We present systematic identifications of supergiants in M31/M33 based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)spectroscopic survey.Radial velocities of nearly 5000 photometrically selec...We present systematic identifications of supergiants in M31/M33 based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)spectroscopic survey.Radial velocities of nearly 5000 photometrically selected M31/M33 supergiant candidates have been properly derived from the qualified spectra released in LAMOST DR10.By comparing their radial velocities with those predicted from the rotation curve of M31,as well as utilizing Gaia astrometric measurements to exclude foreground contaminations,199 supergiant members in M31,including 168“Rank1”and 31“Rank2,”have been successfully identified.This sample contains 62 blue supergiants(BSGs,all“Rank1”),134 yellow supergiants(YSGs,103“Rank1”and 31“Rank2”)and three red supergiants(RSGs,all“Rank1”).For M33,we identify 84 supergiant members(56“Rank1”and 28“Rank2”),which include 28 BSGs(all“Rank1”),53 YSGs(25“Rank1”and 28“Rank2”)and three RSGs(all“Rank1”).So far,this is one of the largest supergiant samples of M31/M33 with full optical wavelength coverage(3700<λ<9100Å).This sample is valuable for understanding star formation and stellar evolution under different environments.展开更多
Sodium overabundance in yellow supergiants has stumped people for more than 20 years. The purpose of this paper is to explore this problem from the perspective of nuclear physics. We investigate carefully the CNO and ...Sodium overabundance in yellow supergiants has stumped people for more than 20 years. The purpose of this paper is to explore this problem from the perspective of nuclear physics. We investigate carefully the CNO and NeNa cycles that are responsible for sodium production. We investigate some key reactions in the appropriate network. We show whether and how the sodium output can be affected by the rate uncertainties in these reactions. In this way, we evaluate if a reaction is important enough to deserve a better determination of its rate in terrestrial laboratories.展开更多
Since the first discovery of gold deposits on the northeastern margin of the Jiaolai Basin in Shandong Province at the end of the 20^(th) century,seven medium-sized to large/super-large gold deposits have been identif...Since the first discovery of gold deposits on the northeastern margin of the Jiaolai Basin in Shandong Province at the end of the 20^(th) century,seven medium-sized to large/super-large gold deposits have been identified in this region,with cumulative proven gold resources of 223 t.This study reviewed the metallogenic and geochemical characteristics of various gold deposits in this region,examined the sources of their ore-forming fluids and materials,as well as their gold metallogenic epochs and processes,and developed a gold metallogenic model.The gold deposits in this region are governed by both dense fractures and detachment structural systems along basin margins,primarily categorized into the altered rock type and the pyrite-bearing carbonate vein type.The latter type,a recently discovered mineralization type in the Jiaodong Peninsula,enjoys high gold grade,a large scale,and high gold mineral fineness,suggesting considerable prospecting potential.Both types of gold deposits show metallogenic epochs ranging from 116 Ma to 119 Ma.Their ore-forming fluids are identified as a CO_(2)-NaCl-H_(2)O fluid system characterized by moderate to low temperatures,moderate to low salinity,and low density,with the pyrite-bearing carbonate vein-type gold deposits manifesting slightly higher salinity.The C-H-O,S,and Pb isotopes of hydrothermal minerals reveal that the ore-forming fluids and materials are characteristic of crust-mantle mixing.Specifically,they were derived from mantle fluids in the early stages,mixed with stratum water and meteoric water in the later stages for mineralization.The gold metallogenic process is identified as follows:During the Early Cretaceous,the subduction of the Pacific Plate and the destruction of the North China Craton led to asthenospheric upwelling.The resulting fluids,after metasomatizing the enriched mantle,differentiated and evolved into C-H-O ore-bearing fluids,which were then mixed with crustal fluids.The mixed fluids migrated to the shallow crust,where they mingled with stratum water and meteoric water.Then,the fluids underwent unloading and final mineralization in detachment fault tectonic systems on basin margins.Due to differences in mixed crustal materials or the surrounding rocks involved in water-rock interactions,altered rock-and pyrite-bearing carbonate vein-type gold deposits were formed in acidic and alkaline fluid environments,respectively.展开更多
We have investigated the relation between the orbital period P<SUB>orb</SUB> and the spin period P<SUB>s</SUB> of neutron stars in OB/X-ray binaries. By simulating the time-development of the m...We have investigated the relation between the orbital period P<SUB>orb</SUB> and the spin period P<SUB>s</SUB> of neutron stars in OB/X-ray binaries. By simulating the time-development of the mass loss rate and radius expansion of a 20M<SUB>☉</SUB> donor star, we have calculated the detailed spin evolution of the neutron star before steady wind accretion occurs (that is, when the break spin period is reached), or when the OB star begins evolving off the main sequence or has filled its Roche lobe. Our results are compatible with the observations of OB/X-ray binaries. We find that in relatively narrow systems with orbital periods less than tens of days, neutron stars with initial magnetic field B<SUB>0</SUB> stronger than about 3×10<SUP>12</SUP> G can reach the break spin period to allow steady wind accretion in the main sequence time, whereas neutron stars with B<SUB>0</SUB> < 3×10<SUP>12</SUP> G and/or in wide systems would still be in one of the pulsar, rapid rotator or propeller phases when the companion evolves off the main sequence or fills its Roche lobe. Our results may help understand the various characteristics of the observed OB/neutron star binaries along with their distributions in the P<SUB>s</SUB>-P<SUB>orb</SUB> diagram.展开更多
