Central Europe has faced major disasters causing fluctuations in salvage logging.These events,driven by natural or human factors,have damaged forest.Climate change is a key factor that cyclically affects these pattern...Central Europe has faced major disasters causing fluctuations in salvage logging.These events,driven by natural or human factors,have damaged forest.Climate change is a key factor that cyclically affects these patterns.These forest disasters cause billions in financial losses due to lower wood prices and quality,but their regular cycles are poorly understood.The objective of this study is to conduct a comprehensive analysis of salvage logging in Austria,Czechia,and Slovakia.Analyses indicate an upward trend in bark beetle-induced logging over the past five decades,with a notable surge in salvage logging in recent years.Cyclical fluctuations linked to solar activity represented by total solar irradiance(TSI)have been observed across the data.Higher TSI reduces beetle-induced logging to 3%-5%,while lower TSI increases it to 17%-24% near the solar minimum.An increase to higher seasonal temperature and a decrease to low precipitation one year before leads to a peak in beetle-induced logging,caused by drought.Seasonal precipitation and the North Atlantic Oscillation(NAO)have less impact,but higher precipitation is seen one year after the peak in bark-beetle logging.Droughts regularly occur one year before calamity peaks,confirmed by the Standardized Precipitation Evapotranspiration Index(SPEI).Harvests caused by wind and snow events have shorter cycles compared to the longer and more regular cycles of bark beetle-induced harvest.Common wavelet power spectrum analysis revealed a consistent 9-to 12-year cycle across all data sets.Solar cycle significantly impacts forest management through the NAO,precipitation,and temperature.The study suggests the potential for utilizing cyclical relationships in calamity prediction and more effective forest management in Central Europe.展开更多
I present the results oféchelle spectroscopy of a bright H II region in the irregular galaxy IC 4662 and their comparison with results from long-slit spectroscopy of the same region.All observations were obtained...I present the results oféchelle spectroscopy of a bright H II region in the irregular galaxy IC 4662 and their comparison with results from long-slit spectroscopy of the same region.All observations were obtained with the standard spectrographs of the Southern African Large Telescope:(1)low and medium spectral resolution spectrograph Robert Stobie Spectrograph(R≈800)and(2)échelle spectrograph HRS(R=16,000–1,7000).In both types of data the intensities of most of the emission lines were measured and abundances of oxygen and N Ne,S,Ar,Cl and Fe were determined as well as physical parameters of the H II region.The chemical abundances were obtained from both types of data with the Te-method.Abundances calculated from both types of data agree to within the cited uncertainties.The analysis of theéchelle data revealed three distinct kinematic subsystems within the studied H II region:a narrow component(NC,σ≈12 km s^(-1)),a broad component(BC,σ≈40 km s^(-1)),and a very broad component(VBC,σ≈60–110 km s^(-1),detected only in the brightest emission lines).The elementa abundances for the NC and BC subsystems were determined using the Te-method.The velocity dispersion dependence on the ionization potential of elements showed no correlation for the NC,indicating a well-mixed turbulent medium,while the BC exhibited pronounced stratification,characteristic of an expanding shell.Based on a detailed analysis of the kinematics and chemical composition,it was concluded that the BC is associated with the region surrounding a Wolf-Rayet(WR)star of spectral type WN7-8.The stellar wind from this WR star interacts with a shell ejected during an earlier evolutionary stage(either as a red supergiant or a luminous blue variable LBV),which is enriched in nitrogen.These findings highlight the importance of high spectral resolution for detecting small-scale(25 pc)chemical inhomogeneities and for understanding the feedback mechanisms of massive stars in low-metallicity environments.展开更多
This study explores the dynamics of charged Hayward black holes,focusing on the effects of electric charge and the length factor on accretion disk characteristics.Our results show that increasing both parameters reduc...This study explores the dynamics of charged Hayward black holes,focusing on the effects of electric charge and the length factor on accretion disk characteristics.Our results show that increasing both parameters reduces the size of the event horizon and innermost stable circular orbits(ISCO)radius,with the electric charge exerting a more pronounced influence.Additionally,the length factor and electric charge can effectively replicate the spin of a Kerr black hole.Both parameters also affect the electromagnetic radiation emitted from the accretion disk,increasing the flux,temperature,and radiative efficiency.The peak radiation occurs in the soft x-ray band,with higher values of electric charge and length factor enhancing disk luminosity and shifting the peak to higher frequencies.These findings can offer valuable insights into the accretion processes around black holes and their observable signatures,particularly in x-ray astronomy.展开更多
The Tashkent region is one of the most tectonically and seismically active areas in Uzbekistan. Although it is highly significant, the understanding and quantification of current deformation processes are still incomp...The Tashkent region is one of the most tectonically and seismically active areas in Uzbekistan. Although it is highly significant, the understanding and quantification of current deformation processes are still incomplete, especially concerning space-based geodetic techniques like the Global Navigation Satellite System(GNSS). Using velocity field data from 16 permanent GNSS sites during 2018-2023, this paper analyzes the strain rate field and its spatial characteristics using an improved least squares collocation method. The results indicate a northeastward motion consistent with India-Eurasian convergence, with velocities ranging from 24.7 to 30.1 mm/yr and increasing from northwest to southeast. The region displays substantial positive dilation at a rate of 14.7 nanostrain/yr, while the neighboring areas demonstrate negative dilation ranging from-10 to-30 nanostrain/yr. The second strain rate invariant with an average value of 20 nanostrain/yr primarily occurs along the Karzhantau fault. The spatial features of strain rate fields delineate the extensional and compressional strain zones, bounded in the west by the Tien Shan orogenic belt. Therefore, these zones warrant increased attention due to their relatively higher seismic risk in the Tashkent region.展开更多
