Variations in solar shortwave radiation in the solar activity cycle as measured by the <Emphasis Type="Italic">CORONAS</Emphasis> satellites

The CORONAS-I and CORONAS-F data on variations in the ionizing shortwave ultraviolet (UV) solar radiation (EUV radiation) at wavelengths of less than 130 nm and near the H Lyman-alpha line are presented. The CORONAS-I data refer to the period close to solar minimum (the index F _10.7 = 80?100), and the CORONAS-F measurements were held close to solar maximum (F_10.7 = 140?280). The UV data are compared to those from the UARS and SOHO satellites and to the results obtained from the ionospheric measurements of ionosphere critical frequencies.     

Optimization of the interplanetary energetic proton flux database and its application in modeling radiation conditions

The dissimilarity of the results of solar and galactic proton flux measurements made on different spacecraft is pointed out. It is caused, in addition to instrument errors, by differences in the temporal and spatial conditions of the measurements. We suggest using statistical analysis of proton fluences calculated for different long time intervals, from half a year to 10 years, for the optimization of the interplanetary proton database. An example of such analysis is presented and a probabilistic model of total proton fluences at the Earth’s orbit outside the magnetosphere, constructed using the analysis, is described. A formalized method for separating proton fluxes in solar proton events from protons of galactic cosmic rays is suggested. A conclusion is made that sources of cosmic ray protons with energies of less than 4 MeV should be examined in more detail.     

The supernova trigger for formation of the solar system

It is suggested that the explosion of a Type II supernova triggered the collapse of a nearby interstellar cloud and led to the formation of the solar system. Estimates of the abundances resulting from nuclear processing of the supernova ejecta are presented. It appears promising that nucleosynthesis in this single supernova event can account for most isotopic anomalies and traces of extinct radioactivities in solar system material.     

地基雷达技术及其在太阳系天体探测中的应用

人类利用雷达波进行天文研究距今已有40多年历史了.它是一种发射雷达波到目标天体,通过分析其回波特性来进行天文探测的技术.该文从地基雷达在太阳系天体探测中的应用出发,分析了地基雷达相比其他探测手段的优点;介绍了地基雷达的基本工作原理;给出了近年来地基雷达的发展情况和探测成果;最后从现有条件出发,探讨了我国开展地基雷达探测的设想.     

X-rays from Venus observed with Chandra

X-ray observations of Venus are so challenging that the first detection of Venusian X-rays succeeded only in January 2001, with the Chandra satellite. The X-rays from Venus were found to result from fluorescent scattering of solar X-rays in the Venusian thermosphere. An additional component, caused by charge exchange of highly charged heavy ions in the solar wind with atoms in the Venusian exosphere, was suspected, but could not be unambiguously detected. This was hampered by the fact that the observation occurred during solar maximum, when the solar X-ray flux is highest. In order to investigate the presence of an additional charge exchange component, Venus was observed again in March 2006 and October 2007 with Chandra, taking advantage of the fact that the solar X-ray flux had decreased considerably on its way to solar minimum. In fact, these subsequent observations were able to show that also the Venusian exosphere is emitting X-rays, due to its interaction with the solar wind. Here an overview of all the existing X-ray observations of Venus is presented, including first results from the most recent one, which took place after the arrival of Venus Express, providing the first ever opportunity to combine a remote X-ray observation of a planetary exosphere with simultaneous in situ measurements of the solar wind.     

Gravity Anomaly During the Mohe Total Solar Eclipse and New Constraint on Gravitational Shielding Parameter

By using a high-precision LaCoste-Romberg gravimeter, continuous and precise measurements were carried out during the March 9, 1997 total solar eclipse in Mohe region in Northeast China. The gravity variations were digitally recorded during the total solar eclipse so as to investigate the possible anomaly of the Sun and the Moon's gravitational fields on the Earth. After the careful processing and analysis of the observed data, no significant anomaly during the very solar eclipse was found. However, there are two ‘gravity anomaly valleys’ with near symmetrical decrease of about 6 ∼ 7 μg at the first contact and the last contact. This is the anomaly phenomenon observed and reported for the first time in the literature. This paper is intended to explain the observed anomaly by conducting the tilt experiment due to the thermal stress and temperature change in the solar eclipse. A new constraint limit on gravitational shielding is thus obtained. Some analysis and discussions are presented although further studies and research are highly needed. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the longitudinal distribution of the solar surges

After re-examination of data presented by Verma (1984), some misuse of solar parameteres published in Solar Geophysical Data is presented. Consequently some conclusions made by Verma (1984, 1986) on about the longitudinal distribution of cool solar surges based on these misuses are discussed.     