In this paper, we investigate the problem of supersonic convection caused by the application of the usual Mixing Length Theory (MLT), and give a modification to the original expression of the MLT. In the case of the u...In this paper, we investigate the problem of supersonic convection caused by the application of the usual Mixing Length Theory (MLT), and give a modification to the original expression of the MLT. In the case of the usual MLT, a zone of supersonic convection exists when the stellar model goes into yellow-red supergiant phase. When the modification is applied, the models of late type supergiants possess shallower convective envelopes for a given temperature compared with the normal formalism of the MLT. Therefore the stellar models made with our new formalism move to lower effective temperature by 100-400 K depending on the luminosity of the star. Such a modification does not affect the convective envelope structure of lower luminosity late type stars, as both expressions of the MLT give the same result. In these stars.展开更多
Magnetars form a special population of neutron stars with strong magnetic fields and long spin periods. About 30 magnetars and magnetar candidates known currently are probably isolated, but the possibility that magnet...Magnetars form a special population of neutron stars with strong magnetic fields and long spin periods. About 30 magnetars and magnetar candidates known currently are probably isolated, but the possibility that magnetars are in binaries has not been excluded. In this work, we perform spin evolution of neutron stars with different magnetic fields in wind-fed high-mass X-ray binaries and compare the spin period distribution with observations, aiming to find magnetars in binaries. Our simulation shows that some of the neutron stars, which have long spin periods or are in widely-separated systems, need strong magnetic fields to explain their spin evolution. This implies that there are probably magnetars in high-mass X-ray binaries. Moreover, this can further provide a theoretical basis for some unclear astronomical phenomena, such as the possible origin of periodic fast radio bursts from magnetars in binary systems.展开更多
Fast Blue Optical Transients(FBOTs)are luminous transients with fast evolving(typically t;<12 days)light curve and blue color(usually-0.2>g-r>-0.3)that cannot be explained by a supernova-like explosion.We pro...Fast Blue Optical Transients(FBOTs)are luminous transients with fast evolving(typically t;<12 days)light curve and blue color(usually-0.2>g-r>-0.3)that cannot be explained by a supernova-like explosion.We propose a radiative diffusion in a time-dependent outflow model to interpret such special transients.In this model,we assume that a central engine ejects continuous outflow during a few days.We consider the ejection of the outflow to be time-dependent.The outflow is optically thick initially and photons are frozen in it.As the outflow expands over time,photons gradually escape,and our work is to model such an evolution.Numerical and analytical calculations are considered separately,and the results are consistent.We apply the model to three typical FBOTs:PS1-10 bjp,ZTF18 abukavn,and ATLAS 19 dqr.The modeling finds the total mass of the outflow(~1-5 M;),and the total time of the ejection(~a few days)for them,leading us to speculate that they may be the result of the collapse of massive stars.展开更多
The Dayin’gezhuang gold deposit is located in the central part of the Zhaoping Fault metallogenic belt in the Jiaodong gold province-the world’s third-largest gold metallogenic area.It is a typical successful case o...The Dayin’gezhuang gold deposit is located in the central part of the Zhaoping Fault metallogenic belt in the Jiaodong gold province-the world’s third-largest gold metallogenic area.It is a typical successful case of prospecting at a depth of 500-2000 m in recent years,with cumulative proven gold resources exceeding 180 t.The main orebodies(No.1 and No.2 orebody)generally have a pitch direction of NNE and a plunge direction of NEE.As the ore-controlling fault,the Zhaoping Fault is a shovel-shaped stepped fault,with its dip angle presenting stepped high-to-low transitions at the elevation of -2000-0 m.The gold mineralization enrichment area is mainly distributed in the step parts where the fault plane changes from steeply to gently,forming a stepped metallogenic pattern from shallow to deep.It can be concluded from previous studies that the gold mineralization of the Dayin’gezhuang gold deposit occurred at about 120 Ma.The ore-forming fluids were H_(2)O-CO_(2)-NaCl-type hydrothermal solutions with a medium-low temperature and medium-low salinity.The H-O isotopic characteristics indicate that the fluids in the early ore-forming stage were possibly magmatic water or mantle water and that meteoric water gradually entered the ore-forming fluids in the late ore-forming stage.The S and Pb isotopes indicate that the ore-forming materials mainly originate from the lower crust and contain a small quantity of mantle-derived components.The comprehensive analysis shows that the Dayin’gezhuang gold deposit was formed by thermal uplifting-extensional tectonism.The strong crust-mantle interactions,large-scale magmatism,and the material exchange arising from the transformation from adakitic granites to arc granites and from the ancient lower crust to the juvenile lower crust during the Early Cretaceous provided abundant fluids and material sources for mineralization.Moreover,the detachment faults formed by the rapid magmatic uplift and the extensional tectonism created favorable temperature and pressure conditions and space for fluid accumulation and gold precipitation and mineralization.展开更多
