Accurate measurements of stellar positions and velocities are crucial for studying galactic and stellar dynamics.W aim to create a Cartesian catalog from Gaia DR3 to serve as a high-precision database for further rese...Accurate measurements of stellar positions and velocities are crucial for studying galactic and stellar dynamics.W aim to create a Cartesian catalog from Gaia DR3 to serve as a high-precision database for further research using stellar coordinates and velocities.To avoid the negative parallax values,we select 31,129,169 sources in Gaia DR3with radial velocity,where the fractional parallax error is less than 20%(0<σ■/■<0.2).To select the mos accurate and efficient method of propagating mean and covariance,we use the Monte Carlo results with 10^(7)samples (MC7) as the benchmark,and compare the precision of linear,second-order,and Monte Carlo erro propagation methods.By assessing the accuracy of propagated mean and covariance,we observe that second-orde error propagation exhibits mean deviations of at most 0.5%compared to MC7,with variance deviations of up to10%.Overall,this outperforms linear transformation.Though the Monte Carlo method with 10^(4) samples (MC4) i an order of magnitude slower than second-order error propagation,its covariance propagation accuracy reaches 1%whenσ■/■is below 15%.Consequently,we employ second-order error propagation to convert the mean astrometry and radial velocity into Cartesian coordinates and velocities in both equatorial and galactic systems fo30 million Gaia sources,and apply MC4 for covariance propagation.The Cartesian catalog and source code ar provided for future applications in high-precision stellar and galactic dynamics.展开更多
This study addresses the critical technical need to enhance the 1–10 day prediction accuracy of polar motion (PM)in satellite autonomous navigation and deep space exploration,with a focus on optimizing the convolutio...This study addresses the critical technical need to enhance the 1–10 day prediction accuracy of polar motion (PM)in satellite autonomous navigation and deep space exploration,with a focus on optimizing the convolution input accuracy within the least squares and autoregression with effective angular momentum (LS+AR+EAM) method.Through theoretical derivation and numerical experiments,we identify the significant impact of the iterative mechanism of the convolution input in the Liouville equation on PM prediction accuracy.On one hand,it clearly states that the initial step of convolution iteration should begin today using today’s daily data,rather than relying on the iterative convolution result from the previous step.On the other hand,due to the requirement for the previous PM,previous geodetic angular momentum (GAM),and current GAM in convolution input,several GAM predictions are constructed using IGS ultra-rapid 6 hr resolution data.Additionally,a hybrid method is used to obtain multiple EAM predictions.By integrating these predictions,the range of prediction errors is effectively constrained.The hindcast results,submitted before 20:00 UTC every Wednesday during the official interval of the second Earth Orientation Parameters Prediction Comparison Campaign (2nd EOP PCC),show that the proposed method improved the mean absolute error (MAE) over the first seven days compared to the first-place method(ID136),with improvements of 51.9%,32.0%,28.5%,20.9%,19.2%,17.2%,and 17.0%in the X direction,and20.6%,16.2%,14.4%,12.8%,8.7%,3.1%,and 3.0% in the Y direction.Furthermore,extending the statistical range from 2016/1/6 to 2022/12/28,the proposed method yields MAE values of (0.165,0.137),(0.735,0.505),and (1.874,1.238) mas for days 1,5,and 10,respectively,outperforming the official predictions by IERS or USNO,which are (0.255,0.194),(1.534,1.110),and (2.875,1.877) mas.This not only validates the stability of the proposed method but also demonstrates its direct applicability in real-world engineering applications.展开更多
We have collected a catalog of 1095 debris disks with properties and classification(resolved,planet,gas)information.From the catalog,we defined a less biased sample with 612 objects and presented the distributions of ...We have collected a catalog of 1095 debris disks with properties and classification(resolved,planet,gas)information.From the catalog,we defined a less biased sample with 612 objects and presented the distributions of their stellar and disk properties to search for correlations between disks and stars.We found debris disks were widely distributed from B to M-type stars while planets were mostly found around solar-type stars,gases were easier to detect around early-type stars and resolved disks were mostly distributed from A to G-type stars.The fractional luminosity dropped off with stellar age and planets were mostly found around old stars while gas-detected disks were much younger.The dust temperature of both one-belt systems and cold components in two-belt systems increased with distance while decreasing with stellar age.In addition,we defined a less biased planet sample with 211 stars with debris disks but no planets and 35 stars with debris disks and planets and found the stars with debris disks and planets had higher metallicities than stars with debris disks but no planets.Among the 35 stars with debris disks and planets,we found the stars with disks and cool Jupiters were widely distributed with age from 10 Myr to 10 Gyr and metallicity from-1.56 to 0.28 while the other three groups tended to be old(>4Gyr)and metal-rich(>-0.3).In addition,the eccentricities of cool Jupiters are distributed from 0 to 0.932,wider than the other three types of planets(<0.3).展开更多
基金supported by the National Key R&D Program of China,No.2024YFA1611801 and No.2024YFC2207800the National Natural Science Foundation of China (NSFC) under Grant No.12473066supported by Shanghai Jiao Tong University 2030 Initiative.W.W.is supported by NSFC (Grant Nos.12022307 and 12273021)。
文摘Accurate measurements of stellar positions and velocities are crucial for studying galactic and stellar dynamics.W aim to create a Cartesian catalog from Gaia DR3 to serve as a high-precision database for further research using stellar coordinates and velocities.To avoid the negative parallax values,we select 31,129,169 sources in Gaia DR3with radial velocity,where the fractional parallax error is less than 20%(0<σ■/■<0.2).To select the mos accurate and efficient method of propagating mean and covariance,we use the Monte Carlo results with 10^(7)samples (MC7) as the benchmark,and compare the precision of linear,second-order,and Monte Carlo erro propagation methods.By assessing the accuracy of propagated mean and covariance,we observe that second-orde error propagation exhibits mean deviations of at most 0.5%compared to MC7,with variance deviations of up to10%.Overall,this outperforms linear transformation.Though the Monte Carlo method with 10^(4) samples (MC4) i an order of magnitude slower than second-order error propagation,its covariance propagation accuracy reaches 1%whenσ■/■is below 15%.Consequently,we employ second-order error propagation to convert the mean astrometry and radial velocity into Cartesian coordinates and velocities in both equatorial and galactic systems fo30 million Gaia sources,and apply MC4 for covariance propagation.The Cartesian catalog and source code ar provided for future applications in high-precision stellar and galactic dynamics.