We conducted an analysis of the continuum during the onset and initial decline phases of the 2023 outburst in transient neutron star low-mass X-ray binary Aql X–1 using broadband observations from the Hard X-ray Modu...We conducted an analysis of the continuum during the onset and initial decline phases of the 2023 outburst in transient neutron star low-mass X-ray binary Aql X–1 using broadband observations from the Hard X-ray Modulation Telescope(Insight-HXMT)instrument.To determine the most appropriate model for the continuum of this outburst,we employed three models to explore the evolution of the spectral component.These observations revealed that the source transitions from the hard state to the soft state.The disk-corona and sphere-corona models both adequately described the spectra of the hard state,while the double blackbody model became preferable after the hard X-ray emission(>25 keV)disappeared during the state transition.In the soft state,the total emission is dominated by the accretion disk and two blackbody components.The combination of the sphere-corona model and the double blackbody model is the most suitable model for this outburst.The results suggest that as the source transitioned into the soft state,the emission from the boundary layer was enhanced,and a hot spot occurred.Notably,we identified two type-ⅠX-ray bursts,one of which exhibited a significant hard X-ray deficit(significance~4.82σ),which indicates that Insight-HXMT has the capability to capture the evolution of the corona in a single burst.展开更多
We present a detailed analysis of a double-lined spectroscopic binary system,Bo Gem,using data obtained from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)and the Transiting Exoplanet Survey Sat...We present a detailed analysis of a double-lined spectroscopic binary system,Bo Gem,using data obtained from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)and the Transiting Exoplanet Survey Satellite(TESS).By applying spectral disentangling techniques to the LAMOST Medium Resolution Spectra,we determine the orbital parameters,including the orbital period of P=4.0689 days,and semimajor axis of a=14.90±0.04 R_(⊙).The mass ratio between the two components is found to be q=0.198±0.006,with an inclination of i=82°.3±0°.13.The photometric data from TESS revealed periodic light variations due to the eclipsing nature of the system,allowing for the determination of the primary star’s radius as R_(1)=1.68±0.03 R_(⊙)and the secondary star’s radius as R_(2)=3.68±0.04 R_(⊙).The effective temperatures of the primary and secondary stars are measured to be T_(eff,1)=9705±50 K and T_(eff,2)=5830±22 K,respectively.By analyzing the disentangled spectra,we determined the stellar atmospheric parameters—including surface gravity and metallicity of both stars.These results not only confirm the double-lined spectroscopic binary status of Bo Gem,but also underscore its value as an important system for testing and refining stellar evolution models.展开更多
We present the results of our study of the long-period eclipsing binary star V454 Aur.The results are based on spectroscopic data obtained with the UFESéchelle spectrograph and photometric observations from Trans...We present the results of our study of the long-period eclipsing binary star V454 Aur.The results are based on spectroscopic data obtained with the UFESéchelle spectrograph and photometric observations from Transiting Exoplanet Survey Satellite(TESS).The derived radial velocity curve is based on 17 spectra obtained between 2021and 2023,covering all orbital phases of this binary system.The orbital period determined from TESS data,P=27.019803±0.000003 days,agrees within uncertainties with the period established in previous studies.The model constructed for the TESS photometric light curve achieves a precision of 0.01%.The effective temperatures of both components,as well as the system metallicity,were directly derived from the spectra and are Teff,A=6250±50 K,Teff,B=5855±50 K,and[Fe/H]=-0.10±0.08,respectively.Our analysis of the photometric and spectroscopic data allowed us to directly compute the luminosities of the components,LA=1.82 L☉and LB=1.07 L☉,their radii,RA=1.15 R☉and RB=1.00 R☉,and their masses,MA=1.137 M☉and MB=1.023 M☉,with uncertainties below 1%.Comparison with evolutionary tracks indicates that the system’s age is 1.18±0.10 Gyr,and both components are still on the main sequence.The V454 Aur system is particularly interesting due to the partial eclipse of the primary component,which results in the“inversion”of the primary and secondary minima in the photometric light curve.展开更多
Phosphorus(P)deficiency is a major constraint in rice production,causing significant reductions in growth and yield.While P deficiency typically decreases chlorophyll content in many plant species,our previous studies...Phosphorus(P)deficiency is a major constraint in rice production,causing significant reductions in growth and yield.While P deficiency typically decreases chlorophyll content in many plant species,our previous studies revealed an unexpected increase in chlorophyll content in P-deficient rice seedlings.Here,we investigated this phenomenon in KDML105 rice under various P regimes and analyzed the physiological mechanisms involved.We found that P-deficient rice seedlings significantly increased chlorophyll a,chlorophyll b,and carotenoid contents in young leaves while reducing photosystem II quantum yield and enhancing non-photochemical quenching.This response was specific to P deficiency and was not observed under other stress conditions such as salinity or copper toxicity,which induced oxidative stress.Time-course experiments revealed that increased chlorophyll accumulation was an early adaptive response that occurred primarily in young leaves,while older leaves eventually developed chlorosis under prolonged P deficiency.The increased chlorophyll content may be attributed to reduced leaf width and altered leaf morphology under P-limited conditions.Furthermore,using custom hyperspectral imaging analysis coupled with machine learning classification,we successfully differentiated P status in rice leaves with 98.96%accuracy in older leaves.This study demonstrates that enhanced chlorophyll accumulation is a characteristic early response to P deficiency in rice,rather than a typical general stress response observed in other conditions.Our findings highlight the limitations of relying solely on chlorophyll-based indices as indicators of plant health in precision agriculture,especially regarding phosphorus(P)nutrition management.This underscores the need for a more comprehensive approach and lays the groundwork for developing advanced remote sensing technologies aimed at accurately assessing P status in rice cultivation.展开更多