The Jiama porphyry copper deposit in Xizang is one of the proven supergiant copper deposits in the Qinghai-Tibet Plateau at present,with the reserves of geological resources equivalent to nearly 20×10^(6)t.Howeve...The Jiama porphyry copper deposit in Xizang is one of the proven supergiant copper deposits in the Qinghai-Tibet Plateau at present,with the reserves of geological resources equivalent to nearly 20×10^(6)t.However,it features wavy and steep terrain,leading to extremely difficult field operation and heavy interference.This study attempts to determine the effects of the tensor controlled-source audiomagnetotellurics(CSAMT)with high-power orthogonal signal sources(also referred to as the high-power tensor CSAMT)when it is applied to the deep geophysical exploration in plateaus with complex terrain and mining areas with strong interference.The test results show that the high current provided by the highpower tensor CSAMT not only greatly improved the signal-to-noise ratio but also guaranteed that effective signals were received in the case of a long transmitter-receiver distance.Meanwhile,the tensor data better described the anisotropy of deep geologic bodies.In addition,the tests also show that when the transmitting current reaches 60 A,it is still guaranteed that strong enough signals can be received in the case of the transmitter-receiver distance of about 25 km,sounding curves show no near field effect,and effective exploration depth can reach 3 km.The 2D inversion results are roughly consistent with drilling results,indicating that the high-power tensor CSAMT can be used to achieve nearly actual characteristics of underground electrical structures.Therefore,this method has great potential for application in deep geophysical exploration in plateaus and mining areas with complex terrain and strong interference,respectively.This study not only serves as important guidance on the prospecting in the Qinghai-Tibet Plateau but also can be used as positive references for deep mineral exploration in other areas.展开更多
By the end of 2020,83 silver deposits(or ore occurrences),including four super-large-scale deposits,nine large-scale deposits,33 medium-scale deposits and 37 small-scale deposits or ore occurrences,have been proved.Th...By the end of 2020,83 silver deposits(or ore occurrences),including four super-large-scale deposits,nine large-scale deposits,33 medium-scale deposits and 37 small-scale deposits or ore occurrences,have been proved.The amount of silver metal exceeds 86000 t with average grade of 100 g/t,which makes Daxing’anling region one of the the most important silver ore belt in China.However,the metallogenic characteristics and metallogenesis need to be clarified.The silver deposits in the study area are classified into three main types,which are magmatic hydrothermal vein type,continental volcano-subvolcanic type and skarn type,respectively.The supergiant deposits include the Shuangjianzishan deposit(silver metal amount of 15214 t with average grade of 138 g/t),the Baiyinchagandongshan deposit(silver metal amount of 9446 t with average grade of 187 g/t),the Huaobaote deposit(silver metal amount of 6852 t with average grade of 170 g/t),and the Fuxingtun deposit(silver metal amount of 5240 t with average grade of 196 g/t).The silver deposits are mainly distributed in the central and south of the Daxing’anling area,and mainly formed in the Yanshanian period.The silver polymetallic deposits in the Daxinganling area are significantly controlled by regional faults and the junction zone of volcanic rock basins and their margins.The north-east trending deep faults are the most important ore-controlling structures in this area.The distribution of silver polymetallic deposits along the main faults is obvious,and the intersection area of multiple groups of faults often form important mine catchments.The Permian is the most important ore-bearing formation in this area,but some important silver polymetallic deposits occur in Mesozoic volcanic basins or pre-Mesozoic strata.The magmatic rocks related to mineralization are mainly intermediate acidic or acidic intrusions,intermediate acidic lavas,pyroclastic rocks,and small intrusions of ultra-shallow or shallow facies of the Yanshanian Period.The mineralization element combination is mainly determined by the elemental geochemical background of surrounding rocks or source layers.In addition,the type of deposit,the distance from the mineralization center,and the degree of differentiation of ore-forming rock mass are also important influence factors.The article analyzes the prospecting prospects of each silver deposit type in the study area,discusses the relationship between mineralization center and deep prospecting,and proposes that porphyry silver deposits should be paid attention to.In the prospecting and exploration of silver deposits,comprehensive evaluation and multi-target prospecting need to be strengthened because silver can coexist or be associated with a variety of metals.展开更多
The Xikuangshan antimony deposit in central Hunan, South China, is the largest antimony deposit ever known in the world. The ore bodies are strictly confined to the footwalls of mafor high-angle normal faults which tr...The Xikuangshan antimony deposit in central Hunan, South China, is the largest antimony deposit ever known in the world. The ore bodies are strictly confined to the footwalls of mafor high-angle normal faults which transect the inclined folds in the flank;away from the fault planes,both the homogenization temperatures of inclusions in gangue minerals and the intensity of antimony mineralization decrease.These characteristics strongly demonstrate that the faults are used as the conduit for the metal-bearing fluid in mineralization.The normal faults,striking the NE to NNE,are interpreted to be generated by the postmgenic extension in the time from Cretaceous to Paleogene.Crustal or lithospheric thinning, directly resulting from regional extension inevitably increase the geothermal gradient, Which is likely to cause large-scale convection of underground water that may leach out and transport valuablemetals such as Sb from source rocks.Focussed discharge along the fault zones contributes to the formation of the supergiant antimony deposit in Xikuangshan under the appropriate sedimentary barrier.展开更多
