Abstract The paper presents study the 11-year dynamics of solar activity on the basis of new observational material on coronal holes (CHs) and sunspots in the period from May 13, 2010 to May 13, 2021. We used the Heliophysics Event Knowledgebase (HEK) to obtain information on CHs areas. For 11 years of observations, we processed about 18000 CHs. Slightly more than 8000 are polar, the rest are nonpolar CHs. The statistical volume of the presented material is quite extensive and gives grounds for the study of the dynamics of different types of CHs during the cycle. Our research has shown: in the 24th solar activity cycle, the South led for polar CHs and the North led for nonpolar ones. We established a relationship between the number and area of CHs and the phase of the solar cycle. The number and daily total area of polar CHs increases at the minima of solar activity and decreases at the maximum of the cycle. This is consistent with the general concept of polar CHs as the main source of the solar dipole magnetic field. An asymmetry in both the number and areas of polar coronal holes in the northern and southern hemispheres is observed. It is shown that the areas of nonpolar CHs change quasi-synchronously with sunspot activity, which suggests a physical connection between these two phenomena.
{"title":"11-year dynamics of coronal hole and sunspot areas","authors":"O. Andreeva, V. Abramenko, V. Malashchuk","doi":"10.1515/astro-2022-0005","DOIUrl":"https://doi.org/10.1515/astro-2022-0005","url":null,"abstract":"Abstract The paper presents study the 11-year dynamics of solar activity on the basis of new observational material on coronal holes (CHs) and sunspots in the period from May 13, 2010 to May 13, 2021. We used the Heliophysics Event Knowledgebase (HEK) to obtain information on CHs areas. For 11 years of observations, we processed about 18000 CHs. Slightly more than 8000 are polar, the rest are nonpolar CHs. The statistical volume of the presented material is quite extensive and gives grounds for the study of the dynamics of different types of CHs during the cycle. Our research has shown: in the 24th solar activity cycle, the South led for polar CHs and the North led for nonpolar ones. We established a relationship between the number and area of CHs and the phase of the solar cycle. The number and daily total area of polar CHs increases at the minima of solar activity and decreases at the maximum of the cycle. This is consistent with the general concept of polar CHs as the main source of the solar dipole magnetic field. An asymmetry in both the number and areas of polar coronal holes in the northern and southern hemispheres is observed. It is shown that the areas of nonpolar CHs change quasi-synchronously with sunspot activity, which suggests a physical connection between these two phenomena.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"22 - 26"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44767995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kanrong Liu, Yajie Wang, Baohui Zhang, Hu Liu, Xu Wang, Bin Wei
Abstract This study presented a mathematical description of an arbitrary shape area, and after analyzing the characteristics of the near-polar orbital co-ground trajectory constellation that satisfies the revisit interval constraint, an optimization model of the orbital parameters design of reference satellites in regional coverage constellations was constructed. Then based on the designed area covering the constellation of common ground trajectories, a simple and effective two-pulse maneuvering scheme was adopted for the needs of sudden tasks, and an existing satellite scheduling optimization model using the golden section method to constrain the boundary of substellar point coverage was constructed. Finally, the optimal design of regional coverage constellations and existing satellite dispatches was carried out for the sea areas with the most frequent tropical cyclone activities in the northwest Pacific Ocean, and the simulation results verified the effectiveness of the proposed optimization model and have certain practical use value.
