Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： We systematically searched for open clusters in the solar neighborhood within 500 pc using pyUPMASK and HDBSCAN clustering algorithms based on {\it Gaia} DR3. Taking into consideration that the physical size for most open clusters is less than 50 pc, we adopted a slicing approach for different distance shells and identified 324 neighboring open clusters, including 223 reported open clusters and 101 newly discovered open clusters (named as OCSN, Open Cluster of Solar Neighborhood). Our discovery has increased the number of open clusters in the solar neighborhood by about 45\%. In this work, larger spatial extents and more member stars were attained for our cluster sample. We provided the member stars and the membership probabilities through the pyUPMASK algorithm for each cluster and derived their astrophysical, age, and structural parameters.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： With the help of Gaia data, it is noted that in addition to the core components, there are low-density outer halo components in the extended region of open clusters. To study the extended structure beyond the core radius of the cluster ($\sim$ 10 pc), based on Gaia EDR3 data, taking up to 50 pc as the searching radius, we use the pyUPMASK algorithm to re-determine the member stars of the open cluster within 1-2 kpc. We obtain the member stars of 256 open clusters, especially those located in the outer halo region of open clusters. Furthermore, we find that most open clusters' radial density profile in the outer region deviates from the King's profile. To better describe the internal and external structural characteristics of open clusters, we propose a double components model for description: core components with King model distribution and outer halo components with logarithmic Gaussian distribution, and then suggest using four radii ( $r_c$, $r_t$, $r_o$, $r_e$) for describing the structure and distribution profile of star clusters, where $r_t$ and $r_e$ represent the boundaries of core components and outer halo components respectively. Finally, we provide a catalog of 256 clusters with structural parameters. In addition, our study shows the sizes of these radii are statistically linear related, which indicates that the inner and outer regions of the cluster are interrelated and follow similar evolutionary processes. Further, we show that the structure of two components can be used to better trace the cluster evolution properties in different stages.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： COIN-Gaia 13 is a newly discovered open cluster revealed by Gaia DR2 data. It is a nearby open cluster with a distance of about 513 pc. Combined with the five-dimensional astrometric data of Gaia EDR3 with higher accuracy, we use the membership assignment algorithm (pyUPMASK) to determine the membership of COIN-Gaia 13 in a large extended spatial region. The cluster has found 478 candidate members. After obtaining reliable cluster members, we further study its basic properties and spatial distribution. Our results show that there is an obvious extended structure of the cluster in the X-Y plane. This elongated structure is distributed along the spiral arm, and the whole length is about 270 pc. The cluster age is 250 Myr, the total mass is about 439 M$_\odot$, and the tidal radius of the cluster is about 11 pc. Since more than half of the member stars (352 stars) are located outside twice the tidal radius, it is suspected that this cluster is undergoing the dynamic dissolution process. Furthermore, the spatial distribution and kinematic analysis indicate that the extended structure in COIN-Gaia 13 is more likely to be caused by the differential rotation of the Galaxy.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Chenyu He
Weijia Sun
Chengyuan Li
Lu Li
Zhengyi Shao
Jing Zhong
Li Chen
Richard de Grijs
Baitian Tang
Songmei Qin
Zara Randriamanakoto
Abstract： In addition to the extended main-sequence turnoffs widely found in young and intermediate-age (~ 600 Myr-2 Gyr-old) star clusters, some younger clusters even exhibit split main sequences (MSs). Different stellar rotation rates are proposed to account for the bifurcated MS pattern, with red and blue MSs (rMS and bMS) populated by fast and slowly rotating stars, respectively. Using photometry from Gaia Early Data Release 3, we report a Galactic open cluster with a bifurcated MS, NGC 2422 ( ~ 90 Myr). We exclude the possibilities that the bifurcated MS pattern is caused by photometric noise or differential reddening. We aim to examine if stellar rotation can account for the split MSs. We use spectra observed with the Canada-France-Hawaii Telescope and the Southern African Large Telescope, and directly measured v sin i, the projected rotational velocities, for stars populating the bMS and rMS. We find that their v sin i values are weakly correlated with their loci in the color-magnitude diagram because of contamination caused by a large fraction of rMS stars with low projected rotational velocities. Based on the spectral energy distribution fitting method, we suggest that these slowly rotating stars at the rMS may hide a binary companion, which breaks the expected v sin i-color correlation. Future time-domain studies focusing on whether these slowly rotating stars are radial velocity variables are crucial to test the roles of stellar rotation and binarity in generating the split MSs.