We present the discovery of TCP J07222683+6220548,a new ultracompact binary system of the AM CVn type.This system was first identified displaying aΔV=7.6 mag outburst on 2025-01-20.9416 UTC by the New Milky Way wide-...We present the discovery of TCP J07222683+6220548,a new ultracompact binary system of the AM CVn type.This system was first identified displaying aΔV=7.6 mag outburst on 2025-01-20.9416 UTC by the New Milky Way wide-field survey for transients and later independently detected by ASAS-SN and ZTF.The outburst peaked at V_(max)=12.45 and lasted for seven days,followed by a series of rebrightenings.No previous outbursts are found in archival data.Positive superhumps with a period of 0.032546±0.000084 day(46.87±0.12 minutes),barely detectable during the main outburst,became clearly visible during the first rebrightening that lasted from day 18 to day 24 after the initial outburst.No convincing change in the superhump period was detected.Dense time-series photometry follow-up by a pair of 0.5 m INASAN robotic telescopes,together with VSNET and AAVSO observers,was essential for identifying TCP J07222683+6220548 as an AM CVn system and triggering confirmation spectroscopy with the 2.5 m CMO SAI telescope.Some outbursting AM CVn systems lacking such detailed follow-up may remain unrecognized among the newly discovered cataclysmic variable candidates.展开更多
The analysis of Earth’s crust movement vertical velocities was made both for separate regions, and averaged on regions. As input data coordinates and velocities of earth crust points, obtained in International Coordi...The analysis of Earth’s crust movement vertical velocities was made both for separate regions, and averaged on regions. As input data coordinates and velocities of earth crust points, obtained in International Coordinate Systems ITRF2000, ITRF2005,ITRF2008 on the base of processing radio interferometric(VLBI), laser(SLR), Doppler(DORIS) and GPS observations was used. For the purpose of global analysis all input velocity values were averaged in the x trapezoids. For filling trapezoids the spherical function expansion to N=36 was made. Expansion harmonic coefficients allowed determine the global characteristics of earth crust movements both for all Earth, and for separate hemispheres, polar and equatorial regions, continents and oceans. It appears, that polar regions were risen, and equatorial ones were lowered, that can indicate the modern Earth oblateness reduction. The constructed maps of vertical velocities were compared with obtained by us map of earth crust strain distribution. It is appeared, that regions of modern earth surface rising(Fennoscandia, Canada, Antarctica) coincide with regions of vertical extension strain, and the lowering regions-with compression regions. Simultaneously with the determination of harmonious coefficients the mean-square error of approximation for expansion of power n=1 N and power dispersion were determined. Whereas the results converge badly and dispersion increased with the n grows, hence we can concludes, that vertical movements do not characterized global earth crust movement and denotes the unrelated character of these movement. Seemingly, the main cause of such movement origin is the local seismic events(earthquake, volcanic eruption and so on). It confirms by our conclusions about correspondence of vertical strain maximal gradient(and therefore vertical velocities) map of the earthquake distribution. In work the detailed analysis of obtained results for separate Earth’s regions was made.展开更多
Using multichannel singular spectrum analysis （MSSA） we decomposed climatic time se- ries into principal components, and compared them with Earth rotation parameters. The global warming trends were initially subtrac...Using multichannel singular spectrum analysis （MSSA） we decomposed climatic time se- ries into principal components, and compared them with Earth rotation parameters. The global warming trends were initially subtracted. Similar quasi 60 and 20 year periodic os- cillations have been found in the global mean Earth temperature anomaly （HadCRUT4） and global mean sea level （GMSL）. Similar cycles were also found in Earth rotation variation. Over the last 160 years multi-decadal change of Earth＇s rotation velocity is correlated with the 60-year temperature anomaly, and Chandler wobble envelope reproduces the form of the 60-year oscillation noticed in GMSL. The quasi 20-year oscillation observed in GMSL is correlated with the Chandler wobble excitation. So, we assume that Earth＇s rotation and climate indexes are connected. Despite of all the clues hinting this connection, no sound conclusion can be done as far as ocean circulation modelling is not able to correctly catch angular momentum of the oscillatory modes.展开更多
In the physics of solar flares, it is crucial to diagnose the physical conditions near the flare energy- release sites. However, so far it is unclear how to diagnose these physical conditions. A solar microwave type I...In the physics of solar flares, it is crucial to diagnose the physical conditions near the flare energy- release sites. However, so far it is unclear how to diagnose these physical conditions. A solar microwave type III burst is believed to be a sensitive signature of primary energy release and electron accelerations in solar flares. This work takes into account the effect of the magnetic field on the plasma density and develops a set of formulas which can be used to estimate the plasma density, temperature, magnetic field near the magnetic reconnection site and particle acceleration region, and the velocity and energy of electron beams. We apply these formulas to three groups of microwave type III pairs in an X-class flare, and obtained some reasonable and interesting results. This method can be applied to other microwave type III bursts to diagnose the physical conditions of source regions, and provide some basic information to understand the intrinsic nature and fundamental processes occurring near the flare energy-release sites.展开更多
The density inhomogeneity of a glass pendulum is determined by an optical interference method. The relative variations of the densities over a volume with sizes of 5 × 5×5 mm^3 are （0.64 ± 0.97） ×...The density inhomogeneity of a glass pendulum is determined by an optical interference method. The relative variations of the densities over a volume with sizes of 5 × 5×5 mm^3 are （0.64 ± 0.97） × 10^-5 and （0.99 ± 0.92） × 10^-5 for the K9 glass and silica glass pendulum, respectively. These variations of densities contributing to the relative uncertainties of the Newtonian gravitational constant G are 0.20 ppm and 0.21 ppm in our experiment on measurement of G.展开更多
