The purpose of this paper is to address the question:Using our knowledge of infrared planetary spectroscopy,what can we learn about the atmospheres of exoplanets?In a first part,a simplified classification of exoplane...The purpose of this paper is to address the question:Using our knowledge of infrared planetary spectroscopy,what can we learn about the atmospheres of exoplanets?In a first part,a simplified classification of exoplanets,assuming thermochemical equilibrium,is presented,based on their masses and their equilibrium temperatures,in order to propose some possible estimations about their atmospheric composition.In the second part,infrared spectra of planets are discussed,in order to see what lessons can be drawn for exoplanetary spectroscopy.In the last part,we consider the solar system as it would appear from a star located in the ecliptic plane.It first appears that the solar system(except in a few specific cases)would not be seen as a multiple system,because,contrary to many exoplanetary systems,the planets are too far from the Sun and the inclinations of their orbits with respect to the ecliptic plane are too high.Primary transit synthetic spectra of solar system planets are used to discuss the relative merits of transmission and direct emission spectroscopy for probing exoplanetary atmospheres.展开更多
The Mare Moscoviense is an astonishing rare flatland multi-ring basin and one of the recognizable mare regions on the Moon's farside.The mineralogical,chronological,topographical and morphological studies of the m...The Mare Moscoviense is an astonishing rare flatland multi-ring basin and one of the recognizable mare regions on the Moon's farside.The mineralogical,chronological,topographical and morphological studies of the maria surface of the Moon provide a primary understanding of the origin and evolution of the mare provinces.In this study,the Chandrayaan-1 M^(3)data have been employed to prepare optical maturity index,FeO and TiO^(2)concentration,and standard band ratio map to detect the mafic indexes like olivine and pyroxene minerals.The crater size frequency distribution method has been applied to LROC WAC data to obtain the absolute model ages of the Moscoviense basin.The four geological unit ages were observed as 3.57 Ga(U-2),3.65 Ga(U-1),3.8 Ga(U-3)and 3.92 Ga(U-4),which could have been formed between the Imbrian and Nectarian epochs.The M^(3)imaging and reflectance spectral parameters were used to reveal the minerals like pyroxene,olivine,ilmenite,plagioclase,orthopyroxene-olivine-spinel lithology,and olivine-pyroxene mixtures present in the gabbroic basalt,anorthositic and massive ilmenite rocks,and validated with the existing database.The results show that the Moscoviense basin is dominated by intermediate TiO^(2)basalts that derived from olivine-ilmenite-pyroxene cumulate depths ranging from 200 to 500 km between 3.5 Ga and 3.6 Ga.展开更多
The early lunar mantle overturn,associated with the sinking of the dense ilmenite-bearing cumulate(IBC)crystallized at the shallow lunar mantle,provides satisfactory explanations for the origination of high-Ti basalt,...The early lunar mantle overturn,associated with the sinking of the dense ilmenite-bearing cumulate(IBC)crystallized at the shallow lunar mantle,provides satisfactory explanations for the origination of high-Ti basalt,the abnormally strong magnetic field between~3.9 and~3.6 Ga and the low-viscosity zone in the deep lunar mantle,but still poses a debate regarding the initial state of IBC in the early lunar mantle.If the sinking of IBC initiated before the end of lunar magma ocean crystallization,the solidified IBC can acquire a greater thickness and a higher initial velocity at the IBC-mantle boundary.The variation of initial velocity can affect the strain rate of IBC and,correspondingly,the dislocation creep components at the shallow lunar mantle.In this work,we analyze the effects of initial velocity on the dynamics of early lunar mantle by using the theory of Rayleigh-Taylor instability.To couple the effects of diffusion creep and dislocation creep for all major minerals in the lunar mantle,we exploit an improved Minimized Power Geometric(IMPG)model and isostress mixing model to characterize the upper limit and lower limit for the viscosity of the lunar mantle comprising four major minerals,i.e.olivine,orthopyroxene,clinopyroxene and ilmenite.The modeling results suggest that a high initial velocity,in any case,can shorten the onset time,tending to promote the early lunar mantle overturn even in a rheologically-strong lunar mantle.The effect of initial velocity on the overturn wavelength shows a strong dependence on the rheological mixing model.For the isostress mixing model,the increase of initial velocity tends to elongate the overturn wavelength.For the IMPG mixing model,the overturn wavelength is insensitive to the variation of initial velocity.As the actual lunar mantle rheology sandwiches between the rheologies predicted by isostress mixing model and IMPG model,it can be anticipated that the increase of initial velocity tends to elongate the overturn wavelength.In consideration of the importance of the initial velocity on the dynamics of early lunar mantle,future investigations should focus on the dynamics of the solid IBC in the solidifying lunar magma ocean.展开更多
The technique of X-ray fluorescence remote sensing plays a significant role in research related to the chemical compositions of the Moon. Here we describe the data analysis method for China＇s Chang＇E-2 X-ray spectro...The technique of X-ray fluorescence remote sensing plays a significant role in research related to the chemical compositions of the Moon. Here we describe the data analysis method for China＇s Chang＇E-2 X-ray spectrometer in detail and present the preliminary results about the first global Mg/Si and Al/Si maps of the lunar surface. Our results show that the distributions of Mg/Si and Al/Si correlate well with terrains on the Moon. The higher Mg/Si ratio corresponds to the mare regions while the lower value corresponds to the highland terrains. The map of the Al/Si ratio shows a reversed distribution compared with the map of the Mg/Si ratio.展开更多
基金funded by Paris Observatory and the Centre National de la Recherche Scientifique。
文摘The purpose of this paper is to address the question:Using our knowledge of infrared planetary spectroscopy,what can we learn about the atmospheres of exoplanets?In a first part,a simplified classification of exoplanets,assuming thermochemical equilibrium,is presented,based on their masses and their equilibrium temperatures,in order to propose some possible estimations about their atmospheric composition.In the second part,infrared spectra of planets are discussed,in order to see what lessons can be drawn for exoplanetary spectroscopy.In the last part,we consider the solar system as it would appear from a star located in the ecliptic plane.It first appears that the solar system(except in a few specific cases)would not be seen as a multiple system,because,contrary to many exoplanetary systems,the planets are too far from the Sun and the inclinations of their orbits with respect to the ecliptic plane are too high.Primary transit synthetic spectra of solar system planets are used to discuss the relative merits of transmission and direct emission spectroscopy for probing exoplanetary atmospheres.