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： We systematically searched for open clusters in the solar neighborhood within 500 pc using pyUPMASK and HDBSCAN clustering algorithms based on {\it Gaia} DR3. Taking into consideration that the physical size for most open clusters is less than 50 pc, we adopted a slicing approach for different distance shells and identified 324 neighboring open clusters, including 223 reported open clusters and 101 newly discovered open clusters (named as OCSN, Open Cluster of Solar Neighborhood). Our discovery has increased the number of open clusters in the solar neighborhood by about 45\%. In this work, larger spatial extents and more member stars were attained for our cluster sample. We provided the member stars and the membership probabilities through the pyUPMASK algorithm for each cluster and derived their astrophysical, age, and structural parameters.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Xiaoting Fu
Angela Bragaglia
Chao Liu
Huawei Zhang
Yan Xu
Ke Wang
Zhi-Yu Zhang
Jing Zhong
Jiang Chang
Lu Li
Li Chen
Yang Chen
Fei Wang
Eda Gjergo
Chun Wang
Nannan Yue
Xi Zhang
Abstract： Open Clusters are born and evolve along the Milky Way plane, on them is imprinted the history of the Galactic disc, including the chemical and dynamical evolution. Chemical and dynamical properties of open clusters can be derived from photometric, spectroscopic, and astrometric data of their member stars. Based on the photometric and astrometric data from the Gaia mission, the membership of stars in more than 2000 Galactic clusters has been identified in the literature. The chemical and kinematical properties, however, are still poorly known for many of these clusters. In synergy with the large spectroscopic survey LAMOST (data release 8) and Gaia (data release 2), we report a new comprehensive catalogue of 386 open clusters. This catalogue has homogeneous parameter determinations of radial velocity, metallicity, and dynamical properties, such as orbit, eccentricity, angular momenta, total energy, and 3D Galactic velocity. These parameters allow the first radial velocity determination and the first spectroscopic [Fe/H] determination for 44 and 137 clusters, respectively. The metallicity distribution of majority clusters shows falling trends in the parameter space of the Galactocentric radius, the total energy, and the Z component of angular momentum -- except for two old groups that show flat tails in their own parameter planes. Cluster populations of ages younger and older than 500 Myrs distribute diversely on the disc. The latter has a spatial consistency with the Galactic disc flare. The 3-D spatial comparison between very young clusters (< 100 Myr) and nearby molecular clouds revealed a wide range of metallicity distribution along the Radcliffe gas cloud wave, indicating a possible inhomogeneous mixing or fast star formation along the wave. This catalogue would serve the community as a useful tool to trace the chemical and dynamical evolution of the Milky Way.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： We report 541 new open cluster candidates in Gaia EDR3 through revisiting the cluster results from an earlier analysis of the Gaia DR2, which revealed nearly a thousand open cluster candidates in the solar neighborhood (mostly d < 3 kpc) resideing at Galactic latitudes |b| < 20 degrees. A subsequent comparison with lists of known clusters shows a large increases of the cluster samples within 2 kpc from the Sun. We assign membership probabilities to the stars through the open source pyUPMASK algorithm, and also estimate the physical parameters through isochrone fitting for each candidate. Most of the new candidates show small total proper motion dispersions and clear features in the color-magnitude diagrams. Besides, the metallicity gradient of the new candidates is consistent with those found in the literature. The cluster parameters and member stars are available at CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via https://cdsarc.unistra.fr/viz-bin/cat/J/ApJS. The discovery of these new objects shows that the open cluster samples in Gaia data is still not complete, and more discoveries are expected in the future researches.
