified as binary via HST/STIS spectra, and a handful of the binaries identified by the SED fitting are confirmed by their light curve and radial velocity dispersion. The stellar parameters of the companions, i.e. $T_{\mathrm{eff}}$, $R$, $L$ and log $g$, are calculated by model fitting.

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arXiv2025

New Red Supergiant Stars in the other side of our Galaxy

Red supergiant stars (RSGs) are massive stars in a late stage of evolution, crucial for understanding stellar life cycles and Galactic structure. However, RSGs on the far side of our Galaxy have been underexplored due to observational challenges. In this study, we introduce a novel method and present a new catalogue comprising 474 RSGs situated on the far side of the Milky Way, sourced from the OGLE-III catalogue of Variable Stars (OIII-CVS). The identification of these RSGs was made possible by analyzing the granulation parameters extracted from OGLE I-band time-series data and the stellar parameters from Gaia DR3. Additionally, we estimate the distances to these RSGs using an empirical relation between their characteristic amplitude, absolute magnitude, and intrinsic color, achieving a distance uncertainty of 13%. These newly identified RSGs are distributed at Galactocentric distances between 0 and 30kpc, and reside roughly 1 to 4kpc above and below the Galactic plane. This distribution provides new insights into the structure of the Milky Way, particularly at its outer boundaries. Our results reveal that the vertical distribution of these RSGs is consistent with the flare structure of the Galactic disk, confirming that the far side of the Milky Way exhibits a similar flaring pattern to the near side. This catalogue offers a valuable resource for future detailed studies of RSGs and contributes to a more comprehensive understanding of the Galactic structure and stellar evolution.

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arXiv2025

The Multi-wavelength Extinction Law and its Variation in the Coalsack Molecular Cloud Based on the Gaia, APASS, SMSS, 2MASS, GLIMPSE, and WISE Surveys

Accurate interpretation of observations relies on the interstellar dust extinction law, which also serves as a powerful diagnostic for probing dust properties. In this study, we investigate the multi-wavelength extinction law of the quiescent, starless molecular cloud Coalsack and explore its potential variation across different interstellar environments: the surrounding region, the nearby high Galactic latitude region, the inner dense region, and the inner diffuse region. Using a sample of 368,524 dwarf stars selected from Gaia DR3 as tracers, we establish the effective temperature Teff-intrinsic color relations to derive the intrinsic color indices and optical-mid-infrared (MIR) color excess (CE) for 20 bands. Linear fits to the CE-CE diagrams provide color excess ratios (CERs), which are subsequently converted into relative extinction. The resulting extinction curves for different environments exhibit steep slopes in the near-infrared (NIR) and flat profiles in the MIR. In the optical-NIR range, the Coalsack extinction law is consistent with R_V = 3.1 while in the MIR it follows R_V= 5.5 similar to the results of active star-forming clouds. At an angular resolution of 1.3', our extinction map reveals fine cloud structures. No correlation is found between R_V and E(B-V) for E(B-V) > 0.3 mag, implying a uniform optical extinction law in the Coalsack cloud. The derived average R_V value is 3.24.

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arXiv2025

Dependence of Multi-band Absolute Magnitudes and Color Indexes of the Tip of Red Giant Branch Stars on Metallicity in the Galactic Globular Clusters

The tip of red giant branch (TRGB) stars have attracted intensive attention in recent years because their $I$-band absolute magnitudes, $M_\rm I$, are often used for distance calibration in the Hubble constant measurements because of its almost independence on metallicity ([Fe/H]). However, a discrepancy exists between various studies and the theoretical stellar model predicts dependence of their luminosity on [Fe/H]. Here we present a careful study of the dependence of absolute magnitudes and color indexes on metallicity in optical and near-infrared bands. With the TRGB stars identified in 33 Galactic globular clusters by the reddest color in the $G_{\rm BP}-G_{\rm RP}$ vs. $G_{\rm RP}$ diagram, it is confirmed that $M_\rm I$ is almost constant of $-4.017 \pm 0.036 \pm 0.027$ mag when $[\rm Fe/H]<-1.2$, which would give $H_0=70.86\pm 1.2\pm0.9$ $\rm kms^{-1} Mp c^{-1}$ with this updated luminosity calibration for type Ia supernovae. However, for $[\rm Fe/H]>-1.2$, $M_\rm I$ is found to become fainter with lower metallicity, which would lead to a larger Hubble constant. In the optical $G_{\rm BP}, G_{\rm RP}$ and $V$ bands, the absolute magnitude of TRGB stars tends to increase with metallicity, while in the infrared $J, H$, and $K_{\rm S}$ bands, the variation with metallicity shows an inverse tendency. In addition, the analytical relations of the color indexes with metallicity are presented, which have smaller dispersion than those derived for the corresponding absolute magnitudes.