Variations of the Ha line in the spectra of the star HD14134 are investigated using ob- servations carried out in 2013-2014 and in 2016 with the 2-m telescope at Shamakhy Astrophysical Observatory. In the spectra of t...Variations of the Ha line in the spectra of the star HD14134 are investigated using ob- servations carried out in 2013-2014 and in 2016 with the 2-m telescope at Shamakhy Astrophysical Observatory. In the spectra of this star, the absorption and emission components of Hα are found to disappear and an inverse P Cyg profile of Ha is seen on some observational epochs. Our observations showed that when the Ha line disappeared or an inversion of the P-Cyg-type profile is observed in the spectra, the Hβ line is redshifted. When these events appeared, no synchronous variabilities were ob- served in the spectral parameters of other spectral lines formed in deeper atmospheric layers. In addition, the structures of Ha, CII （6578.05A, 6582.88A）, Sill （6347.1 A, 6371.36A） and Hβ lines are variable on a timescale of hours, but we did not detect significant variations in the other photospheric lines, as well as in the HeI （5875.72A） line. It is suggested that observational evidence for the non-stationary atmosphere of HD 14134 can be associated in part with non-spherical stellar wind.展开更多
In recent years,the Sichuan Basin has been the most potential hydrocarbon-bearing basin in China thanks to the great exploration and development breakthroughs of deep large integral carbonate gas reservoirs and shale ...In recent years,the Sichuan Basin has been the most potential hydrocarbon-bearing basin in China thanks to the great exploration and development breakthroughs of deep large integral carbonate gas reservoirs and shale gas in this basin.The Anyue Gas Field located in central Sichuan Basin is not only the largest carbonate gas reservoir,but the most important supergiant gas field discovered in China in recent years.However,it faces a series of major difficulties,e.g.,low reservoir porosity,low permeability,low gas well productivity,thin and vertically and laterally disperse gas layer,strong heterogeneity,quite low structural amplitude and complicated gasewater relationship,which bring great challenges to the rapid conversion of natural gas reserves to production.In this regard,technical researches have been carried out continuously.As a result,many key technologies have been innovatively integrated and great breakthroughs have been realized in many aspects.First,fine development technologies for supergiant,ancient and complex carbonate gas reservoirs are developed innovatively,“transparent gas reservoir”is constructed and the technologies for cultivating high-yield wells are established.By virtue of these technologies,all development wells in the gas reservoir of Lower Cambrian Longwangmiao Formation reach the target of high yield and the single-well gas production rate of the gas reservoir of Lower Sinian Dengying Formation is increased significantly,which provides support for the long-term high production and stable production of Anyue Gas Field.Second,good and fast construction technologies for large-scale gas fields are innovatively integrated.Based on this,the safety of gas wells is under control in the whole life cycle,quality engineering is built up efficiently within 3 years,green mining areas are forged and large-scale safe and clean gas fields are built up efficiently.Third,intelligent control technologies for the development of supergiant gas fields are innovatively integrated.By means of these technologies,internet of everything,depth perception and automatic production are realized.The intelligent technologies of new generation are fused,including AR,VR,robot and unmanned aerial vehicle(UAV).A new intelligent management mode for gas field development is set up,and an intelligent gas field is built up.Fourth,optimization technologies for the overall development of supergiant gas fields are innovatively development,so as to improve the development effects of strong-heterogeneity gas reservoirs and ensure the long-term stable production of supergiant water-bearing gas reservoirs.The research results can be used as reference for the efficient development of similar domestic and foreign gas fields.展开更多
Stars with initial masses in the range of 8-25 solar masses are thought to end their lives as hydrogen-rich supernovae(SNeⅡ).Based on the pre-explosion images of Hubble space telescope(HST)and Spitzer space telescope...Stars with initial masses in the range of 8-25 solar masses are thought to end their lives as hydrogen-rich supernovae(SNeⅡ).Based on the pre-explosion images of Hubble space telescope(HST)and Spitzer space telescope,we place tight constraints on the progenitor candidate of type IIP SN 2023ixf in Messier 101.Fitting of the spectral energy distribution(SED)of its progenitor with dusty stellar spectral models results in an estimation of the effective temperature as 3091+422-258K.The luminosity is estimated as lg(L/L⊙)~4.83,consistent with a red supergiant(RSG)star with an initial mass of 12-1+2M⊙.The derived mass loss rate(6×10^(-6)-9×10^(-6)M⊙yr^(-1))is much lower than that inferred from the flash spectroscopy of the SN,suggesting that the progenitor experienced a sudden increase in mass loss when approaching the final explosion.In the infrared bands,significant deviation from the range of regular RSGs in the color-magnitude diagram and period-luminosity space of the progenitor star indicates enhanced mass loss and dust formation.Combined with new evidence of polarization at the early phases of SN 2023ixf,such a violent mass loss is likely a result of binary interaction.展开更多
基金funded by the National Natural Science Foundation of China(NSFC,grant Nos.12090040,12090044,12133001,and 12422303)Beijing Natural Science Foundation(no.1242016)+2 种基金the science research grants from the China Manned Space Projectsupported by the Talents Program(24CE-YS-08)the Popular Science Project(24CD012)of the Beijing Academy of Science and Technology.