{"title":"Optimization of satellite resource scheduling under regional target coverage conditions","authors":"Kanrong Liu, Yajie Wang, Baohui Zhang, Hu Liu, Xu Wang, Bin Wei","doi":"10.1515/astro-2022-0036","DOIUrl":"https://doi.org/10.1515/astro-2022-0036","url":null,"abstract":"Abstract This study presented a mathematical description of an arbitrary shape area, and after analyzing the characteristics of the near-polar orbital co-ground trajectory constellation that satisfies the revisit interval constraint, an optimization model of the orbital parameters design of reference satellites in regional coverage constellations was constructed. Then based on the designed area covering the constellation of common ground trajectories, a simple and effective two-pulse maneuvering scheme was adopted for the needs of sudden tasks, and an existing satellite scheduling optimization model using the golden section method to constrain the boundary of substellar point coverage was constructed. Finally, the optimal design of regional coverage constellations and existing satellite dispatches was carried out for the sea areas with the most frequent tropical cyclone activities in the northwest Pacific Ocean, and the simulation results verified the effectiveness of the proposed optimization model and have certain practical use value.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"318 - 326"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46570596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract BeiDou navigation satellite system (BDS) receivers on-board cannot give real-time positioning precision in tracking missile and carrier rocket. In this article, the dynamic filtered optimal estimation theory is applied to the highly dynamic on-board BDS ballistic parameter solution, an optimally constrained geometric dilution precision (GDOP) constellation selection strategy is proposed, a mathematical model based on dynamic filtered estimation for the ballistic determination and precision estimation of the on-board BDS is established, and an analysis of the on-board BDS positioning precision is carried out using the observed data. The calculation results show that the dynamic filter positioning algorithm is simple, practical, and reliable, which can effectively suppress and reduce the random errors of ballistic parameters and significantly improve the positioning precision, fully satisfying the needs of high dynamic and high precision navigation and positioning users, and has good application prospects.
{"title":"On-board BDS dynamic filtering ballistic determination and precision evaluation","authors":"Shuyang Zhao, Jia-Yu Chang","doi":"10.1515/astro-2022-0193","DOIUrl":"https://doi.org/10.1515/astro-2022-0193","url":null,"abstract":"Abstract BeiDou navigation satellite system (BDS) receivers on-board cannot give real-time positioning precision in tracking missile and carrier rocket. In this article, the dynamic filtered optimal estimation theory is applied to the highly dynamic on-board BDS ballistic parameter solution, an optimally constrained geometric dilution precision (GDOP) constellation selection strategy is proposed, a mathematical model based on dynamic filtered estimation for the ballistic determination and precision estimation of the on-board BDS is established, and an analysis of the on-board BDS positioning precision is carried out using the observed data. The calculation results show that the dynamic filter positioning algorithm is simple, practical, and reliable, which can effectively suppress and reduce the random errors of ballistic parameters and significantly improve the positioning precision, fully satisfying the needs of high dynamic and high precision navigation and positioning users, and has good application prospects.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"340 - 347"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48048856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The results of observations of selected stars orbiting the central body of our Galaxy, which, according to the latest data, has a mass of about 4 million of solar mass, are considered. Using the methods of observation and processing of binary stars used at the Pulkovo Observatory and the published exact relative positions of the star-central body obtained with the Keck and VLT telescopes, we checked the possibility of determining the preliminary orbits of the above objects in some cases from observations covering sufficient short arc in relation to the turnover period. Examples are the stars S02 and S102 with published positions and the graphical data for S27 and S4711. We attempted to calculate the assumed relativistic effects in accordance with the orbital elements obtained by Pulkovo methods. In this case, the estimates of the O–C errors for these orbits turned out to be comparable with the O–C errors for the orbits published by the Keck and VLT observers, in some cases about several milliarcseconds. The theoretical relativistic parameters also turned out to be of the same order of value with the results of these authors.
