The melting curve of MgSiO3 perovskite was simulated using molecular dynamics method combining with the effective pair potentials under the lower mantle conditions. It was shown that the state equation simulated for M...The melting curve of MgSiO3 perovskite was simulated using molecular dynamics method combining with the effective pair potentials under the lower mantle conditions. It was shown that the state equation simulated for MgSiO3 perovskite is very successful in reproducing accurately the experimental data over a wide range of pressure. The pressure dependence of the simulated melting temperature of MgSiO3 perovskite is in agreement with the recent experimental data. The melting curve simulated for MgSiO3 is very steep at pressures below 60 GPa first, then it becomes smooth with increasing pressure. At the core mantle boundary pressure 135 GPa, MgSiO3 perovskite melts at 6500 K, which is significantly lower than that of the extrapolations of the experimental data from Zerr and Boehler.展开更多
t We present high spatial resolution X-ray spectroscopy of Tycho＇s supernova remnant （SNR） using observational data from Chandra. The whole remnant was divided into 26 × 27 regions, with each of them covering...t We present high spatial resolution X-ray spectroscopy of Tycho＇s supernova remnant （SNR） using observational data from Chandra. The whole remnant was divided into 26 × 27 regions, with each of them covering 20＂× 20＂. We selected 536 pixels with enough events to generate spectra and fit them with an absorbed two component non-equilibrium ionization model. We obtained maps of absorbing column density, weight-averaged temperature, ionization age and abundances for O, Ne, Mg, Si, S and Fe, with emission used to determine the weight. The abundance maps and the finding that Fe abundance is not correlated with any other element suggest that Fe is located at a smaller radius than other elements, supporting the onion shell model with emission from more massive elements peaking more toward the center. A tight correlation between Si and S abundances support both Si and S coming from explosive O-burning and/or incomplete Si-burning. O and Ne abundances show no correlation with any other element. Considering that O, Ne and Mg are all synthesized in the same process （C/Ne-burning）, we suggest that O/Ne/Mg might mix well with other elements during the explosion of the supernova and the expansion of the SNR.展开更多
基金Jointly Funded Project of the National Natural Science Foundation of China and the Civil Aviation Administration of China(U1333119)Project of the National Defense Basic Scientific Research Plan(JCKY2013605B002)+1 种基金Major Science and Technology Special Funding Projects of Zhejiang Province(2016C02G2100540)Scientific Research Project of the Zhejiang Provincial Education Department(Y201636110)~~
基金V. ACKN0WLEDGEMENTS This work was supported by the National Natural Science Foundation of China （No.10574096）, the Natural Science Foundation of Gansu Province of China （No.3ZS051-A25-027） and the Scientific Research Foundation of Education Bureau of Gansu Province of China （No.0410-01）.
文摘The melting curve of MgSiO3 perovskite was simulated using molecular dynamics method combining with the effective pair potentials under the lower mantle conditions. It was shown that the state equation simulated for MgSiO3 perovskite is very successful in reproducing accurately the experimental data over a wide range of pressure. The pressure dependence of the simulated melting temperature of MgSiO3 perovskite is in agreement with the recent experimental data. The melting curve simulated for MgSiO3 is very steep at pressures below 60 GPa first, then it becomes smooth with increasing pressure. At the core mantle boundary pressure 135 GPa, MgSiO3 perovskite melts at 6500 K, which is significantly lower than that of the extrapolations of the experimental data from Zerr and Boehler.
基金supported by the National Natural Science Foundation of China(NSFC,Grant No.11473023)Hunan Provincial Natural Science Foundation(2015JJ3124)
文摘t We present high spatial resolution X-ray spectroscopy of Tycho＇s supernova remnant （SNR） using observational data from Chandra. The whole remnant was divided into 26 × 27 regions, with each of them covering 20＂× 20＂. We selected 536 pixels with enough events to generate spectra and fit them with an absorbed two component non-equilibrium ionization model. We obtained maps of absorbing column density, weight-averaged temperature, ionization age and abundances for O, Ne, Mg, Si, S and Fe, with emission used to determine the weight. The abundance maps and the finding that Fe abundance is not correlated with any other element suggest that Fe is located at a smaller radius than other elements, supporting the onion shell model with emission from more massive elements peaking more toward the center. A tight correlation between Si and S abundances support both Si and S coming from explosive O-burning and/or incomplete Si-burning. O and Ne abundances show no correlation with any other element. Considering that O, Ne and Mg are all synthesized in the same process （C/Ne-burning）, we suggest that O/Ne/Mg might mix well with other elements during the explosion of the supernova and the expansion of the SNR.