文摘We present systematic identifications of supergiants in M31/M33 based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)spectroscopic survey.Radial velocities of nearly 5000 photometrically selected M31/M33 supergiant candidates have been properly derived from the qualified spectra released in LAMOST DR10.By comparing their radial velocities with those predicted from the rotation curve of M31,as well as utilizing Gaia astrometric measurements to exclude foreground contaminations,199 supergiant members in M31,including 168“Rank1”and 31“Rank2,”have been successfully identified.This sample contains 62 blue supergiants(BSGs,all“Rank1”),134 yellow supergiants(YSGs,103“Rank1”and 31“Rank2”)and three red supergiants(RSGs,all“Rank1”).For M33,we identify 84 supergiant members(56“Rank1”and 28“Rank2”),which include 28 BSGs(all“Rank1”),53 YSGs(25“Rank1”and 28“Rank2”)and three RSGs(all“Rank1”).So far,this is one of the largest supergiant samples of M31/M33 with full optical wavelength coverage(3700<λ<9100Å).This sample is valuable for understanding star formation and stellar evolution under different environments.
基金Supported by the National Natural Science Foundation of China (NSFC,Nos.10173005 and 10773005).
文摘Sodium overabundance in yellow supergiants has stumped people for more than 20 years. The purpose of this paper is to explore this problem from the perspective of nuclear physics. We investigate carefully the CNO and NeNa cycles that are responsible for sodium production. We investigate some key reactions in the appropriate network. We show whether and how the sodium output can be affected by the rate uncertainties in these reactions. In this way, we evaluate if a reaction is important enough to deserve a better determination of its rate in terrestrial laboratories.
基金supported by the Program of the National Natural Science Foundation of China(Nos.41973048,U2006201)the Open Project of State Key Laboratory of Geological Processes and Mineral Resources(No.GPMR202203)+1 种基金the Key R&D Program of Shandong Province(No.2023CXGC011001),the Taishan Scholars.Program(tstp20240847)the Open Project of Shandong Engineering Research Center of Application and Development of Big Data for Deep Gold Exploration(No.SDK202207)。
文摘Since the first discovery of gold deposits on the northeastern margin of the Jiaolai Basin in Shandong Province at the end of the 20^(th) century,seven medium-sized to large/super-large gold deposits have been identified in this region,with cumulative proven gold resources of 223 t.This study reviewed the metallogenic and geochemical characteristics of various gold deposits in this region,examined the sources of their ore-forming fluids and materials,as well as their gold metallogenic epochs and processes,and developed a gold metallogenic model.The gold deposits in this region are governed by both dense fractures and detachment structural systems along basin margins,primarily categorized into the altered rock type and the pyrite-bearing carbonate vein type.The latter type,a recently discovered mineralization type in the Jiaodong Peninsula,enjoys high gold grade,a large scale,and high gold mineral fineness,suggesting considerable prospecting potential.Both types of gold deposits show metallogenic epochs ranging from 116 Ma to 119 Ma.Their ore-forming fluids are identified as a CO_(2)-NaCl-H_(2)O fluid system characterized by moderate to low temperatures,moderate to low salinity,and low density,with the pyrite-bearing carbonate vein-type gold deposits manifesting slightly higher salinity.The C-H-O,S,and Pb isotopes of hydrothermal minerals reveal that the ore-forming fluids and materials are characteristic of crust-mantle mixing.Specifically,they were derived from mantle fluids in the early stages,mixed with stratum water and meteoric water in the later stages for mineralization.The gold metallogenic process is identified as follows:During the Early Cretaceous,the subduction of the Pacific Plate and the destruction of the North China Craton led to asthenospheric upwelling.The resulting fluids,after metasomatizing the enriched mantle,differentiated and evolved into C-H-O ore-bearing fluids,which were then mixed with crustal fluids.The mixed fluids migrated to the shallow crust,where they mingled with stratum water and meteoric water.Then,the fluids underwent unloading and final mineralization in detachment fault tectonic systems on basin margins.Due to differences in mixed crustal materials or the surrounding rocks involved in water-rock interactions,altered rock-and pyrite-bearing carbonate vein-type gold deposits were formed in acidic and alkaline fluid environments,respectively.
基金Supported by the National Natural Science Foundation of China.
文摘We have investigated the relation between the orbital period P<SUB>orb</SUB> and the spin period P<SUB>s</SUB> of neutron stars in OB/X-ray binaries. By simulating the time-development of the mass loss rate and radius expansion of a 20M<SUB>☉</SUB> donor star, we have calculated the detailed spin evolution of the neutron star before steady wind accretion occurs (that is, when the break spin period is reached), or when the OB star begins evolving off the main sequence or has filled its Roche lobe. Our results are compatible with the observations of OB/X-ray binaries. We find that in relatively narrow systems with orbital periods less than tens of days, neutron stars with initial magnetic field B<SUB>0</SUB> stronger than about 3×10<SUP>12</SUP> G can reach the break spin period to allow steady wind accretion in the main sequence time, whereas neutron stars with B<SUB>0</SUB> < 3×10<SUP>12</SUP> G and/or in wide systems would still be in one of the pulsar, rapid rotator or propeller phases when the companion evolves off the main sequence or fills its Roche lobe. Our results may help understand the various characteristics of the observed OB/neutron star binaries along with their distributions in the P<SUB>s</SUB>-P<SUB>orb</SUB> diagram.