{"title":"Checking the possibility of determining the relative orbits of stars rotating around the center body of the Galaxy","authors":"N. A. Shakht, I. Izmailov, D. Gorshanov","doi":"10.1515/astro-2022-0016","DOIUrl":"https://doi.org/10.1515/astro-2022-0016","url":null,"abstract":"Abstract The results of observations of selected stars orbiting the central body of our Galaxy, which, according to the latest data, has a mass of about 4 million of solar mass, are considered. Using the methods of observation and processing of binary stars used at the Pulkovo Observatory and the published exact relative positions of the star-central body obtained with the Keck and VLT telescopes, we checked the possibility of determining the preliminary orbits of the above objects in some cases from observations covering sufficient short arc in relation to the turnover period. Examples are the stars S02 and S102 with published positions and the graphical data for S27 and S4711. We attempted to calculate the assumed relativistic effects in accordance with the orbital elements obtained by Pulkovo methods. In this case, the estimates of the O–C errors for these orbits turned out to be comparable with the O–C errors for the orbits published by the Keck and VLT observers, in some cases about several milliarcseconds. The theoretical relativistic parameters also turned out to be of the same order of value with the results of these authors.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"136 - 142"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48860738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this work, cosmological solutions based on the time-dependent cosmological ( Λ Lambda ) and Newtonian ( G G ) running “constants” in the Bianchi type-I spacetime are investigated vis-à-vis known cosmological data. The observationally known values of Ω m , Ω r {Omega }_{{rm{m}}},{Omega }_{{rm{r}}} and Ω Λ {Omega }_{Lambda } have been used to solve the Einstein field equations for the model and the resulting behaviours of the physical and dynamical quantities, with particular emphasis on late-time cosmology, are discussed. Our analysis indicates that certain choices of the defining model parameters give results consistent with the observed behaviour of the universe, such as accelerated expansion and an early anisotropy that vanishes at late times.
{"title":"The evolution of time-dependent Λ and G in multi-fluid Bianchi type-I cosmological models","authors":"A. H. Alfedeel, Amare Abebe","doi":"10.1515/astro-2022-0027","DOIUrl":"https://doi.org/10.1515/astro-2022-0027","url":null,"abstract":"Abstract In this work, cosmological solutions based on the time-dependent cosmological ( Λ Lambda ) and Newtonian ( G G ) running “constants” in the Bianchi type-I spacetime are investigated vis-à-vis known cosmological data. The observationally known values of Ω m , Ω r {Omega }_{{rm{m}}},{Omega }_{{rm{r}}} and Ω Λ {Omega }_{Lambda } have been used to solve the Einstein field equations for the model and the resulting behaviours of the physical and dynamical quantities, with particular emphasis on late-time cosmology, are discussed. Our analysis indicates that certain choices of the defining model parameters give results consistent with the observed behaviour of the universe, such as accelerated expansion and an early anisotropy that vanishes at late times.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"198 - 204"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48322079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This article is devoted to the discovery of comets at the Vilnius Observatory together with the orbital analysis of dynamically interesting comets, namely 322P. We studied the orbital evolution of comet 322P with and without non-gravitational effects. It turned out that many of the comet’s orbital clones go into and out of retrograde orbits, sometimes repeatedly. The reason for such dramatic changes in the inclination of the orbit is the origin of comet 322P close to mean motion resonance 3:1 with Jupiter, ejecting them from there and, consequently, bringing the clones closer to the terrestrial group of planets. In this way, the clones of comet 322P enter retrograde orbits and reside there several ky to several My.
{"title":"Observational data and orbits of the comets discovered at the Vilnius Observatory in 1980–2006 and the case of the comet 322P","authors":"I. Wlodarczyk, K. Černis","doi":"10.1515/astro-2022-0023","DOIUrl":"https://doi.org/10.1515/astro-2022-0023","url":null,"abstract":"Abstract This article is devoted to the discovery of comets at the Vilnius Observatory together with the orbital analysis of dynamically interesting comets, namely 322P. We studied the orbital evolution of comet 322P with and without non-gravitational effects. It turned out that many of the comet’s orbital clones go into and out of retrograde orbits, sometimes repeatedly. The reason for such dramatic changes in the inclination of the orbit is the origin of comet 322P close to mean motion resonance 3:1 with Jupiter, ejecting them from there and, consequently, bringing the clones closer to the terrestrial group of planets. In this way, the clones of comet 322P enter retrograde orbits and reside there several ky to several My.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"244 - 255"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44606441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract With the development of human space technology, more and more astronauts fly into space. With the rapid development of commercial aerospace, more ordinary people will go to space for sightseeing. However, it should not be ignored that microgravity, space radiation, relative geometry, and orbit of space stations have various effects on the health of astronauts. In recent years, scholars in various countries have made considerable research progress in this field. This article analyzes the research history and current situation of this field, including the individual effects of space radiation, microgravity, orbit, and relative geometry, as well as their comprehensive effects. In addition, various nursing measures have been investigated.
