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 measurement of positions and sizes of radio sources in observations is important for un- derstanding of the flare evolution. For the first time, solar radio spectral fine structures in an M6.5 flare that occurred ...The measurement of positions and sizes of radio sources in observations is important for un- derstanding of the flare evolution. For the first time, solar radio spectral fine structures in an M6.5 flare that occurred on 2013 April 11 were observed simultaneously by several radio instruments at four different observatories： Chinese Solar Broadband Radio Spectrometer at Huairou （SBRS/Huairou）, Ondrejov Radio Spectrograph in the Czech Republic （ORSC/Ondrejov）, Badary Broadband Microwave Spectropolarimeter （BMS/Irkutsk）, and spectrograph/IZMIRAN （Moscow, Troitsk）. The fine structures included microwave zebra patterns （ZPs）, fast pulsations and fiber bursts. They were observed during the flare brightening lo- cated at the tops of a loop arcade as shown in images taken by the extreme ultraviolet （EUV） telescope onboard NASA＇s satellite Solar Dynamics Observatory （SDO）. The flare occurred at 06：58-07：26 UT in solar active region NOAA 11719 located close to the solar disk center. ZPs appeared near high frequency boundaries of the pulsations, and their spectra observed in Huairou and Ondrejov agreed with each other in terms of details. At the beginning of the flare＇s impulsive phase, a strong narrowband ZP burst occurred with a moderate left-handed circular polarization. Then a series of pulsations and ZPs were observed in almost unpolarized emission. After 07：00 UT a ZP appeared with a moderate right-handed polarization. In the flare decay phase （at about 07：25 UT）, ZPs and fiber bursts become strongly right-hand polarized. BMS/Irkutsk spectral observations indicated that the background emission showed a left-handed circular polarization （similar to SBRS/Huairou spectra around 3 GHz）. However, the fine structure appeared in the right-handed polarization. The dynamics of the polarization was associated with the motion of the flare ex- citer, which was observed in EUV images at 171 A and 131 A by the SDO Atmospheric Imaging Assembly （AIA）. Combining magnetograms observed by the SDO Helioseismic and Magnetic Imager （HMI） with the homologous assumption of EUV flare brightenings and ZP bursts, we deduced that the observed ZPs correspond to the ordinary radio emission mode. However, future analysis needs to verify the assumption that zebra radio sources are really related to a closed magnetic loop, and are located at lower heights in the solar atmosphere than the source of pulsations.展开更多
The two-stream instability is common, responsible for many observed phe- nomena in nature, especially the interaction of jets of various origins with the back- ground plasma （e.g. extragalactic jet interacting with t...The two-stream instability is common, responsible for many observed phe- nomena in nature, especially the interaction of jets of various origins with the back- ground plasma （e.g. extragalactic jet interacting with the cosmic background）. The dispersion relation that does not consider magnetic fields is described by the well- known Buneman relation. In 2011, Bohata, Bren and Kulhanek derived the relation for the two-stream instability without the cold limit, with the general orientation of a magnetic field, and arbitrary stream directions. The maximum value of the imaginary part of the individual dispersion branches ωn（k） is of interest from a physical point of view. It represents the instability growth rate which is responsible for the onset of turbulence mode and subsequent reconnection on the scale of the ion radius accom- panied by a strong plasma thermalization. The paper presented here is focused on the non-relativistic instability growth rate and its dependence on various input parameters, such as magnitude and direction of magnetic field, sound velocity, plasma frequency of the jet and direction of the wave vector during the jet - intergalactic medium in- teraction. The results are presented in plots and can be used for determination of the plasma parameter values close to which the strong energy transfer and thermalization between the jet and the background plasma occur.展开更多