基金the NationalNatural Science Foundation of China (NSFC) this work is also partly supported by the Ministryof Science and Tec
文摘In this paper, we investigate the problem of supersonic convection caused by the application of the usual Mixing Length Theory (MLT), and give a modification to the original expression of the MLT. In the case of the usual MLT, a zone of supersonic convection exists when the stellar model goes into yellow-red supergiant phase. When the modification is applied, the models of late type supergiants possess shallower convective envelopes for a given temperature compared with the normal formalism of the MLT. Therefore the stellar models made with our new formalism move to lower effective temperature by 100-400 K depending on the luminosity of the star. Such a modification does not affect the convective envelope structure of lower luminosity late type stars, as both expressions of the MLT give the same result. In these stars.
基金Supported by the National Natural Science Foundation of China。
文摘Magnetars form a special population of neutron stars with strong magnetic fields and long spin periods. About 30 magnetars and magnetar candidates known currently are probably isolated, but the possibility that magnetars are in binaries has not been excluded. In this work, we perform spin evolution of neutron stars with different magnetic fields in wind-fed high-mass X-ray binaries and compare the spin period distribution with observations, aiming to find magnetars in binaries. Our simulation shows that some of the neutron stars, which have long spin periods or are in widely-separated systems, need strong magnetic fields to explain their spin evolution. This implies that there are probably magnetars in high-mass X-ray binaries. Moreover, this can further provide a theoretical basis for some unclear astronomical phenomena, such as the possible origin of periodic fast radio bursts from magnetars in binary systems.
基金supported by the China Manned Spaced Project(CMS-CSST-2021-B11)National Natural Science Foundation of China(12073091)Guangdong Basic and Applied Basic Research Foundation(2019A1515011119)。
文摘Fast Blue Optical Transients(FBOTs)are luminous transients with fast evolving(typically t;<12 days)light curve and blue color(usually-0.2>g-r>-0.3)that cannot be explained by a supernova-like explosion.We propose a radiative diffusion in a time-dependent outflow model to interpret such special transients.In this model,we assume that a central engine ejects continuous outflow during a few days.We consider the ejection of the outflow to be time-dependent.The outflow is optically thick initially and photons are frozen in it.As the outflow expands over time,photons gradually escape,and our work is to model such an evolution.Numerical and analytical calculations are considered separately,and the results are consistent.We apply the model to three typical FBOTs:PS1-10 bjp,ZTF18 abukavn,and ATLAS 19 dqr.The modeling finds the total mass of the outflow(~1-5 M;),and the total time of the ejection(~a few days)for them,leading us to speculate that they may be the result of the collapse of massive stars.
基金financially supported by the NSFC-Shandong Joint Fund Program entitled“Control Mechanisms of Faults on Deep Gold Deposits in Jiaodong Peninsula”(Grant No.U2006201)Science and Technology Project of Shandong Bureau of Geology and Mineral Exploration and Development entitled“Fault system and its relationship with gold mineralization,northwestern Jiaodong Peninsula”(Grant No.KY202208)Open Fund of Big Data Application and Development Engineering Laboratory for Deep Gold Exploration in Shandong Province entitled“Ore-forming fluid and ore-forming material source of Jiudian gold deposit,Jiaodong”(Grant No.SDK202211).
文摘The Dayin’gezhuang gold deposit is located in the central part of the Zhaoping Fault metallogenic belt in the Jiaodong gold province-the world’s third-largest gold metallogenic area.It is a typical successful case of prospecting at a depth of 500-2000 m in recent years,with cumulative proven gold resources exceeding 180 t.The main orebodies(No.1 and No.2 orebody)generally have a pitch direction of NNE and a plunge direction of NEE.As the ore-controlling fault,the Zhaoping Fault is a shovel-shaped stepped fault,with its dip angle presenting stepped high-to-low transitions at the elevation of -2000-0 m.The gold mineralization enrichment area is mainly distributed in the step parts where the fault plane changes from steeply to gently,forming a stepped metallogenic pattern from shallow to deep.It can be concluded from previous studies that the gold mineralization of the Dayin’gezhuang gold deposit occurred at about 120 Ma.The ore-forming fluids were H_(2)O-CO_(2)-NaCl-type hydrothermal solutions with a medium-low temperature and medium-low salinity.The H-O isotopic characteristics indicate that the fluids in the early ore-forming stage were possibly magmatic water or mantle water and that meteoric water gradually entered the ore-forming fluids in the late ore-forming stage.The S and Pb isotopes indicate that the ore-forming materials mainly originate from the lower crust and contain a small quantity of mantle-derived components.The comprehensive analysis shows that the Dayin’gezhuang gold deposit was formed by thermal uplifting-extensional tectonism.The strong crust-mantle interactions,large-scale magmatism,and the material exchange arising from the transformation from adakitic granites to arc granites and from the ancient lower crust to the juvenile lower crust during the Early Cretaceous provided abundant fluids and material sources for mineralization.Moreover,the detachment faults formed by the rapid magmatic uplift and the extensional tectonism created favorable temperature and pressure conditions and space for fluid accumulation and gold precipitation and mineralization.