基金the Indian Space Research Organization,Bangalore,for funding under the Ch-1 AO Research Project(ISRO/SSPO/CH-1/2016–2019)to carry out this research work。
文摘The Mare Moscoviense is an astonishing rare flatland multi-ring basin and one of the recognizable mare regions on the Moon's farside.The mineralogical,chronological,topographical and morphological studies of the maria surface of the Moon provide a primary understanding of the origin and evolution of the mare provinces.In this study,the Chandrayaan-1 M^(3)data have been employed to prepare optical maturity index,FeO and TiO^(2)concentration,and standard band ratio map to detect the mafic indexes like olivine and pyroxene minerals.The crater size frequency distribution method has been applied to LROC WAC data to obtain the absolute model ages of the Moscoviense basin.The four geological unit ages were observed as 3.57 Ga(U-2),3.65 Ga(U-1),3.8 Ga(U-3)and 3.92 Ga(U-4),which could have been formed between the Imbrian and Nectarian epochs.The M^(3)imaging and reflectance spectral parameters were used to reveal the minerals like pyroxene,olivine,ilmenite,plagioclase,orthopyroxene-olivine-spinel lithology,and olivine-pyroxene mixtures present in the gabbroic basalt,anorthositic and massive ilmenite rocks,and validated with the existing database.The results show that the Moscoviense basin is dominated by intermediate TiO^(2)basalts that derived from olivine-ilmenite-pyroxene cumulate depths ranging from 200 to 500 km between 3.5 Ga and 3.6 Ga.
基金the Fund for Development of Science and Technology of Macao SAR(121/2017/A3)。
文摘The early lunar mantle overturn,associated with the sinking of the dense ilmenite-bearing cumulate(IBC)crystallized at the shallow lunar mantle,provides satisfactory explanations for the origination of high-Ti basalt,the abnormally strong magnetic field between~3.9 and~3.6 Ga and the low-viscosity zone in the deep lunar mantle,but still poses a debate regarding the initial state of IBC in the early lunar mantle.If the sinking of IBC initiated before the end of lunar magma ocean crystallization,the solidified IBC can acquire a greater thickness and a higher initial velocity at the IBC-mantle boundary.The variation of initial velocity can affect the strain rate of IBC and,correspondingly,the dislocation creep components at the shallow lunar mantle.In this work,we analyze the effects of initial velocity on the dynamics of early lunar mantle by using the theory of Rayleigh-Taylor instability.To couple the effects of diffusion creep and dislocation creep for all major minerals in the lunar mantle,we exploit an improved Minimized Power Geometric(IMPG)model and isostress mixing model to characterize the upper limit and lower limit for the viscosity of the lunar mantle comprising four major minerals,i.e.olivine,orthopyroxene,clinopyroxene and ilmenite.The modeling results suggest that a high initial velocity,in any case,can shorten the onset time,tending to promote the early lunar mantle overturn even in a rheologically-strong lunar mantle.The effect of initial velocity on the overturn wavelength shows a strong dependence on the rheological mixing model.For the isostress mixing model,the increase of initial velocity tends to elongate the overturn wavelength.For the IMPG mixing model,the overturn wavelength is insensitive to the variation of initial velocity.As the actual lunar mantle rheology sandwiches between the rheologies predicted by isostress mixing model and IMPG model,it can be anticipated that the increase of initial velocity tends to elongate the overturn wavelength.In consideration of the importance of the initial velocity on the dynamics of early lunar mantle,future investigations should focus on the dynamics of the solid IBC in the solidifying lunar magma ocean.
基金supported by the Science and Technology Development Fund of Macao (Grant Nos.068/2011/A,048/2012/A2,039/2013/A2,091/2013/A3 and 020/2014/A1)by the Key Research Program of the Chinese Academy of Sciences (Grant No.KGZD-EW603)
文摘The technique of X-ray fluorescence remote sensing plays a significant role in research related to the chemical compositions of the Moon. Here we describe the data analysis method for China＇s Chang＇E-2 X-ray spectrometer in detail and present the preliminary results about the first global Mg/Si and Al/Si maps of the lunar surface. Our results show that the distributions of Mg/Si and Al/Si correlate well with terrains on the Moon. The higher Mg/Si ratio corresponds to the mare regions while the lower value corresponds to the highland terrains. The map of the Al/Si ratio shows a reversed distribution compared with the map of the Mg/Si ratio.