Advances in the technology of astronomical spectra acquisition have resulted in an enormous amount of data available in world-wide telescope archives. It is no longer feasible to analyze them using classical approache...Advances in the technology of astronomical spectra acquisition have resulted in an enormous amount of data available in world-wide telescope archives. It is no longer feasible to analyze them using classical approaches, so a new astronomical discipline,astroinformatics, has emerged. We describe the initial experiments in the investigation of spectral line profiles of emission line stars using machine learning with attempt to automatically identify Be and B[e] stars spectra in large archives and classify their types in an automatic manner. Due to the size of spectra collections, the dimension reduction techniques based on wavelet transformation are studied as well. The result clearly justifies that machine learning is able to distinguish different shapes of line profiles even after drastic dimension reduction.展开更多
This paper presents overview of new features so far prepared for new version of spectral analysis tool SPLAT-VO that allows to retrieve a large amount of spectra(and other data) based on its characteristics by detaile...This paper presents overview of new features so far prepared for new version of spectral analysis tool SPLAT-VO that allows to retrieve a large amount of spectra(and other data) based on its characteristics by detailed querying a virtual observatory s resources. The overview is focused on enhancements of user experience, work with simple application messaging protocol(SAMP) and other interoperability that improves work with global list of spectra, plot window and analysis menu.展开更多
In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry(eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be rep...In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry(eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is expected to be launched in the mid 2020 s.展开更多
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 Chinese Academy of Sciences Visiting Professorship for Senior International Scientists(Grant No.2011T1J20)funded by Chinese Academy of Sciences President’s International Fellowship Initiative(Grant No.2015VMA014)+3 种基金supported by the Russian Foundation for Basic Research(Grants:13-02-00044,13-02-90472,14-02-91157 and 14-02-00367)the National Natural Science Foundation of China(Grant Nos.11273030,11103044,11103039,11221063,11373039 and 113111042)MOST(Grant2011CB811401)the National Major Scientific Equipment R&D Project(ZDYZ 2009-3 and P209/12/00103 GA CR)
文摘The measurement of positions and sizes of radio sources in observations is important for un- derstanding of the flare evolution. For the first time, solar radio spectral fine structures in an M6.5 flare that occurred on 2013 April 11 were observed simultaneously by several radio instruments at four different observatories： Chinese Solar Broadband Radio Spectrometer at Huairou （SBRS/Huairou）, Ondrejov Radio Spectrograph in the Czech Republic （ORSC/Ondrejov）, Badary Broadband Microwave Spectropolarimeter （BMS/Irkutsk）, and spectrograph/IZMIRAN （Moscow, Troitsk）. The fine structures included microwave zebra patterns （ZPs）, fast pulsations and fiber bursts. They were observed during the flare brightening lo- cated at the tops of a loop arcade as shown in images taken by the extreme ultraviolet （EUV） telescope onboard NASA＇s satellite Solar Dynamics Observatory （SDO）. The flare occurred at 06：58-07：26 UT in solar active region NOAA 11719 located close to the solar disk center. ZPs appeared near high frequency boundaries of the pulsations, and their spectra observed in Huairou and Ondrejov agreed with each other in terms of details. At the beginning of the flare＇s impulsive phase, a strong narrowband ZP burst occurred with a moderate left-handed circular polarization. Then a series of pulsations and ZPs were observed in almost unpolarized emission. After 07：00 UT a ZP appeared with a moderate right-handed polarization. In the flare decay phase （at about 07：25 UT）, ZPs and fiber bursts become strongly right-hand polarized. BMS/Irkutsk spectral observations indicated that the background emission showed a left-handed circular polarization （similar to SBRS/Huairou spectra around 3 GHz）. However, the fine structure appeared in the right-handed polarization. The dynamics of the polarization was associated with the motion of the flare ex- citer, which was observed in EUV images at 171 A and 131 A by the SDO Atmospheric Imaging Assembly （AIA）. Combining magnetograms observed by the SDO Helioseismic and Magnetic Imager （HMI） with the homologous assumption of EUV flare brightenings and ZP bursts, we deduced that the observed ZPs correspond to the ordinary radio emission mode. However, future analysis needs to verify the assumption that zebra radio sources are really related to a closed magnetic loop, and are located at lower heights in the solar atmosphere than the source of pulsations.