基金supported by the National Key Research and Development Program of China(2018YFC0604102)the project of China Geological Survey(DD20190015)。
文摘The Jiama porphyry copper deposit in Xizang is one of the proven supergiant copper deposits in the Qinghai-Tibet Plateau at present,with the reserves of geological resources equivalent to nearly 20×10^(6)t.However,it features wavy and steep terrain,leading to extremely difficult field operation and heavy interference.This study attempts to determine the effects of the tensor controlled-source audiomagnetotellurics(CSAMT)with high-power orthogonal signal sources(also referred to as the high-power tensor CSAMT)when it is applied to the deep geophysical exploration in plateaus with complex terrain and mining areas with strong interference.The test results show that the high current provided by the highpower tensor CSAMT not only greatly improved the signal-to-noise ratio but also guaranteed that effective signals were received in the case of a long transmitter-receiver distance.Meanwhile,the tensor data better described the anisotropy of deep geologic bodies.In addition,the tests also show that when the transmitting current reaches 60 A,it is still guaranteed that strong enough signals can be received in the case of the transmitter-receiver distance of about 25 km,sounding curves show no near field effect,and effective exploration depth can reach 3 km.The 2D inversion results are roughly consistent with drilling results,indicating that the high-power tensor CSAMT can be used to achieve nearly actual characteristics of underground electrical structures.Therefore,this method has great potential for application in deep geophysical exploration in plateaus and mining areas with complex terrain and strong interference,respectively.This study not only serves as important guidance on the prospecting in the Qinghai-Tibet Plateau but also can be used as positive references for deep mineral exploration in other areas.
基金financially supported by the projects of China Geological Survey(DD20221695,DD20160346 and DD20190379)the Fundamental Research Funds of the Central Public Welfare Scientific Research Institutes(JYYWF20183701 and JYYWF20183704)the Inner Mongolia Geological Exploration Fund Project(2020-YS03).
文摘By the end of 2020,83 silver deposits(or ore occurrences),including four super-large-scale deposits,nine large-scale deposits,33 medium-scale deposits and 37 small-scale deposits or ore occurrences,have been proved.The amount of silver metal exceeds 86000 t with average grade of 100 g/t,which makes Daxing’anling region one of the the most important silver ore belt in China.However,the metallogenic characteristics and metallogenesis need to be clarified.The silver deposits in the study area are classified into three main types,which are magmatic hydrothermal vein type,continental volcano-subvolcanic type and skarn type,respectively.The supergiant deposits include the Shuangjianzishan deposit(silver metal amount of 15214 t with average grade of 138 g/t),the Baiyinchagandongshan deposit(silver metal amount of 9446 t with average grade of 187 g/t),the Huaobaote deposit(silver metal amount of 6852 t with average grade of 170 g/t),and the Fuxingtun deposit(silver metal amount of 5240 t with average grade of 196 g/t).The silver deposits are mainly distributed in the central and south of the Daxing’anling area,and mainly formed in the Yanshanian period.The silver polymetallic deposits in the Daxinganling area are significantly controlled by regional faults and the junction zone of volcanic rock basins and their margins.The north-east trending deep faults are the most important ore-controlling structures in this area.The distribution of silver polymetallic deposits along the main faults is obvious,and the intersection area of multiple groups of faults often form important mine catchments.The Permian is the most important ore-bearing formation in this area,but some important silver polymetallic deposits occur in Mesozoic volcanic basins or pre-Mesozoic strata.The magmatic rocks related to mineralization are mainly intermediate acidic or acidic intrusions,intermediate acidic lavas,pyroclastic rocks,and small intrusions of ultra-shallow or shallow facies of the Yanshanian Period.The mineralization element combination is mainly determined by the elemental geochemical background of surrounding rocks or source layers.In addition,the type of deposit,the distance from the mineralization center,and the degree of differentiation of ore-forming rock mass are also important influence factors.The article analyzes the prospecting prospects of each silver deposit type in the study area,discusses the relationship between mineralization center and deep prospecting,and proposes that porphyry silver deposits should be paid attention to.In the prospecting and exploration of silver deposits,comprehensive evaluation and multi-target prospecting need to be strengthened because silver can coexist or be associated with a variety of metals.
文摘The Xikuangshan antimony deposit in central Hunan, South China, is the largest antimony deposit ever known in the world. The ore bodies are strictly confined to the footwalls of mafor high-angle normal faults which transect the inclined folds in the flank;away from the fault planes,both the homogenization temperatures of inclusions in gangue minerals and the intensity of antimony mineralization decrease.These characteristics strongly demonstrate that the faults are used as the conduit for the metal-bearing fluid in mineralization.The normal faults,striking the NE to NNE,are interpreted to be generated by the postmgenic extension in the time from Cretaceous to Paleogene.Crustal or lithospheric thinning, directly resulting from regional extension inevitably increase the geothermal gradient, Which is likely to cause large-scale convection of underground water that may leach out and transport valuablemetals such as Sb from source rocks.Focussed discharge along the fault zones contributes to the formation of the supergiant antimony deposit in Xikuangshan under the appropriate sedimentary barrier.