Peer Review Status:Awaiting Review
Subjects: Optics >> Quantum optics submitted time 2023-02-19
Wu-Zhen Li
Chen Yang
Zhi-Yuan Zhou
Yan Li
Yin-Hai Li
Su-Jian Niu
Zheng Ge
Li Chen
Guang-Can Guo
Bao-Sen Shi
Abstract： The change in the relative phase between two light fields serves as a basic principle for the measurement of the physical quantity that guides this change. It would therefore be highly advantageous if the relative phase could be amplified to enhance the measurement resolution. One well-known method for phase amplification involves the use of the multi-photon number and path entangled state known as the NOON state; however, a high-number NOON state is very difficult to prepare and is highly sensitive to optical losses. Here we propose and experimentally demonstrate in principle a phase amplifier scheme with the assistance of a harmonic generation process. The relative phase difference between two polarization modes in a polarized interferometer is amplified coherently four times with cascaded second-harmonic generation processes. We demonstrate that these amplification processes can be recycled and therefore have the potential to realize much higher numbers of multiple amplification steps. The phase amplification method presented here shows considerable advantages over the method based on NOON states and will be highly promising for use in precision optical measurements.
Peer Review Status:Awaiting Review
Subjects: Biology >> Biochemistry submitted time 2020-02-12
Yingxia Liu
Cong Zhang
Fengming Huang
Yang Yang
Fuxiang Wang
Jing Yuan
Zheng Zhang
Yuhao Qin
Xiaoyun Li
Dandan Zhao
Shunwang Li
Shuguang Tan
Zhaoqin Wang
Jinxiu Li
Chenguang Shen
Jianming Li
Ling Peng
Weibo Wu
Mengli Cao
Li Xing
Abstract： A recent outbreak of pneumonia in Wuhan, China was caused by 2019 novel coronavirus (2019-nCoV). Here we reported 12 patients with 2019-nCoV infections in Shenzhen, China; all of them developed pneumonia and half developed acute respiratory distress syndrome (ARDS). We demonstrated the plasma cytokine profiles of these 12 patients. Thirty-eight out of 48 cytokines measured in the plasmas of 2019-nCoV infected patients were significantly elevated compared to healthy individuals. Seventeen cytokines were linked to 2019-nCoV load. Fifteen cytokines, M-CSF, IL-10, IFN-2, IL-17, IL-4, IP-10, IL-7, IL-1ra, G-CSF, IL-12, IFN-γ, IL-1, IL-2, HGF, and PDGF-BB, were strongly associated with lung injury Murray score, and could predict disease severity of 2019-nCoV infections according to area under the curve (AUC) of the receiver-operating characteristics (ROC) calculations. Our results suggest that 2019-nCoV infections trigger extensive changes in a wide array of cytokines, some of these cytokines could be potential biomarkers of disease severity of 2019-nCoV infections. These findings improve our understanding of the immunopathologic mechanisms of this emerging and still evolving disease and suggest that modulators of cytokine responses could play a therapeutic role in combating the disease. " "
Peer Review Status:Awaiting Review
Subjects: Biology >> Biochemistry submitted time 2020-02-08
Yingxia Liu
Yang Yang
Cong Zhang
Fengming Huang
Fuxiang Wang
Jing Yuan
Zhaoqin Wang
Jingxiu Li
Jianming Li
Cheng Feng
Zheng Zhang
Lifei Wang
Ling Peng
Li Chen
Yuhao Qin
Dandan Zhao
Shuguang Tan
Lu Yin
Jun Xu
Congzhao Zhou
Abstract： The outbreak of the 2019-nCoV infection began in December 2019 in Wuhan, Hubei province, and rapidly spread to many provinces in China as well as other countries. Here we report the epidemiological, clinical, laboratory, and radiological characteristics, as well as potential biomarkers for predicting disease severity in 2019-nCoV-infected patients in Shenzhen, China. All 12 cases of the 2019-nCoV-infected patients developed pneumonia and half of them developed acute respiratory distress syndrome (ARDS). The most common laboratory abnormalities were hypoalbuminemia (ALB), lymphopenia, decreased percentage of lymphocytes (LYM) and neutrophils (NEU), elevated C-reactive protein (CRP) and lactate dehydrogenase (LDH), and decreased CD8 count. The viral load of 2019-nCoV detected from patient respiratory tracts was positively linked to lung disease severity. ALB, LYM, LYM (%), LDH, NEU (%) and CRP were highly correlated to the acute lung injury. Age, viral load, lung injury score, and blood biochemistry indexes, ALB, CRP, LDH, LYM (%), LYM, and NEU (%), may be predictors of disease severity. Moreover, the Angiotensin II level in the plasma sample from 2019-nCoV infected patients was markedly elevated and linearly associated to viral load and lung injury. Our results suggest a number of potential diagnosis biomarkers and angiotensin receptor blocker (ARB) drugs for potential repurposing treatment of 2019-nCoV infection.
