Sulphur(S)is essential for the quality of oilseed crops,ranking as the fourth major nutrient after nitrogen(N),phosphorus(P),and potassium(K).While crops need sulphur in slightly lower amounts than phosphorus,maintain...Sulphur(S)is essential for the quality of oilseed crops,ranking as the fourth major nutrient after nitrogen(N),phosphorus(P),and potassium(K).While crops need sulphur in slightly lower amounts than phosphorus,maintaining optimum sulphur levels is crucial for oilseed yield and quality.Factors such as sulphur dynamics,impact of deficiency,application methods,and climate change must be addressed to improve agricultural practices.In South Asian countries like India,Pakistan,and Bangladesh,oilseeds are vital to the agricultural economy,supporting food security,livelihoods,and economic growth.However,climate change,marginal land cultivation,and a shift to more profitable crops like wheat and maize have led to a decline in oilseed productivity.Sulphur is particularly important for vital plant functions,including protein synthesis,chlorophyll formation,and resistance to abiotic stress.Proper management of sulphur can significantly enhance the yield,oil content,and seed quality.Sulphur fertilization improves crop resilience to pests,diseases,and environmental stresses,resulting in healthier plants.To optimize oilseed production,best practices for sulphur management like integrated nutrient management,regular soil testing,and the strategic application of sulphur-enriched fertilizers must be adopted.Despite its significance,many South Asian soils suffer from sulphur deficiency due to inadequate replenishment and reliance on high-analysis fertilizers.By enhancing sulphur availability,oilseed producers can significantly increase crop yields,improve oil content,and promote overall plant health,contributing to the agricultural economy and food security in the region.This manuscript aims to evaluate the critical role of sulphur in enhancing the yield,oil quality,and stress resilience of oilseed crops in South Asia.展开更多
Based on the RXTE observations of Sco X-1,we identified a clear dichotomy in the behavior of its X-ray crosscorrelation functions(CCFs)which is possibly associated with two different radio jet ejection events.Twenty s...Based on the RXTE observations of Sco X-1,we identified a clear dichotomy in the behavior of its X-ray crosscorrelation functions(CCFs)which is possibly associated with two different radio jet ejection events.Twenty six observations display asymmetric CCFs of low correlation coefficients with soft or hard delays of a few hundred seconds along with no oscillation feature in the power density spectrum associated with horizontal branch/hard apex.All the observations belonging to NB/FB have symmetric CCFs with NBO/NBO+HBO/FBO in the PDS.Based on radio observations,two different types of jets were associated with Sco X-1 i.e.,ballistic radio jets and an ultra-relativistic flow(URF).We noted that asymmetric CCFs with delays were connected with ballistic or lobe radio jets and symmetric CCFs with URFs in Sco X-1.We interpret these findings as evidence of two different states of the inner accretion disk.We propose that the launch of a ballistic jet triggers significant instability within the inner accretion region,likely the boundary layer and corona.This disruption explains the observed delays in the CCF and simultaneously quenches the conditions required for coherent oscillations,leaving only flat-topped noise in the PDS.We constrain the size of this unstable region in the inner region of accretion to be~10-40 km.In contrast,the symmetric CCFs and persistent oscillations(NBO/NBO+HBO)during URF events suggest a more stable,steady accretion flow.Although connecting the URF to a specific oscillation is difficult,its strong association with the NB phase of variation suggests a common underlying physical mechanism.Therefore,the CCF's asymmetry acts as a powerful diagnostic,linking ballistic jets to disk instability and URFs to a stable accretion state.Various physical scenarios are discussed to understand the connection among X-ray CCFs,PDS,and radio ejections in Sco X-1.展开更多
Marginal short-period contact binaries are important to understand as they pose a different physical scenario than the predicted theoretical model based on the thermal relaxation oscillation mechanism due to their sha...Marginal short-period contact binaries are important to understand as they pose a different physical scenario than the predicted theoretical model based on the thermal relaxation oscillation mechanism due to their shallow degree of contact.Here we present the optical and X-ray studies of a contact binary source RW Dor using the Transiting Exoplanet Survey Satellite(TESS)and XMM-Newton telescopes.For the first time we report the varying O'Connell effect and explain the asymmetry with a spot model.Based on the new times of minima,we make a robust estimate of the orbital period of the third body at 47.01~0.52 yr with an eccentricity e=0.21.We show that the period-decreasing trend observed in O-C variation can be explained by both conservative mass transfer from primary to secondary and AML via stellar wind.The X-ray luminosity exhibited by RW Dor did not vary significantly on three different occasions and was found to be about 3.34×10~(29)erg s~(-1).Assuming that the quiescent X-ray emission is emitted from an undisturbed loop structure,the loop size is estimated to be 0.6-1×10~(10)cm which is≤Alfvén radius r_A~8×10~(10)cm.展开更多