基金supported by the scientific program for priority fields of research of the National Academy of Sciences of Azerbaijan
文摘Variations of the Ha line in the spectra of the star HD14134 are investigated using ob- servations carried out in 2013-2014 and in 2016 with the 2-m telescope at Shamakhy Astrophysical Observatory. In the spectra of this star, the absorption and emission components of Hα are found to disappear and an inverse P Cyg profile of Ha is seen on some observational epochs. Our observations showed that when the Ha line disappeared or an inversion of the P-Cyg-type profile is observed in the spectra, the Hβ line is redshifted. When these events appeared, no synchronous variabilities were ob- served in the spectral parameters of other spectral lines formed in deeper atmospheric layers. In addition, the structures of Ha, CII （6578.05A, 6582.88A）, Sill （6347.1 A, 6371.36A） and Hβ lines are variable on a timescale of hours, but we did not detect significant variations in the other photospheric lines, as well as in the HeI （5875.72A） line. It is suggested that observational evidence for the non-stationary atmosphere of HD 14134 can be associated in part with non-spherical stellar wind.
基金supported by the National Major Science and Technology Project“Demonstration Project of Developing Large-Scale Carbonate Gas Field in the Sichuan Basin”(No.:2016ZX05052)PetroChina Major Science and Technology Project“Research and Application of Key Techniques for Put on Production of 30 Billion Cubic Meters of Natural Gas in Southwest Oil and Gas Fields”(No.:2016E-06).
文摘In recent years,the Sichuan Basin has been the most potential hydrocarbon-bearing basin in China thanks to the great exploration and development breakthroughs of deep large integral carbonate gas reservoirs and shale gas in this basin.The Anyue Gas Field located in central Sichuan Basin is not only the largest carbonate gas reservoir,but the most important supergiant gas field discovered in China in recent years.However,it faces a series of major difficulties,e.g.,low reservoir porosity,low permeability,low gas well productivity,thin and vertically and laterally disperse gas layer,strong heterogeneity,quite low structural amplitude and complicated gasewater relationship,which bring great challenges to the rapid conversion of natural gas reserves to production.In this regard,technical researches have been carried out continuously.As a result,many key technologies have been innovatively integrated and great breakthroughs have been realized in many aspects.First,fine development technologies for supergiant,ancient and complex carbonate gas reservoirs are developed innovatively,“transparent gas reservoir”is constructed and the technologies for cultivating high-yield wells are established.By virtue of these technologies,all development wells in the gas reservoir of Lower Cambrian Longwangmiao Formation reach the target of high yield and the single-well gas production rate of the gas reservoir of Lower Sinian Dengying Formation is increased significantly,which provides support for the long-term high production and stable production of Anyue Gas Field.Second,good and fast construction technologies for large-scale gas fields are innovatively integrated.Based on this,the safety of gas wells is under control in the whole life cycle,quality engineering is built up efficiently within 3 years,green mining areas are forged and large-scale safe and clean gas fields are built up efficiently.Third,intelligent control technologies for the development of supergiant gas fields are innovatively integrated.By means of these technologies,internet of everything,depth perception and automatic production are realized.The intelligent technologies of new generation are fused,including AR,VR,robot and unmanned aerial vehicle(UAV).A new intelligent management mode for gas field development is set up,and an intelligent gas field is built up.Fourth,optimization technologies for the overall development of supergiant gas fields are innovatively development,so as to improve the development effects of strong-heterogeneity gas reservoirs and ensure the long-term stable production of supergiant water-bearing gas reservoirs.The research results can be used as reference for the efficient development of similar domestic and foreign gas fields.
基金supported by the National Natural Science Foundation of China(Grant Nos.12288102,12033003,and 11633002)the Ma Huateng Foundation+4 种基金the Scholar Program of Beijing Academy of Science and Technology(Grant No.DZ:BS202002)the Tencent Xplorer Prizesponsored(in part)by the Chinese Academy of Sciences(CAS)through a grant to the CAS South America Center for Astronomy(CASSACA)in Santiago,ChileFunding for the LJT has been provided by the CAS and the People’s Government of Yunnan Province。
文摘Stars with initial masses in the range of 8-25 solar masses are thought to end their lives as hydrogen-rich supernovae(SNeⅡ).Based on the pre-explosion images of Hubble space telescope(HST)and Spitzer space telescope,we place tight constraints on the progenitor candidate of type IIP SN 2023ixf in Messier 101.Fitting of the spectral energy distribution(SED)of its progenitor with dusty stellar spectral models results in an estimation of the effective temperature as 3091+422-258K.The luminosity is estimated as lg(L/L⊙)~4.83,consistent with a red supergiant(RSG)star with an initial mass of 12-1+2M⊙.The derived mass loss rate(6×10^(-6)-9×10^(-6)M⊙yr^(-1))is much lower than that inferred from the flash spectroscopy of the SN,suggesting that the progenitor experienced a sudden increase in mass loss when approaching the final explosion.In the infrared bands,significant deviation from the range of regular RSGs in the color-magnitude diagram and period-luminosity space of the progenitor star indicates enhanced mass loss and dust formation.Combined with new evidence of polarization at the early phases of SN 2023ixf,such a violent mass loss is likely a result of binary interaction.