Peer Review Status:Awaiting Review
Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology submitted time 2018-03-30
Jian Zhang
Xiaoying Qin
Di Li
Chunjun Song
Xiaoguang Zhu
Yongfei Liu
Hongxing Xin
Li Chen
Tianhua Zou
Abstract： Gd-doped compounds CuGa1-xGdxTe2 (0x0.02) incorporated with tellurium nanoparticles are synthesized by fusion method. Their thermoelectric properties are investigated in the temperature range of 300-800K. The results indicate that the synergistic effect of Gd-doping and Te incorporation remarkably enhances the thermoelectric performance of CuGaTe2. Specially, the thermal conductivity of the specimen CuGa0.98Gd0.02Te2/0.7vol.%Te reduces to 0.45 Wm-1K-1 at 684K, which is ~74% smaller than that of pure CuGaTe2 (=1.76 Wm-1K-1 at 684K) due to the incorporation of nanostructure Te. The thermoelectric figure of merit value (ZT) reaches 0.75 at 737K for the specimen CuGa0.99Gd0.01Te2/0.7vol.%Te, which is ~115% larger than that of pure CuGaTe2.
Peer Review Status:Awaiting Review
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. submitted time 2017-11-10
TiPei Li
ShaoLin Xiong
ShuangNan Zhang
FangJun Lu
LiMing Song
XueLei Cao
Zhi Chang
Gang Chen
Li Chen
TianXiang Chen
Yong Chen
YiBao Chen
YuPeng Chen
Wei Cui
WeiWei Cui
JingKang Deng
YongWei Dong
YuanYuan Du
MinXue Fu
GuanHua Gao
Abstract：Finding the electromagnetic (EM) counterpart of binary compact star merger, especially the binary neutron star (BNS) merger, is critically important for gravitational wave (GW) astronomy, osmology and fundamental physics. On Aug. 17, 2017, Advanced LIGO and Fermi/GBM independently triggered the first BNS merger, GW170817, and its high energy EM counterpart, GRB 170817A, respectively, resulting in a global observation campaign covering gamma-ray, X-ray, UV, optical, IR, radio as well as neutrinos. The High Energy X-ray telescope (HE) onboard Insight-HXMT (Hard X-ray Modulation Telescope) is the unique high-energy gamma-ray telescope that monitored the entire GW localization area and especially the optical counterpart (SSS17a/AT2017gfo) with very large collection area (~1000 cm2) and microsecond time resolution in 0.2-5 MeV. In addition, Insight-HXMT quickly implemented a Target of Opportunity (ToO) observation to scan the GW localization area for potential X-ray emission from the GW source. Although Insight-HXMT did not detect any significant high energy (0.2-5 MeV) radiation from GW170817, its observation helped to confirm the nexpected weak and soft nature of GRB 170817A. Meanwhile, Insight-HXMT/HE provides one of the most stringent constraints (~10-7 to 10-6 erg/cm2/s) for both GRB170817A and any other possible precursor or extended emissions in 0.2-5 MeV, which help us to better understand the properties of EM radiation from this BNS merger. Therefore the observation of Insight-HXMT constitutes an important chapter in the full context of multi-wavelength and multi-messenger observation of this historical GW event.
Peer Review Status:Awaiting Review
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