Contact binaries at various stages of evolution unveil various operating mechanisms that drive them.We report the photometric and period variation analysis of two contact binaries EV Cnc and AH Cnc in open cluster M67...Contact binaries at various stages of evolution unveil various operating mechanisms that drive them.We report the photometric and period variation analysis of two contact binaries EV Cnc and AH Cnc in open cluster M67.We observed the cluster from the JCBT 1.3 m telescope and utilized TESS and Kepler observations.The photometric solutions of EV Cnc and AH Cnc revealed a mass ratio of q~0.41 and~0.15 with an inclination of i=42°and87°respectively.These solutions suggest that EV Cnc is probably a semi-detached and AH Cnc is a deep low-mass ratio contact binary.The study of O-C variation analysis indicates that for both systems,the period is increasing which suggests the mass transfer is occurring from secondary to primary.In the case of AH Cnc and based on simulations by randomly varying the time of minima to fit the LITE solution,we noted the third body orbital period to be around P_(3)=26.82±2.54 yr,which is different from earlier reported values and conclude that future observations are required to confirm this scenario.We compare these two systems with other similar contact binaries to get an estimate of the final configuration of the respective systems.展开更多
Understanding the variation of lags with respect to the X-ray flux is important to explore the geometry of the inner region of the accretion disk in AGNs.We performed frequency-lag,energy–lag and spectral studies for...Understanding the variation of lags with respect to the X-ray flux is important to explore the geometry of the inner region of the accretion disk in AGNs.We performed frequency-lag,energy–lag and spectral studies for two sets of observations,in order to investigate the variations in lags with respect to X-ray flux in the AGN source Mrk 704 using the XMM-Newton observatory.We divided one of the light curves into two sections which were noticed to exhibit a flux variation.The frequency-lag spectra in different energy domains revealed that reverberation(soft)lags varied along with the flux.For the first time,we show that the blurred reflection model can consistently explain the soft excess observed in the X-ray spectra for this source.The fluxes of soft(i.e.,reflection)and hard components were noted to vary by~18%and~9%respectively,across the sections.The soft lag amplitude was found to be larger at the high flux state than the amplitude at the low flux state.Most importantly,we found that both frequency-lag and energy–lag spectra do not display significant variation between two observational data sets despite a flux variation of 43%.This phenomenon cannot be explained by the reflection model because the soft lag amplitudes must be larger in the high flux state.The probable scenario is that,in the low flux state,the obscuring cloud delays the reflected soft photons which increases the soft lag amplitude.展开更多
Marginal contact binary systems are an important class of binary systems in exploited by astronomers to understand various astrophysical phenomena as they bridge both semi-detached and overcontact stages.We studied th...Marginal contact binary systems are an important class of binary systems in exploited by astronomers to understand various astrophysical phenomena as they bridge both semi-detached and overcontact stages.We studied the photometric data of CW Aqr using the JCB 1.3 m telescope(JCBT),Kepler,and TESS to understand the period variations and constrain the light curve solutions.We noted that the period of CW Aqr is increasing with a mass transfer rate of m=7.53×10^(-8)M_(⊙)yr^(-1)from the secondary to the primary component.We also ascertained cyclic deviations along with a parabolic trend in the O-C diagram.The residuals displayed a sinusoidal trend which was fitted with an LTTE,indicating the presence of a third body with an orbital period of P_(3)~10 yr and e=0.10.We fitted the JCBT,Kepler,and TESS photometric normalized light curves and noted the mass ratio to be q~0.32 for both contact and semi-detached configurations.We identified a temperature difference between the primary and secondary components of~2500 K.No activity signatures were found in the observed light curves which were also evident from the Hαline studies where the filled-in effect was not seen.Overall our study suggests that CW Aqr is a marginal contact binary with a low mass ratio evolving toward a semi-detached configuration.However,it may merge if the period increases due to ongoing mass transfer accompanied by a lowering in the mass ratio and later oscillate back to the period-decreasing trend due to angular momentum loss over a few cycles of thermal relaxation oscillations followed by instability.展开更多