{"title":"Research progress on the effects of microgravity and space radiation on astronauts’ health and nursing measures","authors":"Xinhua Cao","doi":"10.1515/astro-2022-0038","DOIUrl":"https://doi.org/10.1515/astro-2022-0038","url":null,"abstract":"Abstract With the development of human space technology, more and more astronauts fly into space. With the rapid development of commercial aerospace, more ordinary people will go to space for sightseeing. However, it should not be ignored that microgravity, space radiation, relative geometry, and orbit of space stations have various effects on the health of astronauts. In recent years, scholars in various countries have made considerable research progress in this field. This article analyzes the research history and current situation of this field, including the individual effects of space radiation, microgravity, orbit, and relative geometry, as well as their comprehensive effects. In addition, various nursing measures have been investigated.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"300 - 309"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47947993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.51194/vak2021.2022.1.1.054
B. Losovsky
Abstract A characteristic property of pulsars is pulsed periodic radio emission, which has a high stability of periods. Despite the high stability of the emission periods of pulsars, monitoring the time of arrival of pulses (timing) shows the presence of different types of irregularities: variations of residual deviations, changes in the shape of the pulse, switching on and off of radio emission, and rotation discontinuities. Numerous observations of the radio emission of pulsars indicate that they are caused mainly by processes occurring in the pulsar’s magnetosphere. The special interest causes the observations of a pulsar in the Crab Nebula, performed, in particular, at Jodrell Bank and Pushchino Radio Astronomy Observatory of Lebedev Physical Institute. The connection between the scattering of radio pulses and the measure of the pulsar dispersion, which was established earlier in Pushchino together with Jodrell Bank, has been confirmed. The observed variations in the scattering of radio pulses and their partial correlation with the dispersion measure are explained by the eclipse of the pulsar by plasma clouds with electron density fluctuations significantly exceeding the corresponding fluctuations in the interstellar medium. The question of a possible connection between glitches, dispersion measure variations, radio pulses scattering, and gamma-ray flares is discussed.
{"title":"The specifics of pulsar radio emission","authors":"B. Losovsky","doi":"10.51194/vak2021.2022.1.1.054","DOIUrl":"https://doi.org/10.51194/vak2021.2022.1.1.054","url":null,"abstract":"Abstract A characteristic property of pulsars is pulsed periodic radio emission, which has a high stability of periods. Despite the high stability of the emission periods of pulsars, monitoring the time of arrival of pulses (timing) shows the presence of different types of irregularities: variations of residual deviations, changes in the shape of the pulse, switching on and off of radio emission, and rotation discontinuities. Numerous observations of the radio emission of pulsars indicate that they are caused mainly by processes occurring in the pulsar’s magnetosphere. The special interest causes the observations of a pulsar in the Crab Nebula, performed, in particular, at Jodrell Bank and Pushchino Radio Astronomy Observatory of Lebedev Physical Institute. The connection between the scattering of radio pulses and the measure of the pulsar dispersion, which was established earlier in Pushchino together with Jodrell Bank, has been confirmed. The observed variations in the scattering of radio pulses and their partial correlation with the dispersion measure are explained by the eclipse of the pulsar by plasma clouds with electron density fluctuations significantly exceeding the corresponding fluctuations in the interstellar medium. The question of a possible connection between glitches, dispersion measure variations, radio pulses scattering, and gamma-ray flares is discussed.