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arXiv2025

The Age-velocity Dispersion Relations of the Galactic Disk as Revealed by the LAMOST-Gaia Red Clump Stars

Using nearly 230,000 red clump (RC) stars selected from LAMOST and Gaia, we conduct a comprehensive analysis of the stellar age-velocity dispersion relations (AVRs) for various disk populations, within 5.0 $\leq$ $R$ $\leq$ 15.0 kpc and $|Z|$ $\leq$ 3.0 kpc. The AVRs of the whole RC sample stars are accurately described as $σ_{v}$ = $σ_{v,0}$ ($τ$ + 0.1)$^{β_{v}}$, with $β_{R}$, $β_ϕ$ and $β_{Z}$ displaying a global exponential decreasing trend with $R$, which may point to the difference in spatial distributions of various disk heating mechanisms. The measurements of $β$ $-$ $R$ for various disks suggest that the thin disk exhibits a radial dependence, with a global exponential decreasing trend in $β_{R}$ $-$ $R$ and $β_{Z}$ $-$ $R$, while $β_ϕ$ remains a nearly constant value (around 0.20$\sim$0.25) within 8.5 $\leq$ $R$ $\leq$ 11.5 kpc. The thick disk displays a global increasing trend in $β_{R}$ $-$ $R$, $β_ϕ$ $-$ $R$ and $β_{Z}$ $-$ $R$. These results indicate that the thin disk stars are likely heated by long-term heating from GMCs and spiral arms, while thick disk stars are likely heated by some violent heating process from merger and accretion, and/or formed by the inside-out and upside-down star formation scenarios, and/or born in the chaotic mergers of gas-rich systems and/or turbulent ISM. Our results also suggest that the disk perturbation by a recent minor merger from Sagittarius may have occurred within 3.0 Gyr.

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arXiv2024

Searching for Galactic Red Supergiants with Gaia RVS Spectra

Red supergiants (RSGs) are essential to understanding the evolution and the contribution to the interstellar medium of massive stars. However, the number of identified RSGs within the Milky Way is still limited mainly due to the difficulty of measuring stellar extinction and distance. The release of approximately one million RVS spectra in Gaia DR3 presents new opportunity for identifying Galactic RSGs, because the equivalent width of the calcium triplet lines (EW(CaT)) in the spectra is an excellent indicator of stellar surface gravity. This work uses the RVS spectra with signal-to-noise ratio (SNR) greater than 100 to search for the Galactic RSGs. The dwarf stars and red giants are removed and the RSG candidates are selected by the location in the EW(CaT) vs. BP-RP diagram. The early-type RSG candidates (K0-M2) are then identified by BP-RP > 1.584 and EW(CaT) > 1.1 nm. To identify late-type RSG candidates (after M2), the criteria of the average equivalent widths of TiO in the XP spectra (EW(TiO)) > 10 nm, the color index K-W3 < 0.5 and the period-amplitude sequence from Gaia DR3 LPV catalog are further applied to reduce the contamination of late-type red giants and asymptotic giant branch stars. This method yields 30 early-type (K0-M2) and 6196 late-type (after M2) RSG candidates, which is a significant increase to the present Galactic RSG sample. The application of this approach to the spectra with SNR > 50 results in 48 early-type and 11,491 late-type RSG candidates. This preliminary analysis paves the way for more extensive research with Gaia DR4 when larger spectral datasets are expected to significantly enhance our understanding of Galactic RSG populations.

