We present observations of the active M-dwarf binary AT Mic(dM4.5e+dM4.5e)obtained with the orbital observatory Astro Sat.During 20 ks of observations,in the far-ultraviolet(130-180 nm)and soft X-ray(0.3-7 keV)spectra...We present observations of the active M-dwarf binary AT Mic(dM4.5e+dM4.5e)obtained with the orbital observatory Astro Sat.During 20 ks of observations,in the far-ultraviolet(130-180 nm)and soft X-ray(0.3-7 keV)spectral ranges,we detected both quiescent emission and at least five flares on different components of the binary.The X-ray flares were typically longer than and delayed(by 5-6 minutes)with respect to their ultraviolet counterparts,in agreement with the Neupert effect.Using X-ray spectral fits,we estimated the parameters of the emitting plasma.The results indicate the presence of a hot multi-thermal corona with average temperatures in the range of~7-15 MK and emission measure of~(2.9-4.5)×10^(52)cm^(-3);both the temperature and the emission measure increased during the flares.The estimated abundance of heavy elements in the corona of AT Mic is considerably lower than at the Sun(~0.18-0.34 of the solar photospheric value);the coronal abundance increased during the flares due to chromospheric evaporation.The detected flares had the energies of~10^(31)-10^(32)erg;the energy-duration relations indicate the presence of magnetic fields stronger than in typical solar flares.展开更多
In this study,experiments were performed at bremsstrahlung end-point energies of 10-23 MeV with the beam from the MT-25 microtron using theγ-activation technique.The experimental values of relative yields were compar...In this study,experiments were performed at bremsstrahlung end-point energies of 10-23 MeV with the beam from the MT-25 microtron using theγ-activation technique.The experimental values of relative yields were compared with theoretical results obtained on the basis of TALYS with the standard parameters and the combined model of photonucleon reactions.Including isospin splitting in the combined model of photonucleon reactions allows describing experimental data on reactions with proton escape in the energy range from 10 to 23 MeV.Therefore,taking into account isospin splitting is necessary for a correct description of the decay of the giant dipole resonance.展开更多
Relative yields were measured in the 40−130 MeV bremsstrahlung induced reactions of ^(59)Co.The experiments were performed with the beam from the electron linear accelerator LINAC-200 using the activation and off-line...Relative yields were measured in the 40−130 MeV bremsstrahlung induced reactions of ^(59)Co.The experiments were performed with the beam from the electron linear accelerator LINAC-200 using the activation and off-lineγ-ray spectrometric techniques.The bremsstrahlung photon flux was calculated with the Geant4 program.The cross sections were calculated by using the computer code TALYS-1.96 with different models and were found to be in good agreement with the experimental data.展开更多
基金supported by the BRICS Multilateral Research and Development Projects-2016(DST/MRCK/BRICS/Pilot Call1/Superflares/2017)the project“Superflares on stars and the Sun,”the Russian Foundation for Basic Research under Grant 17-52-80064+1 种基金the Ministry of Science and Higher Education of the Russian Federationsupported by the Research Council of Norway through its Centres of Excellence scheme(project No.262622)。
文摘We present observations of the active M-dwarf binary AT Mic(dM4.5e+dM4.5e)obtained with the orbital observatory Astro Sat.During 20 ks of observations,in the far-ultraviolet(130-180 nm)and soft X-ray(0.3-7 keV)spectral ranges,we detected both quiescent emission and at least five flares on different components of the binary.The X-ray flares were typically longer than and delayed(by 5-6 minutes)with respect to their ultraviolet counterparts,in agreement with the Neupert effect.Using X-ray spectral fits,we estimated the parameters of the emitting plasma.The results indicate the presence of a hot multi-thermal corona with average temperatures in the range of~7-15 MK and emission measure of~(2.9-4.5)×10^(52)cm^(-3);both the temperature and the emission measure increased during the flares.The estimated abundance of heavy elements in the corona of AT Mic is considerably lower than at the Sun(~0.18-0.34 of the solar photospheric value);the coronal abundance increased during the flares due to chromospheric evaporation.The detected flares had the energies of~10^(31)-10^(32)erg;the energy-duration relations indicate the presence of magnetic fields stronger than in typical solar flares.
文摘In this study,experiments were performed at bremsstrahlung end-point energies of 10-23 MeV with the beam from the MT-25 microtron using theγ-activation technique.The experimental values of relative yields were compared with theoretical results obtained on the basis of TALYS with the standard parameters and the combined model of photonucleon reactions.Including isospin splitting in the combined model of photonucleon reactions allows describing experimental data on reactions with proton escape in the energy range from 10 to 23 MeV.Therefore,taking into account isospin splitting is necessary for a correct description of the decay of the giant dipole resonance.
基金Supported in part by the Ministry of Science and Higher Education of the Russian Federation (075-15-2021-1360)by the project of the National Center for Physics and Mathematics (NCPM)No.6“Nuclear and Radiation Physics,”direction 6.5.1。
文摘Relative yields were measured in the 40−130 MeV bremsstrahlung induced reactions of ^(59)Co.The experiments were performed with the beam from the electron linear accelerator LINAC-200 using the activation and off-lineγ-ray spectrometric techniques.The bremsstrahlung photon flux was calculated with the Geant4 program.The cross sections were calculated by using the computer code TALYS-1.96 with different models and were found to be in good agreement with the experimental data.