文摘Sulphur(S)is essential for the quality of oilseed crops,ranking as the fourth major nutrient after nitrogen(N),phosphorus(P),and potassium(K).While crops need sulphur in slightly lower amounts than phosphorus,maintaining optimum sulphur levels is crucial for oilseed yield and quality.Factors such as sulphur dynamics,impact of deficiency,application methods,and climate change must be addressed to improve agricultural practices.In South Asian countries like India,Pakistan,and Bangladesh,oilseeds are vital to the agricultural economy,supporting food security,livelihoods,and economic growth.However,climate change,marginal land cultivation,and a shift to more profitable crops like wheat and maize have led to a decline in oilseed productivity.Sulphur is particularly important for vital plant functions,including protein synthesis,chlorophyll formation,and resistance to abiotic stress.Proper management of sulphur can significantly enhance the yield,oil content,and seed quality.Sulphur fertilization improves crop resilience to pests,diseases,and environmental stresses,resulting in healthier plants.To optimize oilseed production,best practices for sulphur management like integrated nutrient management,regular soil testing,and the strategic application of sulphur-enriched fertilizers must be adopted.Despite its significance,many South Asian soils suffer from sulphur deficiency due to inadequate replenishment and reliance on high-analysis fertilizers.By enhancing sulphur availability,oilseed producers can significantly increase crop yields,improve oil content,and promote overall plant health,contributing to the agricultural economy and food security in the region.This manuscript aims to evaluate the critical role of sulphur in enhancing the yield,oil quality,and stress resilience of oilseed crops in South Asia.
基金the support of the DST-ANRF(Anusandhan National Research Foundation)Core Research Grant project,Government of India。
文摘Based on the RXTE observations of Sco X-1,we identified a clear dichotomy in the behavior of its X-ray crosscorrelation functions(CCFs)which is possibly associated with two different radio jet ejection events.Twenty six observations display asymmetric CCFs of low correlation coefficients with soft or hard delays of a few hundred seconds along with no oscillation feature in the power density spectrum associated with horizontal branch/hard apex.All the observations belonging to NB/FB have symmetric CCFs with NBO/NBO+HBO/FBO in the PDS.Based on radio observations,two different types of jets were associated with Sco X-1 i.e.,ballistic radio jets and an ultra-relativistic flow(URF).We noted that asymmetric CCFs with delays were connected with ballistic or lobe radio jets and symmetric CCFs with URFs in Sco X-1.We interpret these findings as evidence of two different states of the inner accretion disk.We propose that the launch of a ballistic jet triggers significant instability within the inner accretion region,likely the boundary layer and corona.This disruption explains the observed delays in the CCF and simultaneously quenches the conditions required for coherent oscillations,leaving only flat-topped noise in the PDS.We constrain the size of this unstable region in the inner region of accretion to be~10-40 km.In contrast,the symmetric CCFs and persistent oscillations(NBO/NBO+HBO)during URF events suggest a more stable,steady accretion flow.Although connecting the URF to a specific oscillation is difficult,its strong association with the NB phase of variation suggests a common underlying physical mechanism.Therefore,the CCF's asymmetry acts as a powerful diagnostic,linking ballistic jets to disk instability and URFs to a stable accretion state.Various physical scenarios are discussed to understand the connection among X-ray CCFs,PDS,and radio ejections in Sco X-1.
基金financial support from the SERB Core Research Grant project,the Government of Indiasupport from the SRF INSPIRE(IF 170314)fellowship program,Government of India。
文摘Marginal short-period contact binaries are important to understand as they pose a different physical scenario than the predicted theoretical model based on the thermal relaxation oscillation mechanism due to their shallow degree of contact.Here we present the optical and X-ray studies of a contact binary source RW Dor using the Transiting Exoplanet Survey Satellite(TESS)and XMM-Newton telescopes.For the first time we report the varying O'Connell effect and explain the asymmetry with a spot model.Based on the new times of minima,we make a robust estimate of the orbital period of the third body at 47.01~0.52 yr with an eccentricity e=0.21.We show that the period-decreasing trend observed in O-C variation can be explained by both conservative mass transfer from primary to secondary and AML via stellar wind.The X-ray luminosity exhibited by RW Dor did not vary significantly on three different occasions and was found to be about 3.34×10~(29)erg s~(-1).Assuming that the quiescent X-ray emission is emitted from an undisturbed loop structure,the loop size is estimated to be 0.6-1×10~(10)cm which is≤Alfvén radius r_A~8×10~(10)cm.