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arXiv2024

A New Approach to Identifying Red Supergiant Stars in Metal-poor Galaxies: A Case Study of NGC 6822

A complete sample of red supergiant stars (RSGs) is important for studying their properties. Identifying RSGs in extragalatic field first requires removing the Galactic foreground dwarfs. The color-color diagram (CCD) method, specifically using $r-z/z-H$ and $J-H/H-K$, has proven successful in several studies. However, in metal-poor galaxies, faint RSGs will mix into the dwarf branch in the CCD and would be removed, leading to an incomplete RSG sample. This work attempts to improve the CCD method in combination with the Gaia astrometric measurement to remove foreground contamination in order to construct a complete RSG sample in metal-poor galaxies. The empirical regions of RSGs in both CCDs are defined and modified by fitting the locations of RSGs in galaxies with a range of metallicity. The metal-poor galaxy NGC 6822 is taken as a case study for its low metallicity ([Fe/H] $\approx$ -1.0) and moderate distance (about 500 kpc). In the complete sample, we identify 1,184 RSG, 1,559 oxygen-rich AGB (O-AGBs), 1,075 carbon-rich AGB (C-AGBs), and 140 extreme AGB (x-AGBs) candidates, with a contamination rate of approximately 20.5%, 9.7%, 6.8%, and 5.0%, respectively. We also present a pure sample, containing only the sources away from the dwarf branch, which includes 843 RSG, 1,519 O-AGB, 1,059 C-AGB, and 140 x-AGB candidates, with a contamination rate of approximately 6.5%, 8.8%, 6.1%, and 5.0%, respectively. About 600 and 450 RSG candidates are newly identified in the complete and pure sample, respectively, compared to the previous RSG sample in NGC 6822.

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arXiv2024

The Galactic Disk North-south Asymmetry in Metallicity May Be A New Tracer for the Disk Warp

Galactic disk warp has been widely characterized by stellar distributions and stellar kinematics but has not been traced by stellar chemistry. Here, we use a sample with over 170,000 red clump (RC) stars selected from LAMOST and APOGEE first to establish a correlation between the north-south asymmetry in metallicity ([Fe/H]) and the disk warp. Our results indicate that the height of the [Fe/H] mid-plane for the whole RC sample stars is accurately described as $Z_{w}$ = 0.017 ($R$ $-$ 7.112)$^{2}$ sin($ϕ$ $-$ 9.218). This morphology aligns closely with the warp traced by Cepheids, suggesting that the disk north-south asymmetry in [Fe/H] may serve as a new tracer for the Galactic warp. Our detailed analysis of the young/thin disk stars of this RC sample suggests that its warp is well-modeled as $Z_{w}$ = 0.016 ($R$ $-$ 6.507)$^{2}$ sin($ϕ$ $-$ 4.240), indicating that the line of node (LON) of the Galactic warp is oriented at 4.240$_{-1.747}^{+1.641}$ degree.

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arXiv2024

The Flattest Infrared Extinction Curve in Four Isolated Dense Molecular Cloud Cores

The extinction curve of interstellar dust in the dense molecular cloud cores is crucial for understanding dust properties, particularly size distribution and composition. We investigate the infrared extinction law in four nearby isolated molecular cloud cores, L429, L483, L673, and L1165, across the 1.2 - 8.0 $μ$m wavelength range, using deep near-infrared (NIR) and mid-infrared (MIR) photometric data from UKIDSS and Spitzer Space Telescope. These observations probe an unprecedented extinction depth, reaching $A_V\sim$ 40-60 mag in these dense cloud cores. We derive color-excess ratios $E(K-λ)/E(H-K)$ by fitting color-color diagrams of $(K-λ)$ versus $(H-K)$, which are subsequently used to calculate the extinction law $A_λ/A_K$. Our analysis reveals remarkably similar and exceptionally flat infrared extinction curves for all four cloud cores, exhibiting the most pronounced flattening reported in the literature to date. This flatness is consistent with the presence of large dust grains, suggesting significant grain growth in dense environments. Intriguingly, our findings align closely with the Astrodust model for a diffuse interstellar environment proposed by Hensley \& Draine. This agreement between dense core observations and a diffuse medium model highlights the complexity of dust evolution and the need for further investigation into the processes governing dust properties in different interstellar environments.

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arXiv2024

Searching for radio late-type dwarf stars in the GLEAM-X DR1 catalog

We have developed a new method of multi-wavelength data combination for the search of late-type radio dwarfs, and have put it into practice using GLEAM-X DR1 data. The initial sample is selected by cross-matching the Gaia/DR3 objects with the probability of being a star no less than 99$\%$, and removing the extragalactic objects assigned by the SIMBAD database. The late-type dwarf stars are judged according to their location in the $(BP-RP)_0/M_{\rm G}$ color-magnitude diagram and in the $(J-H)_0/(K-W1)_0$ near-infrared color-color diagram. Furthermore, stellar activity is searched by ultraviolet excess in the GALEX/NUV band and the Rossby number in the TESS light curves. In total, 12 stars are found to be late-type dwarf stars associated with radio source, which is consisted of five stars with the UV excess and seven stars with the Rossby number less than 0.13. Three of these 12 stars are previously studied to be associated with radio objects. All these 12 stars are considered to be reliable counterparts of radio sources.