基金supported by the Czech Technical University in Prague with grants SGS10/266/OHK3/3T/13 (Electric discharges, basic research and application,SGS12/181/OHK3/3T/13 (Plasma instabilities and plasma-particle interactions)by the Grant Agency of the Czech Republic with grant GD205/09/H033 (General relativity and its applications in astrophysics and cosmology)
文摘The two-stream instability is common, responsible for many observed phe- nomena in nature, especially the interaction of jets of various origins with the back- ground plasma （e.g. extragalactic jet interacting with the cosmic background）. The dispersion relation that does not consider magnetic fields is described by the well- known Buneman relation. In 2011, Bohata, Bren and Kulhanek derived the relation for the two-stream instability without the cold limit, with the general orientation of a magnetic field, and arbitrary stream directions. The maximum value of the imaginary part of the individual dispersion branches ωn（k） is of interest from a physical point of view. It represents the instability growth rate which is responsible for the onset of turbulence mode and subsequent reconnection on the scale of the ion radius accom- panied by a strong plasma thermalization. The paper presented here is focused on the non-relativistic instability growth rate and its dependence on various input parameters, such as magnitude and direction of magnetic field, sound velocity, plasma frequency of the jet and direction of the wave vector during the jet - intergalactic medium in- teraction. The results are presented in plots and can be used for determination of the plasma parameter values close to which the strong energy transfer and thermalization between the jet and the background plasma occur.
基金supported by Czech Science Foundation(No.GACR13-08195S)the project Central Register of Research Intentions CEZMSM0021630528 Security-oriented Research in Information Technology,the specific research(No.FIT-S-11-2)+2 种基金the project RVO:67985815the Technological agency of the Czech Republic(TACR)project V3C(No.TE01020415)Grant Agency of the Czech Republic-GACR P103/13/08195S
文摘Advances in the technology of astronomical spectra acquisition have resulted in an enormous amount of data available in world-wide telescope archives. It is no longer feasible to analyze them using classical approaches, so a new astronomical discipline,astroinformatics, has emerged. We describe the initial experiments in the investigation of spectral line profiles of emission line stars using machine learning with attempt to automatically identify Be and B[e] stars spectra in large archives and classify their types in an automatic manner. Due to the size of spectra collections, the dimension reduction techniques based on wavelet transformation are studied as well. The result clearly justifies that machine learning is able to distinguish different shapes of line profiles even after drastic dimension reduction.
基金supported by Agency of the Czech Republic-GACR(No.P103/13/08195S)the Development of Human Resources in Research and Development of Latest Soft Computing Methods and Their Application in Practical Project,Operational Programm Education for Competitiveness(No.CZ.1.07/2.3.00/20.0072)+1 种基金ESF State Budget of the Czech Republic,SGS(No.SP2013/114)VBTechnical University of Ostrava,Czech Republic
文摘This paper presents overview of new features so far prepared for new version of spectral analysis tool SPLAT-VO that allows to retrieve a large amount of spectra(and other data) based on its characteristics by detailed querying a virtual observatory s resources. The overview is focused on enhancements of user experience, work with simple application messaging protocol(SAMP) and other interoperability that improves work with global list of spectra, plot window and analysis menu.
基金support from ERC Starting (Grant No. 639217 CSINEUTRONSTAR)support from a Netherlands Organization for Scientific Research (NWO) Vidi Fellowship+2 种基金suported by the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Global Fellowship (Grant No. 703916)supported in part by the DFG through Grant SFB 1245 and the ERC (Grant No. 307986 STRONGINT)support of the Chinese Academy of Sciences through the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA15020100)
文摘In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry(eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is expected to be launched in the mid 2020 s.