基金supported by the Astrometric Reference Frame project (Grant No.JZZX-0102)the National Natural Science Foundation of China (NSFC,Grant Nos.12473069,12233010,and 12173070)the Natural Science Foundation of Shanghai (Grant No.24ZR1476800)。
文摘This study addresses the critical technical need to enhance the 1–10 day prediction accuracy of polar motion (PM)in satellite autonomous navigation and deep space exploration,with a focus on optimizing the convolution input accuracy within the least squares and autoregression with effective angular momentum (LS+AR+EAM) method.Through theoretical derivation and numerical experiments,we identify the significant impact of the iterative mechanism of the convolution input in the Liouville equation on PM prediction accuracy.On one hand,it clearly states that the initial step of convolution iteration should begin today using today’s daily data,rather than relying on the iterative convolution result from the previous step.On the other hand,due to the requirement for the previous PM,previous geodetic angular momentum (GAM),and current GAM in convolution input,several GAM predictions are constructed using IGS ultra-rapid 6 hr resolution data.Additionally,a hybrid method is used to obtain multiple EAM predictions.By integrating these predictions,the range of prediction errors is effectively constrained.The hindcast results,submitted before 20:00 UTC every Wednesday during the official interval of the second Earth Orientation Parameters Prediction Comparison Campaign (2nd EOP PCC),show that the proposed method improved the mean absolute error (MAE) over the first seven days compared to the first-place method(ID136),with improvements of 51.9%,32.0%,28.5%,20.9%,19.2%,17.2%,and 17.0%in the X direction,and20.6%,16.2%,14.4%,12.8%,8.7%,3.1%,and 3.0% in the Y direction.Furthermore,extending the statistical range from 2016/1/6 to 2022/12/28,the proposed method yields MAE values of (0.165,0.137),(0.735,0.505),and (1.874,1.238) mas for days 1,5,and 10,respectively,outperforming the official predictions by IERS or USNO,which are (0.255,0.194),(1.534,1.110),and (2.875,1.877) mas.This not only validates the stability of the proposed method but also demonstrates its direct applicability in real-world engineering applications.
基金supported in part by the National Natural Science Foundation of China(NSFC,Nos.U1631109,11703093 and U2031120)supported in part by the Special Natural Science Fund of Guizhou University(Grant No.201911A)the First-class Physics Promotion Programme(2019)of Guizhou University。
文摘We have collected a catalog of 1095 debris disks with properties and classification(resolved,planet,gas)information.From the catalog,we defined a less biased sample with 612 objects and presented the distributions of their stellar and disk properties to search for correlations between disks and stars.We found debris disks were widely distributed from B to M-type stars while planets were mostly found around solar-type stars,gases were easier to detect around early-type stars and resolved disks were mostly distributed from A to G-type stars.The fractional luminosity dropped off with stellar age and planets were mostly found around old stars while gas-detected disks were much younger.The dust temperature of both one-belt systems and cold components in two-belt systems increased with distance while decreasing with stellar age.In addition,we defined a less biased planet sample with 211 stars with debris disks but no planets and 35 stars with debris disks and planets and found the stars with debris disks and planets had higher metallicities than stars with debris disks but no planets.Among the 35 stars with debris disks and planets,we found the stars with disks and cool Jupiters were widely distributed with age from 10 Myr to 10 Gyr and metallicity from-1.56 to 0.28 while the other three groups tended to be old(>4Gyr)and metal-rich(>-0.3).In addition,the eccentricities of cool Jupiters are distributed from 0 to 0.932,wider than the other three types of planets(<0.3).