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arXiv2024

Extinction of Taurus, Orion, Perseus and California Molecular Clouds Based on the LAMOST, 2MASS, and Gaia Surveys II: The Extinction Law

The extinction law from ultraviolet (UV) to infrared (IR) (0.2-24 $μ$m) is determined by relying on the blue-edge method and color excess ratios for some nearby molecular clouds, from low mass star forming region to massive star forming region. The observational data are collected from nine photometric surveys, along with stellar parameters from the APOGEE and LAMOST spectroscopic surveys. Within the uncertainties, the optical ratio of selective to total extinction ($R_{G_{BP}}$) does not vary substantially across the clouds, irrespective of the density, specifically $R_{G_{BP}} =2.302\pm0.027$, where $R_{G_{BP}} \equiv A_{G_{BP}}/E_{G_{BP},G_{RP}}$. The IR extinction law is consistent with \citet{Wang19_law}. The extinction law in the UV band is compromised by the shallow depth with $A_{V} \leq 2$ mag and is hard to describe by one parameter $R$. In addition, the extinction in the WISE/W1 band is significantly larger than in the Spitzer/IRAC1 band in the dense regions, which is attributed to the ice water absorption.

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arXiv2024

Mass-loss Rate of Highly Evolved Stars in the Magellanic Clouds

Asymptotic giant branch stars (AGBs) and red supergiant stars (RSGs) exhibit significant mass loss phenomena and are considered important sources of interstellar dust. In this work, we employed an uniform method of spectral energy distribution fitting to analyze a large, and hence statistically significant, sample of approximately 40,000 RSGs and AGBs in the Magellanic Clouds (MCs), providing a new catalog of evolved stars that includes stellar parameters and dust properties. Our results reveal that the total dust-production rate (DPR) of the Large Magellanic Cloud is approximately $9.69\times10^{-6}\,\rm{M_{\odot }\, yr^{-1}}$, while it is around $1.75\times10^{-6}\,\rm{M_{\odot }\,yr^{-1}}$ for the Small Magellanic Cloud, with a few stars significantly contributing to the total DPR. No significant differences were observed in the contributions to DPR from carbon-rich and oxygen-rich (O-rich) evolved stars in the MCs. We explored the relations between stellar parameters (luminosity, infrared color, period, amplitude) and mass-loss rate (MLR) for evolved stars. A prominent turning point at $\log{(L/L_{\odot})} \approx 4.4$ appears in the luminosity-MLR diagram of RSGs, potentially related to the mass-loss mechanism of RSGs. The luminosity-MLR relation of AGBs is highly scattered. The DPR of AGBs shows a clear change with pulsation period and amplitude, with DPR exhibiting a drastic increase at pulsation periods of approximately 300 days and I-band amplitudes greater than 0.5 mag. Metallicity has some impact on the DPR of O-rich stars, with lower metallicity seeming to result in lower mean DPR and a higher proportion of optically thin stars.

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arXiv2024

Identification and distance measurement of dust clouds at high latitude by a clustering hierarchical algorithm

We present a catalog of dust clouds at high Galactic latitude based on the Planck 857 GHz dust emission data. Using a clustering hierarchical algorithm, 315 dust cloud at high Galactic latitudes are identified. Additionally, using the optical and ultraviolet extinction of 4 million and 1 million stars, respectively, provided by Sun et al., we derive the distances and physical properties for 190 high Galactic latitude dust clouds and the ultraviolet excess ratios for 165 of them. Through the study of color excess ratios, this work confirms that molecular clouds with large Galactic distances and low extinction likely have a higher proportion of small-sized dust grains. In addition, clouds with well-defined distances in the catalog are used to trace the local bubble, showing good consistency with the boundary of the local bubble from the literature.