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"189 - 197"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42945439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The observed primordial energy release of solar flare in the corona is explained by the mechanism of S. I. Syrovatskii, according to which the flare energy is accumulated in the current sheet. The flare release of the current sheet energy causes the observed manifestations of the flare, which are explained by the electrodynamical model of a solar flare proposed by I. M. Podgorny. According to this model, hard X-ray beam radiation on the solar surface is explained by the acceleration of electrons in field aligned currents caused by the Hall electric field in the current sheet. The study of the flare mechanism is impossible without performing magnetohydrodynamic (MHD) simulations above a real active region (AR), in which the calculation begins several days before the appearance of flares. When setting the problem, no assumptions were made about the flare mechanism. An absolutely implicit finite-difference scheme, conservative with respect to the magnetic flux, has been developed, which is implemented in the PERESVET code. MHD simulation in the real scale of time can only be carried out, thanks to parallel computations using compute unified device architecture (CUDA) technology. Methods have been developed that made it possible to stabilize the numerical instability arising near the boundary of the region. Calculation above AR 10365 for low viscosities ( Rm = 1 0 9 {rm{Rm}}=1{0}^{9} , Re = 1 0 7 {rm{Re}}=1{0}^{7} , ν Art Phoosphere = ν Magn Art Phoosphere = 1 0 − 4 {nu }_{text{Art Phoosphere}}={nu }_{text{Magn Art Phoosphere}}=1{0}^{-4} ) showed the appearance of a singular X-type line, in the vicinity of which a current sheet with accumulated magnetic energy for a flare can form. Also, by means of MHD simulation the appearance of singular lines above a real AR is shown, in which the magnetic field is a superposition of an X-type field and a diverging magnetic field. In such a superposition of configurations, even if the diverging field predominates, the formation of a current sheet is possible, which can explain the appearance of a flare of not very high power. The coincidence of the position of the source of the flare thermal X-ray radiation with the places of appearance of the current sheets confirms the mechanism of the solar flare, based on the accumulation of energy in the magnetic field of the current sheet.
摘要用S. I. Syrovatskii机制解释了观测到的太阳耀斑在日冕中的原始能量释放，根据该机制，耀斑能量是在电流片中积累的。耀斑释放的电流片能量引起了观测到的耀斑现象，用Podgorny提出的太阳耀斑电动力学模型解释了这一现象。根据该模型，太阳表面的硬x射线束辐射可以用电流片中的霍尔电场引起的场向电流中电子的加速来解释。耀斑机制的研究不可能在实际活动区域(AR)上进行磁流体动力学(MHD)模拟，在实际活动区域(AR)中，计算在耀斑出现前几天开始。在设置问题时，没有对耀斑机制做任何假设。开发了一种绝对隐式的有限差分格式，该格式对磁通量是保守的，并在PERESVET程序中实现。MHD仿真只能在真实时间尺度下进行，这要归功于使用CUDA技术的并行计算。已经开发了一些方法，使在区域边界附近产生的数值不稳定性趋于稳定成为可能。在ar10365上计算低粘度(Rm =1 0 9 { Rm {Rm}}=1{0}^{9}， Re =1 0 7 { Rm {Re}}=1{0}^{7}， ν Art photomsphere = ν Magn Art photomsphere =1 0−4 {nu}_{text{Art photomsphere}}={nu}_{text{Magn Art photomsphere}}=1{0}^{-4})，显示了一个奇异的x型线的出现，在其附近可以形成一个具有耀斑积累的磁能的电流片。此外，通过MHD模拟显示了真实AR上方奇异线的出现，其中磁场是x型磁场和发散磁场的叠加。在这样的叠加态中，即使发散场占主导地位，电流片的形成也是可能的，这可以解释功率不是很高的耀斑的出现。耀斑热x射线辐射源的位置与电流片出现的位置的重合，证实了基于电流片磁场能量积累的太阳耀斑的机制。
{"title":"Investigation of the mechanism of a solar flare by means of MHD simulations above the active region in real scale of time: The choice of parameters and the appearance of a flare situation","authors":"A. Podgorny, I. Podgorny, A. Borisenko","doi":"10.1515/astro-2022-0006","DOIUrl":"https://doi.org/10.1515/astro-2022-0006","url":null,"abstract":"Abstract The observed primordial energy release of solar flare in the corona is explained by the mechanism of S. I. Syrovatskii, according to which the flare energy is accumulated in the current sheet. The flare release of the current sheet energy causes the observed manifestations of the flare, which are explained by the electrodynamical model of a solar flare proposed by I. M. Podgorny. According to this model, hard X-ray beam radiation on the solar surface is explained by the acceleration of electrons in field aligned currents caused by the Hall electric field in the current sheet. The study of the flare mechanism is impossible without performing magnetohydrodynamic (MHD) simulations above a real active region (AR), in which the calculation begins several days before the appearance of flares. When setting the problem, no assumptions were made about the flare mechanism. An absolutely implicit finite-difference scheme, conservative with respect to the magnetic flux, has been developed, which is implemented in the PERESVET code. MHD simulation in the real scale of time can only be carried out, thanks to parallel computations using compute unified device