The research presented in this paper discusses the impact that the parameters of charge(Q)and screening factor(γ)have on properties of the horizon and silhouette of rotating charged Mod Max black holes which were rev...The research presented in this paper discusses the impact that the parameters of charge(Q)and screening factor(γ)have on properties of the horizon and silhouette of rotating charged Mod Max black holes which were reviewed in[Eur.Phys.J.C(2022)82:1155]recently,building upon previous findings in the field.Furthermore,the study explores the behavior of null geodesics,which can help us better understand the apparent shape of the black hole’s silhouette,as well as the distortion parameter and approximate radii of the silhouette that are influenced by the aforementioned parameters,and there are some values of parameter Q which corresponds to data from the Event Horizon Telescope(EHT).Notably,we explore the distortion parameter and approximate radii of the silhouette,revealing that while an increase inγleads to a growth in silhouette radius(Rs),it simultaneously reduces the distortion rate(δs).Conversely,heightened Q charge results in a reduction of Rsaccompanied by an increase inδs.Lastly,the paper analyzes the effects of the black hole’s parameters on the effective potential and energy emission:the peak value of the energy emission rate experiences a decrease as the screening factor(γ)increases,while it increases with higher values of the charge parameter(Q).展开更多
The ＂vip star＂ of AD185, recorded in the ancient Chinese history the Houhanshu, has been widely regarded as a supernova. However, some authors have suggested that the vip star might have been a comet. It has als...The ＂vip star＂ of AD185, recorded in the ancient Chinese history the Houhanshu, has been widely regarded as a supernova. However, some authors have suggested that the vip star might have been a comet. It has also been proposed that the record is the concatenation of a nova with a comet made by an early compiler. We have checked the record of the vip star, comparing it with records of comets in the same history. We find that most descriptions of comets clearly indicate motion, whereas the record of the vip star does not. We further argue that the term ＂yan＂ used to describe the star＇s ＂size＂ might be short for yanchuang （seat bed）, and ＂half a yan＂ would be simply as an imaginary figuration of the ancient observer. Moreover, we show that the term ＂hou -year＂ （hou-nian） most probably means the year after next. We argue that the asterism Southern Gate consisted of the stars α andβ Cen. We conclude that the record describing the vip star of AD 185 is completely different from any comet record in the same history, and that it almost certainly was a supernova.展开更多
The NASA Kepler mission obtained long-term high-quality photometric observations for a large number of stars in its original field of view from 2009 to 2013.To provide reliable stellar parameters in a homogeneous way,...The NASA Kepler mission obtained long-term high-quality photometric observations for a large number of stars in its original field of view from 2009 to 2013.To provide reliable stellar parameters in a homogeneous way,the LAMOST telescope began to carry out low-resolution spectroscopic observations for as many stars as possible in the Kepler field in 2012.By June 2018,238386 low-resolution spectra with SNRg≥6 had been collected for 155623 stars in the Kepler field,enabling the determination of atmospheric parameters and radial velocities,as well as spectral classification of the target stars.This information has been used by astronomers to carry out research in various fields,including stellar pulsations and asteroseismology,exoplanets,stellar magnetic activity and flares,peculiar stars and the Milky Way,binary stars,etc.We summarize the research progress in these fields where the usage of data from the LAMOST-Kepler(LK)project has played a role.In addition,time-domain medium-resolution spectroscopic observations have been carried out for about 12000 stars in four central plates of the Kepler field since 2018.The currently available results show that the LAMOST-Kepler medium resolution(LKMRS)observations provide qualified data suitable for research in additional science projects including binaries,high-amplitude pulsating stars,etc.As LAMOST is continuing to collect both low-and mediumresolution spectra of stars in the Kepler field,we expect more data to be released continuously and new scientific results to appear based on the LK project data.展开更多
In this paper,CCD photometric light curves for the short-period eclipsing binary 1 SWASP J140533.33＋114639.1（hereafter J1405） in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devin...In this paper,CCD photometric light curves for the short-period eclipsing binary 1 SWASP J140533.33＋114639.1（hereafter J1405） in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devinney（W-D） code. It is discovered that J1405 is a W-subtype shallow contact binary with a contact degree of f = 7.9±0.5% and a mass ratio of q = 1.55±0.02. In order to explain the asymmetric light curves of the system,a cool starspot on the more massive component is employed. This shallow contact eclipsing binary may have been formed from a short-period detached system through orbital shrinkage due to angular momentum loss. Based on the（O-C） method,the variation of orbital period is studied using all the available times of minimum light. The（O-C） diagram reveals that the period is increasing continuously at a rate of d P/dt = ＋2.09×10^-7 d yr^-1,which can be explained by mass transfer from the less massive component to the more massive one.展开更多
According to the space-geodetic data recorded at globally distributed stations over solid land spanning a period of more than 20-years under the International Terrestrial Reference Frame 2008,our previous estimate of ...According to the space-geodetic data recorded at globally distributed stations over solid land spanning a period of more than 20-years under the International Terrestrial Reference Frame 2008,our previous estimate of the average-weighted vertical variation of the Earth＇s solid surface suggests that the Earth＇s solid part is expanding at a rate of 0.24 ± 0.05 mm/a in recent two decades.In another aspect,the satellite altimetry observations spanning recent two decades demonstrate the sea level rise（SLR） rate 3.2 ± 0.4 mm/a,of which1.8 ± 0.5 mm/a is contributed by the ice melting over land.This study shows that the oceanic thermal expansion is 1.0 ± 0.1 mm/a due to the temperature increase in recent half century,which coincides with the estimate provided by previous authors.The SLR observation by altimetry is not balanced by the ice melting and thermal expansion,which is an open problem before this study.However,in this study we infer that the oceanic part of the Earth is expanding at a rate about 0.4 mm/a.Combining the expansion rates of land part and oceanic part,we conclude that the Earth is expanding at a rate of 0.35 ± 0.47 mm/a in recent two decades.If the Earth expands at this rate,then the altimetry-observed SLR can be well explained.展开更多
基金financial support from the Ministry of Agriculture of the Czech Republic through Project No.QK21010198,named Adaptation of forestry for sustainable use of natural resourcessupported by the project RVO:67985815supported by the Czech University of Life Sciences Prague,Faculty of Forestry and Wood Sciences(Excellent Output 2025).