基金support from the SRF INSPIRE(IF 170314)fellowship program,Government of Indiafinancial support from the SERB Core Research Grant project,the Government of India。
文摘Contact binaries at various stages of evolution unveil various operating mechanisms that drive them.We report the photometric and period variation analysis of two contact binaries EV Cnc and AH Cnc in open cluster M67.We observed the cluster from the JCBT 1.3 m telescope and utilized TESS and Kepler observations.The photometric solutions of EV Cnc and AH Cnc revealed a mass ratio of q~0.41 and~0.15 with an inclination of i=42°and87°respectively.These solutions suggest that EV Cnc is probably a semi-detached and AH Cnc is a deep low-mass ratio contact binary.The study of O-C variation analysis indicates that for both systems,the period is increasing which suggests the mass transfer is occurring from secondary to primary.In the case of AH Cnc and based on simulations by randomly varying the time of minima to fit the LITE solution,we noted the third body orbital period to be around P_(3)=26.82±2.54 yr,which is different from earlier reported values and conclude that future observations are required to confirm this scenario.We compare these two systems with other similar contact binaries to get an estimate of the final configuration of the respective systems.
基金K.S.acknowledges the financial support from the Indian Space Research Organisation(ISRO),Government of India。
文摘Understanding the variation of lags with respect to the X-ray flux is important to explore the geometry of the inner region of the accretion disk in AGNs.We performed frequency-lag,energy–lag and spectral studies for two sets of observations,in order to investigate the variations in lags with respect to X-ray flux in the AGN source Mrk 704 using the XMM-Newton observatory.We divided one of the light curves into two sections which were noticed to exhibit a flux variation.The frequency-lag spectra in different energy domains revealed that reverberation(soft)lags varied along with the flux.For the first time,we show that the blurred reflection model can consistently explain the soft excess observed in the X-ray spectra for this source.The fluxes of soft(i.e.,reflection)and hard components were noted to vary by~18%and~9%respectively,across the sections.The soft lag amplitude was found to be larger at the high flux state than the amplitude at the low flux state.Most importantly,we found that both frequency-lag and energy–lag spectra do not display significant variation between two observational data sets despite a flux variation of 43%.This phenomenon cannot be explained by the reflection model because the soft lag amplitudes must be larger in the high flux state.The probable scenario is that,in the low flux state,the obscuring cloud delays the reflected soft photons which increases the soft lag amplitude.
基金the Core Research Grant of SERB,India for the financial support。
文摘Marginal contact binary systems are an important class of binary systems in exploited by astronomers to understand various astrophysical phenomena as they bridge both semi-detached and overcontact stages.We studied the photometric data of CW Aqr using the JCB 1.3 m telescope(JCBT),Kepler,and TESS to understand the period variations and constrain the light curve solutions.We noted that the period of CW Aqr is increasing with a mass transfer rate of m=7.53×10^(-8)M_(⊙)yr^(-1)from the secondary to the primary component.We also ascertained cyclic deviations along with a parabolic trend in the O-C diagram.The residuals displayed a sinusoidal trend which was fitted with an LTTE,indicating the presence of a third body with an orbital period of P_(3)~10 yr and e=0.10.We fitted the JCBT,Kepler,and TESS photometric normalized light curves and noted the mass ratio to be q~0.32 for both contact and semi-detached configurations.We identified a temperature difference between the primary and secondary components of~2500 K.No activity signatures were found in the observed light curves which were also evident from the Hαline studies where the filled-in effect was not seen.Overall our study suggests that CW Aqr is a marginal contact binary with a low mass ratio evolving toward a semi-detached configuration.However,it may merge if the period increases due to ongoing mass transfer accompanied by a lowering in the mass ratio and later oscillate back to the period-decreasing trend due to angular momentum loss over a few cycles of thermal relaxation oscillations followed by instability.