architecture (CUDA) technology. Methods have been developed that made it possible to stabilize the numerical instability arising near the boundary of the region. Calculation above AR 10365 for low viscosities ( Rm = 1 0 9 {rm{Rm}}=1{0}^{9} , Re = 1 0 7 {rm{Re}}=1{0}^{7} , ν Art Phoosphere = ν Magn Art Phoosphere = 1 0 − 4 {nu }_{text{Art Phoosphere}}={nu }_{text{Magn Art Phoosphere}}=1{0}^{-4} ) showed the appearance of a singular X-type line, in the vicinity of which a current sheet with accumulated magnetic energy for a flare can form. Also, by means of MHD simulation the appearance of singular lines above a real AR is shown, in which the magnetic field is a superposition of an X-type field and a diverging magnetic field. In such a superposition of configurations, even if the diverging field predominates, the formation of a current sheet is possible, which can explain the appearance of a flare of not very high power. The coincidence of the position of the source of the flare thermal X-ray radiation with the places of appearance of the current sheets confirms the mechanism of the solar flare, based on the accumulation of energy in the magnetic field of the current sheet.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"27 - 37"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48837767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract An integrated ranging and differential one-way range (DOR) signal design is implemented. The design utilizes the regenerative pseudo-noise ranging scheme and one pair of dedicated DOR tones for the deep space United X Band system. To demonstrate its effectiveness, it was applied to China’s Tianwen-1 orbiter and compared with the classic and normal designs. Using the link budget and error analysis methods, the measurement accuracy and communication ability were assessed. Results show that the novel design achieves better performance compared with that of the classic and normal designs. In the applied case, the power efficiency improved by > 30 % gt 30 % , two-way ranging precision improved from 0.50 to 0.09 m, and the two-way Doppler precision improved by 20% compared with those of the classic one. In addition, the spacecraft thermal noise during Delta-DOR measurements was slightly reduced. Owing to the higher downlink residual carrier, the supported telemetry data rate increased by 50%. Compared with the normal one, a higher downlink residual carrier (by 0.35 dB) was achieved by the novel design and resulted in slightly better ranging and Doppler accuracies. The novel design has a good technical foundation and is expected to be adopted in China’s future lunar and deep space explorations.
{"title":"Integrated design of ranging and DOR signal for China's deep space navigation","authors":"De-Zhen Xu, Lei Huang, Shaowu Chen","doi":"10.1515/astro-2022-0200","DOIUrl":"https://doi.org/10.1515/astro-2022-0200","url":null,"abstract":"Abstract An integrated ranging and differential one-way range (DOR) signal design is implemented. The design utilizes the regenerative pseudo-noise ranging scheme and one pair of dedicated DOR tones for the deep space United X Band system. To demonstrate its effectiveness, it was applied to China’s Tianwen-1 orbiter and compared with the classic and normal designs. Using the link budget and error analysis methods, the measurement accuracy and communication ability were assessed. Results show that the novel design achieves better performance compared with that of the classic and normal designs. In the applied case, the power efficiency improved by > 30 % gt 30 % , two-way ranging precision improved from 0.50 to 0.09 m, and the two-way Doppler precision improved by 20% compared with those of the classic one. In addition, the spacecraft thermal noise during Delta-DOR measurements was slightly reduced. Owing to the higher downlink residual carrier, the supported telemetry data rate increased by 50%. Compared with the normal one, a higher downlink residual carrier (by 0.35 dB) was achieved by the novel design and resulted in slightly better ranging and Doppler accuracies. The novel design has a good technical foundation and is expected to be adopted in China’s future lunar and deep space explorations.","PeriodicalId":19514,"journal":{"name":"Open Astronomy","volume":"31 1","pages":"358 - 365"},"PeriodicalIF":0.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45460810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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