文摘Central Europe has faced major disasters causing fluctuations in salvage logging.These events,driven by natural or human factors,have damaged forest.Climate change is a key factor that cyclically affects these patterns.These forest disasters cause billions in financial losses due to lower wood prices and quality,but their regular cycles are poorly understood.The objective of this study is to conduct a comprehensive analysis of salvage logging in Austria,Czechia,and Slovakia.Analyses indicate an upward trend in bark beetle-induced logging over the past five decades,with a notable surge in salvage logging in recent years.Cyclical fluctuations linked to solar activity represented by total solar irradiance(TSI)have been observed across the data.Higher TSI reduces beetle-induced logging to 3%-5%,while lower TSI increases it to 17%-24% near the solar minimum.An increase to higher seasonal temperature and a decrease to low precipitation one year before leads to a peak in beetle-induced logging,caused by drought.Seasonal precipitation and the North Atlantic Oscillation(NAO)have less impact,but higher precipitation is seen one year after the peak in bark-beetle logging.Droughts regularly occur one year before calamity peaks,confirmed by the Standardized Precipitation Evapotranspiration Index(SPEI).Harvests caused by wind and snow events have shorter cycles compared to the longer and more regular cycles of bark beetle-induced harvest.Common wavelet power spectrum analysis revealed a consistent 9-to 12-year cycle across all data sets.Solar cycle significantly impacts forest management through the NAO,precipitation,and temperature.The study suggests the potential for utilizing cyclical relationships in calamity prediction and more effective forest management in Central Europe.
基金support from the National Research Foundation(NRF)of South Africa。
文摘I present the results oféchelle spectroscopy of a bright H II region in the irregular galaxy IC 4662 and their comparison with results from long-slit spectroscopy of the same region.All observations were obtained with the standard spectrographs of the Southern African Large Telescope:(1)low and medium spectral resolution spectrograph Robert Stobie Spectrograph(R≈800)and(2)échelle spectrograph HRS(R=16,000–1,7000).In both types of data the intensities of most of the emission lines were measured and abundances of oxygen and N Ne,S,Ar,Cl and Fe were determined as well as physical parameters of the H II region.The chemical abundances were obtained from both types of data with the Te-method.Abundances calculated from both types of data agree to within the cited uncertainties.The analysis of theéchelle data revealed three distinct kinematic subsystems within the studied H II region:a narrow component(NC,σ≈12 km s^(-1)),a broad component(BC,σ≈40 km s^(-1)),and a very broad component(VBC,σ≈60–110 km s^(-1),detected only in the brightest emission lines).The elementa abundances for the NC and BC subsystems were determined using the Te-method.The velocity dispersion dependence on the ionization potential of elements showed no correlation for the NC,indicating a well-mixed turbulent medium,while the BC exhibited pronounced stratification,characteristic of an expanding shell.Based on a detailed analysis of the kinematics and chemical composition,it was concluded that the BC is associated with the region surrounding a Wolf-Rayet(WR)star of spectral type WN7-8.The stellar wind from this WR star interacts with a shell ejected during an earlier evolutionary stage(either as a red supergiant or a luminous blue variable LBV),which is enriched in nitrogen.These findings highlight the importance of high spectral resolution for detecting small-scale(25 pc)chemical inhomogeneities and for understanding the feedback mechanisms of massive stars in low-metallicity environments.
文摘This study explores the dynamics of charged Hayward black holes,focusing on the effects of electric charge and the length factor on accretion disk characteristics.Our results show that increasing both parameters reduces the size of the event horizon and innermost stable circular orbits(ISCO)radius,with the electric charge exerting a more pronounced influence.Additionally,the length factor and electric charge can effectively replicate the spin of a Kerr black hole.Both parameters also affect the electromagnetic radiation emitted from the accretion disk,increasing the flux,temperature,and radiative efficiency.The peak radiation occurs in the soft x-ray band,with higher values of electric charge and length factor enhancing disk luminosity and shifting the peak to higher frequencies.These findings can offer valuable insights into the accretion processes around black holes and their observable signatures,particularly in x-ray astronomy.
基金funding of the Academy of Sciences of the Republic of Uzbekistan
文摘The Tashkent region is one of the most tectonically and seismically active areas in Uzbekistan. Although it is highly significant, the understanding and quantification of current deformation processes are still incomplete, especially concerning space-based geodetic techniques like the Global Navigation Satellite System(GNSS). Using velocity field data from 16 permanent GNSS sites during 2018-2023, this paper analyzes the strain rate field and its spatial characteristics using an improved least squares collocation method. The results indicate a northeastward motion consistent with India-Eurasian convergence, with velocities ranging from 24.7 to 30.1 mm/yr and increasing from northwest to southeast. The region displays substantial positive dilation at a rate of 14.7 nanostrain/yr, while the neighboring areas demonstrate negative dilation ranging from-10 to-30 nanostrain/yr. The second strain rate invariant with an average value of 20 nanostrain/yr primarily occurs along the Karzhantau fault. The spatial features of strain rate fields delineate the extensional and compressional strain zones, bounded in the west by the Tien Shan orogenic belt. Therefore, these zones warrant increased attention due to their relatively higher seismic risk in the Tashkent region.
基金supported by the National Key R&D Program of China(2023YFE0101200)supported by the National Key R&D Program of China(2021YFA0718500)+3 种基金Yunnan Revitalization Talent Support Program(Yun Ling Scholar Award)the National Natural Science Foundation of China(NSFC)grant 12393813the science research grants from the China Manned Space Projectsupported by Hunan Education Department Foundation(grant No.21A0096)。
文摘We conducted an analysis of the continuum during the onset and initial decline phases of the 2023 outburst in transient neutron star low-mass X-ray binary Aql X–1 using broadband observations from the Hard X-ray Modulation Telescope(Insight-HXMT)instrument.To determine the most appropriate model for the continuum of this outburst,we employed three models to explore the evolution of the spectral component.These observations revealed that the source transitions from the hard state to the soft state.The disk-corona and sphere-corona models both adequately described the spectra of the hard state,while the double blackbody model became preferable after the hard X-ray emission(>25 keV)disappeared during the state transition.In the soft state,the total emission is dominated by the accretion disk and two blackbody components.The combination of the sphere-corona model and the double blackbody model is the most suitable model for this outburst.The results suggest that as the source transitioned into the soft state,the emission from the boundary layer was enhanced,and a hot spot occurred.Notably,we identified two type-ⅠX-ray bursts,one of which exhibited a significant hard X-ray deficit(significance~4.82σ),which indicates that Insight-HXMT has the capability to capture the evolution of the corona in a single burst.