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arXiv2024

Data-driven stellar intrinsic colors and dust reddenings for spectro-photometric data: From the blue-edge method to a machine-learning approach

Intrinsic colors (ICs) of stars are essential for the studies on both stellar physics and dust reddening. In this work, we developed an XGBoost model to predict the ICs with the atmospheric parameters $T_{\rm eff}$, ${\rm log}\,g$, and $\rm [M/H]$. The model was trained and tested for three colors at Gaia and 2MASS bands with 1,040,446 low-reddening sources. The atmospheric parameters were determined by the Gaia DR3 GSP-phot module and were validated by comparing with APOGEE and LAMOST. We further confirmed that the biases in GSP-phot parameters, especially for $\rm [M/H]$, do not present a significant impact on the IC prediction. The generalization error of the model estimated by the test set is 0.014 mag for $(G_{\rm BP}\,{-}\,G_{\rm RP})_0$, 0.050 mag for $(G_{\rm BP}\,{-}\,K_{\rm S})_0$, and 0.040 mag for $(J\,{-}\,K_{\rm S})_0$. The model was applied to a sample containing 5,714,528 reddened stars with stellar parameters from Andrae et al. (2023) to calculate ICs and reddenings. The high consistency in the comparison of $E(J\,{-}\,K_{\rm S})$ between our results and literature values further validates the accuracy of the XGBoost model. The variation of $E(G_{\rm BP}\,{-}\,K_{\rm S})/E(G_{\rm BP}\,{-}\,G_{\rm RP})$, a representation of the extinction law, with Galactic longitude is found on large scales. This work preliminarily presents the feasibility and the accuracy of the machine-learning approach for IC and dust reddening calculation, whose products could be widely applied to spectro-photometric data. The data sets and trained model can be accessed via \url{https://doi.org/10.5281/zenodo.12787594}. The models for more bands will be completed in the following works.

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arXiv2024

Probing the distinct extinction law of the Pillars of Creation in M16 with JWST

Investigating the extinction law in regions of high dust extinction, such as the Pillars of Creation within the M16 region, is crucial for understanding the densest parts of the interstellar medium (ISM). In this study, we utilize observations from the Near-Infrared Camera (NIRCam) and the Mid-Infrared Instrument (MIRI) onboard the James Webb Space Telescope (JWST) to analyze the color-excess ratios $E(F090W-λ)/E(F090W-F200W)$ across a wavelength range of $0.9-7.7\,μ\mathrm{m}$. Our method involves performing linear regression on color-color diagrams to derive these ratios. The enhanced detection capabilities of JWST data allow us to probe the distinct extinction law to the densest regions in M16 corresponding to an extinction depth up to $A_V \sim 60$\,mag. Remarkably, the resultant color-excess ratio curve exhibits a flatter profile than predicted by typical dust extinction models with $R_V = 5.5$ for dense ISM environments. Moreover, we observe that the mid-infrared (MIR) extinction law diverges from the near-infrared (NIR) power-law, showing a tendency for the slope to flatten as the wavelength increases. These findings have significant implications for our understanding of the dust properties in dense interstellar environments.

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arXiv2024

Modeling of Granulation in Red Supergiants in the Magellanic Clouds with the Gaussian Process Regressions

The granulation of red supergiants (RSGs) in the Magellanic Clouds are systematically investigated by combining the latest RSGs samples and light curves from the Optical Gravitational Lensing Experiment and the All-Sky Automated Survey for Supernovae. The present RSGs samples are firstly examined for foreground stars and possible misidentified sources, and the light curves are sequentially checked to remove the outliers by white noise and photometric quality. The Gaussian Process regression is used to model the granulation, and the Markov Chain Monte Carlo is applied to derive the granulation amplitude $σ$ and the period of the undamped oscillator $ρ$, as well as the damping timescale $τ$. The dimensionless quality factor $Q$ is then calculated through $Q=πτ/ρ$. RSGs around $Q = 1/\sqrt{2}$ are considered to have significant granulation signals and are used for further analysis. Combining granulation parameters with stellar parameters, robust scaling relations for the timescale $ρ$ are established, while the scaling relations for amplitude $σ$ are represented by a piecewise function, possibly related to the tendency of amplitudes in faint RSGs to converge towards a certain value. Comparing results between the SMC and LMC confirms that amplitudes and timescales become larger with metallicity. In examining the scaling relations between the two galaxies, it is found that $ρ$ is nearly independent of metallicity, whereas $σ$ is more significantly affected by metallicity. The Gaussian Process method is compared with the periodogram fitting of the granulations, and the advantages of either are discussed.

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