基金supported by the National Key R&D Program of China for the Intergovernmental Scientific and Technological Innovation Cooperation Project under No.2022YFE0126200Tianshan Talent Training Program under No.2023TSYCLJ0053+3 种基金supported by the National Natural Science Foundation of China under grant Nos.12090040/4,12022304,11973052,11973042,U1931102,12373036the National Key R&D Program of China No.2019YFA0405502support from the Guo Shou Jing TelescopeGuo Shou Jing Telescope(the Large Sky Area Multi-Object Fiber Spectroscopic Telescope LAMOST)is a National Major Scientific Project built by the Chinese Academy of Sciences.Funding for the project has been provided by the National Development and Reform Commission.
文摘We present a detailed analysis of a double-lined spectroscopic binary system,Bo Gem,using data obtained from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)and the Transiting Exoplanet Survey Satellite(TESS).By applying spectral disentangling techniques to the LAMOST Medium Resolution Spectra,we determine the orbital parameters,including the orbital period of P=4.0689 days,and semimajor axis of a=14.90±0.04 R_(⊙).The mass ratio between the two components is found to be q=0.198±0.006,with an inclination of i=82°.3±0°.13.The photometric data from TESS revealed periodic light variations due to the eclipsing nature of the system,allowing for the determination of the primary star’s radius as R_(1)=1.68±0.03 R_(⊙)and the secondary star’s radius as R_(2)=3.68±0.04 R_(⊙).The effective temperatures of the primary and secondary stars are measured to be T_(eff,1)=9705±50 K and T_(eff,2)=5830±22 K,respectively.By analyzing the disentangled spectra,we determined the stellar atmospheric parameters—including surface gravity and metallicity of both stars.These results not only confirm the double-lined spectroscopic binary status of Bo Gem,but also underscore its value as an important system for testing and refining stellar evolution models.
基金support from the National Research Foundation(NRF)of South Africasupported by the Ministry of Science and Higher Education of Russia,topic No.FEUZ-2023-0019。
文摘We present the results of our study of the long-period eclipsing binary star V454 Aur.The results are based on spectroscopic data obtained with the UFESéchelle spectrograph and photometric observations from Transiting Exoplanet Survey Satellite(TESS).The derived radial velocity curve is based on 17 spectra obtained between 2021and 2023,covering all orbital phases of this binary system.The orbital period determined from TESS data,P=27.019803±0.000003 days,agrees within uncertainties with the period established in previous studies.The model constructed for the TESS photometric light curve achieves a precision of 0.01%.The effective temperatures of both components,as well as the system metallicity,were directly derived from the spectra and are Teff,A=6250±50 K,Teff,B=5855±50 K,and[Fe/H]=-0.10±0.08,respectively.Our analysis of the photometric and spectroscopic data allowed us to directly compute the luminosities of the components,LA=1.82 L☉and LB=1.07 L☉,their radii,RA=1.15 R☉and RB=1.00 R☉,and their masses,MA=1.137 M☉and MB=1.023 M☉,with uncertainties below 1%.Comparison with evolutionary tracks indicates that the system’s age is 1.18±0.10 Gyr,and both components are still on the main sequence.The V454 Aur system is particularly interesting due to the partial eclipse of the primary component,which results in the“inversion”of the primary and secondary minima in the photometric light curve.
基金supported by the Prince of Songkla University,Thailand(Grant No.SCI6602020S)。
文摘Phosphorus(P)deficiency is a major constraint in rice production,causing significant reductions in growth and yield.While P deficiency typically decreases chlorophyll content in many plant species,our previous studies revealed an unexpected increase in chlorophyll content in P-deficient rice seedlings.Here,we investigated this phenomenon in KDML105 rice under various P regimes and analyzed the physiological mechanisms involved.We found that P-deficient rice seedlings significantly increased chlorophyll a,chlorophyll b,and carotenoid contents in young leaves while reducing photosystem II quantum yield and enhancing non-photochemical quenching.This response was specific to P deficiency and was not observed under other stress conditions such as salinity or copper toxicity,which induced oxidative stress.Time-course experiments revealed that increased chlorophyll accumulation was an early adaptive response that occurred primarily in young leaves,while older leaves eventually developed chlorosis under prolonged P deficiency.The increased chlorophyll content may be attributed to reduced leaf width and altered leaf morphology under P-limited conditions.Furthermore,using custom hyperspectral imaging analysis coupled with machine learning classification,we successfully differentiated P status in rice leaves with 98.96%accuracy in older leaves.This study demonstrates that enhanced chlorophyll accumulation is a characteristic early response to P deficiency in rice,rather than a typical general stress response observed in other conditions.Our findings highlight the limitations of relying solely on chlorophyll-based indices as indicators of plant health in precision agriculture,especially regarding phosphorus(P)nutrition management.This underscores the need for a more comprehensive approach and lays the groundwork for developing advanced remote sensing technologies aimed at accurately assessing P status in rice cultivation.
基金support of the Foundation for the Development of Theoretical Physics and Mathematics BASIS(project 24-2-1-6-1)supported by the UKRI Science and Technology Facilities Council and is a collaboration between the University of Edinburgh(grant ST/N002512/1)and Queen’s University Belfast(grant ST/N002520/1)within the LSST:UK Science Consortium+4 种基金supported by the National Science Foundation under grants No.AST-1440341 and AST-2034437primarily funded to search for near earth asteroids through NASA grants NN12AR55G,80NSSC18K0284,and80NSSC18K1575partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889STFC grants ST/T000198/1 and ST/S006109/1made use of the Astrophysics Data System,funded by NASA under Cooperative Agreement 80NSSC21M00561。
文摘We present the discovery of TCP J07222683+6220548,a new ultracompact binary system of the AM CVn type.This system was first identified displaying aΔV=7.6 mag outburst on 2025-01-20.9416 UTC by the New Milky Way wide-field survey for transients and later independently detected by ASAS-SN and ZTF.The outburst peaked at V_(max)=12.45 and lasted for seven days,followed by a series of rebrightenings.No previous outbursts are found in archival data.Positive superhumps with a period of 0.032546±0.000084 day(46.87±0.12 minutes),barely detectable during the main outburst,became clearly visible during the first rebrightening that lasted from day 18 to day 24 after the initial outburst.No convincing change in the superhump period was detected.Dense time-series photometry follow-up by a pair of 0.5 m INASAN robotic telescopes,together with VSNET and AAVSO observers,was essential for identifying TCP J07222683+6220548 as an AM CVn system and triggering confirmation spectroscopy with the 2.5 m CMO SAI telescope.Some outbursting AM CVn systems lacking such detailed follow-up may remain unrecognized among the newly discovered cataclysmic variable candidates.
文摘The analysis of Earth’s crust movement vertical velocities was made both for separate regions, and averaged on regions. As input data coordinates and velocities of earth crust points, obtained in International Coordinate Systems ITRF2000, ITRF2005,ITRF2008 on the base of processing radio interferometric(VLBI), laser(SLR), Doppler(DORIS) and GPS observations was used. For the purpose of global analysis all input velocity values were averaged in the x trapezoids. For filling trapezoids the spherical function expansion to N=36 was made. Expansion harmonic coefficients allowed determine the global characteristics of earth crust movements both for all Earth, and for separate hemispheres, polar and equatorial regions, continents and oceans. It appears, that polar regions were risen, and equatorial ones were lowered, that can indicate the modern Earth oblateness reduction. The constructed maps of vertical velocities were compared with obtained by us map of earth crust strain distribution. It is appeared, that regions of modern earth surface rising(Fennoscandia, Canada, Antarctica) coincide with regions of vertical extension strain, and the lowering regions-with compression regions. Simultaneously with the determination of harmonious coefficients the mean-square error of approximation for expansion of power n=1 N and power dispersion were determined. Whereas the results converge badly and dispersion increased with the n grows, hence we can concludes, that vertical movements do not characterized global earth crust movement and denotes the unrelated character of these movement. Seemingly, the main cause of such movement origin is the local seismic events(earthquake, volcanic eruption and so on). It confirms by our conclusions about correspondence of vertical strain maximal gradient(and therefore vertical velocities) map of the earthquake distribution. In work the detailed analysis of obtained results for separate Earth’s regions was made.
基金supported by Russian Foundation for Basic Research (16-05-00753)partially supported by NSF/IGFA (ICER-1342644)
文摘Using multichannel singular spectrum analysis （MSSA） we decomposed climatic time se- ries into principal components, and compared them with Earth rotation parameters. The global warming trends were initially subtracted. Similar quasi 60 and 20 year periodic os- cillations have been found in the global mean Earth temperature anomaly （HadCRUT4） and global mean sea level （GMSL）. Similar cycles were also found in Earth rotation variation. Over the last 160 years multi-decadal change of Earth＇s rotation velocity is correlated with the 60-year temperature anomaly, and Chandler wobble envelope reproduces the form of the 60-year oscillation noticed in GMSL. The quasi 20-year oscillation observed in GMSL is correlated with the Chandler wobble excitation. So, we assume that Earth＇s rotation and climate indexes are connected. Despite of all the clues hinting this connection, no sound conclusion can be done as far as ocean circulation modelling is not able to correctly catch angular momentum of the oscillatory modes.
基金support by the National Natural Science Foundation of China(Grant Nos.11273030,11221063,11373039 and 11433006)MOST Grant(2014FY120300,CAS XDB09000000)+3 种基金the National Major Scientific Equipment R&D Project(ZDYZ 2009-3)support by the Grant P209/12/00103(GA CR)the research project(RVO:67985815)of the Astronomical Institute ASsupported by the Marie Curie PIRSES-GA-295272-RADIOSUN project
文摘In the physics of solar flares, it is crucial to diagnose the physical conditions near the flare energy- release sites. However, so far it is unclear how to diagnose these physical conditions. A solar microwave type III burst is believed to be a sensitive signature of primary energy release and electron accelerations in solar flares. This work takes into account the effect of the magnetic field on the plasma density and develops a set of formulas which can be used to estimate the plasma density, temperature, magnetic field near the magnetic reconnection site and particle acceleration region, and the velocity and energy of electron beams. We apply these formulas to three groups of microwave type III pairs in an X-class flare, and obtained some reasonable and interesting results. This method can be applied to other microwave type III bursts to diagnose the physical conditions of source regions, and provide some basic information to understand the intrinsic nature and fundamental processes occurring near the flare energy-release sites.
基金Supported by the National Basic Research Programme of China under Grant No 2003CB716300, the National Natural Science Foundation of China under Grant No 10121503, and Russian Foundation for Basic Research （No 05-02-39014）.
文摘The density inhomogeneity of a glass pendulum is determined by an optical interference method. The relative variations of the densities over a volume with sizes of 5 × 5×5 mm^3 are （0.64 ± 0.97） × 10^-5 and （0.99 ± 0.92） × 10^-5 for the K9 glass and silica glass pendulum, respectively. These variations of densities contributing to the relative uncertainties of the Newtonian gravitational constant G are 0.20 ppm and 0.21 ppm in our experiment on measurement of G.
基金partly supported by Research Grant F-FA-2021510 of the Uzbekistan Ministry for Innovative Developmentsupport received from the Scientific and Technological Research Council of Türkiye(TüBITAK),the Abdus Salam International Centre for Theoretical Physics,Trieste,Italy and the Sponsoring Consortium for Open Access Publishing in Particle Physics(SCOAP3)。
文摘The research presented in this paper discusses the impact that the parameters of charge(Q)and screening factor(γ)have on properties of the horizon and silhouette of rotating charged Mod Max black holes which were reviewed in[Eur.Phys.J.C(2022)82:1155]recently,building upon previous findings in the field.Furthermore,the study explores the behavior of null geodesics,which can help us better understand the apparent shape of the black hole’s silhouette,as well as the distortion parameter and approximate radii of the silhouette that are influenced by the aforementioned parameters,and there are some values of parameter Q which corresponds to data from the Event Horizon Telescope(EHT).Notably,we explore the distortion parameter and approximate radii of the silhouette,revealing that while an increase inγleads to a growth in silhouette radius(Rs),it simultaneously reduces the distortion rate(δs).Conversely,heightened Q charge results in a reduction of Rsaccompanied by an increase inδs.Lastly,the paper analyzes the effects of the black hole’s parameters on the effective potential and energy emission:the peak value of the energy emission rate experiences a decrease as the screening factor(γ)increases,while it increases with higher values of the charge parameter(Q).
基金Supported by the National Natural Science Foundation of China.
文摘The ＂vip star＂ of AD185, recorded in the ancient Chinese history the Houhanshu, has been widely regarded as a supernova. However, some authors have suggested that the vip star might have been a comet. It has also been proposed that the record is the concatenation of a nova with a comet made by an early compiler. We have checked the record of the vip star, comparing it with records of comets in the same history. We find that most descriptions of comets clearly indicate motion, whereas the record of the vip star does not. We further argue that the term ＂yan＂ used to describe the star＇s ＂size＂ might be short for yanchuang （seat bed）, and ＂half a yan＂ would be simply as an imaginary figuration of the ancient observer. Moreover, we show that the term ＂hou -year＂ （hou-nian） most probably means the year after next. We argue that the asterism Southern Gate consisted of the stars α andβ Cen. We conclude that the record describing the vip star of AD 185 is completely different from any comet record in the same history, and that it almost certainly was a supernova.
基金the support from the National Natural Science Foundation of China(NSFC,No.11833002)the Beijing Natural Science Foundation(No.1194023)。
文摘The NASA Kepler mission obtained long-term high-quality photometric observations for a large number of stars in its original field of view from 2009 to 2013.To provide reliable stellar parameters in a homogeneous way,the LAMOST telescope began to carry out low-resolution spectroscopic observations for as many stars as possible in the Kepler field in 2012.By June 2018,238386 low-resolution spectra with SNRg≥6 had been collected for 155623 stars in the Kepler field,enabling the determination of atmospheric parameters and radial velocities,as well as spectral classification of the target stars.This information has been used by astronomers to carry out research in various fields,including stellar pulsations and asteroseismology,exoplanets,stellar magnetic activity and flares,peculiar stars and the Milky Way,binary stars,etc.We summarize the research progress in these fields where the usage of data from the LAMOST-Kepler(LK)project has played a role.In addition,time-domain medium-resolution spectroscopic observations have been carried out for about 12000 stars in four central plates of the Kepler field since 2018.The currently available results show that the LAMOST-Kepler medium resolution(LKMRS)observations provide qualified data suitable for research in additional science projects including binaries,high-amplitude pulsating stars,etc.As LAMOST is continuing to collect both low-and mediumresolution spectra of stars in the Kepler field,we expect more data to be released continuously and new scientific results to appear based on the LK project data.
基金partly supported by the National Natural Science Foundation of China (Nos.11133007 and 11573063)the Science Foundation of Yunnan Province (Grant No.2012HC011)
文摘In this paper,CCD photometric light curves for the short-period eclipsing binary 1 SWASP J140533.33＋114639.1（hereafter J1405） in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devinney（W-D） code. It is discovered that J1405 is a W-subtype shallow contact binary with a contact degree of f = 7.9±0.5% and a mass ratio of q = 1.55±0.02. In order to explain the asymmetric light curves of the system,a cool starspot on the more massive component is employed. This shallow contact eclipsing binary may have been formed from a short-period detached system through orbital shrinkage due to angular momentum loss. Based on the（O-C） method,the variation of orbital period is studied using all the available times of minimum light. The（O-C） diagram reveals that the period is increasing continuously at a rate of d P/dt = ＋2.09×10^-7 d yr^-1,which can be explained by mass transfer from the less massive component to the more massive one.
基金supported by National 973 Project China(2013CB733305,2013CB733301)National Natural Science Foundation of China(41174011,41429401,41210006,41128003,41021061)
文摘According to the space-geodetic data recorded at globally distributed stations over solid land spanning a period of more than 20-years under the International Terrestrial Reference Frame 2008,our previous estimate of the average-weighted vertical variation of the Earth＇s solid surface suggests that the Earth＇s solid part is expanding at a rate of 0.24 ± 0.05 mm/a in recent two decades.In another aspect,the satellite altimetry observations spanning recent two decades demonstrate the sea level rise（SLR） rate 3.2 ± 0.4 mm/a,of which1.8 ± 0.5 mm/a is contributed by the ice melting over land.This study shows that the oceanic thermal expansion is 1.0 ± 0.1 mm/a due to the temperature increase in recent half century,which coincides with the estimate provided by previous authors.The SLR observation by altimetry is not balanced by the ice melting and thermal expansion,which is an open problem before this study.However,in this study we infer that the oceanic part of the Earth is expanding at a rate about 0.4 mm/a.Combining the expansion rates of land part and oceanic part,we conclude that the Earth is expanding at a rate of 0.35 ± 0.47 mm/a in recent two decades.If the Earth expands at this rate,then the altimetry-observed SLR can be well explained.