Helioseismological constraint on solar axion emission

Helioseismological sound-speed profiles severely constrain possible deviations from standard solar models, allowing us to derive new limits on anomalous solar energy losses by the Primakoff emission of axions. For an axion-photon coupling g_ay 5 × 10⁻¹⁰ GeV⁻¹, the solar model is almost indistinguishable from the standard case, while g_ay 10 × 10⁻¹⁰ GeV⁻¹ is probably excluded, corresponding to an axion luminosity of about 0.20 L. This constraint on g_ay is much weaker than the well-known globular-cluster limit, but about a factor of 3 more restrictive than previous solar limits. Our result is primarily of interest to the large number of current or proposed search experiments for solar axions because our limit defines the maximum g_ay for which it is self-consistent to use a standard solar model to calculate the axion luminosity.     

Solar protons in the Earth’s magnetosphere from riometric and satellite data during magnetic storms in October 2003

The fluxes and penetration boundaries of solar energetic particles on the CORONAS-F satellite during October 2003 superstorms are compared with the riometric absorption measurements on a worldwide network of riometers. The dynamics of the polar cap boundaries is investigated at various phases of magnetic storms. The dependence of absorption on time of the day and on solar proton spectrum is calculated at various phases of a solar energetic particle event.     

太阳表面米粒结构观测对比度分析

分析以观测系统焦面上和探测器测到的太阳表面米粒结构的对比度与观测系统口径，大气湍流相干长度以及系统探测灵敏度的关系，给出了不同口径，不同大气湍流相干长度以及不同系统探测灵敏度时的米粒结构对比值计算结果，此外还给出了实验结果。     

SOHO, Yohkoh, Ulysses and Trace: The four solar missions in perspective, and available resources

Four solar observing spacecraft, now in operation, have obtained and continue to obtain data during the late phase of solar cycle 22 and hopefully most of cycle 23. The data are available for scientific analysis, practically in an unrestricted manner. A large pool of software suited for the processing and to help programming any data analysis is freely available. An almost random list of results that are being obtained with this data is presented as an example of what can be done by analysing the data from these spacecraft, either alone or combining results among them, with ground observatories, or with other spacecraft, such as those that measure particles and fields in interplanetary space or in geospace, to study solar physics or solar-terrestrial relations. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the E-W asymmetry and the generation of ESP events

Observations of energetic-ion intensity enhancements (E 290 keV) associated with solar flare generated shock waves (solar flare ESP events), obtained during nearly a decade by the APL/JHU instruments on board the Earth orbiters IMP-7 and 8, are incorporated in this work in order to examine the role of the heliolongitude depended large scale shock morphology with relation to the upstream interplanetary magnetic field in the formation of these ESP events. It is shown that a clear east-west solar hemisphere asymmetry is present in the distribution of the ESP relative intensity enhancements with respect to the heliolongitudes of the shock wave source-flare sites. The large ion-intensity enhancements superimposed on the ambient solar flare ion population are preferentially associated with solar flare sites located to the east of the spacecraft meridian, whereas on the average only weak ESP events are associated with solar flare sites to the west of the spacecraft meridian. The observed asymmetry and its implications on the dominant processes for the generation of the solar flare ESP events are discussed on the basis of the presented extensive survey.     

On the long-period variations and magnitude of the solar neutrino flux

We analyze the solar neutrino flux fluctuations using data from the Homestake, GALLEX, GNO, SAGE, and Super Kamiokande experiments. Spectral analysis and direct quantitative estimations show that the quasi-five-year periodicity is the most stable neutrino flux variation. Revised mean solar neutrino fluxes are presented. These are used to estimate the observed pp flux of the solar electron neutrinos near the Earth. We consider two alternative explanations for the origin of the variable component of the solar neutrino deficit.     

Probing the interior of asteroids and comets using radio reflection tomography

Abstract— Asteroids and comets are of great scientific interest: their interior structure and composition, which are poorly known, provide information about conditions and processes that occurred during the early stages of solar system development. They are also of interest for social and economic reasons. Their proximity to Earth and abundance in the solar system make them potential sources of raw materials as well as a threat, as evidenced by past catastrophic impacts. Information on their composition and structure is therefore important to assess both the potential benefit of these objects and mitigate the potential risk they pose. This paper describes the use of radio reflection tomography for studying the interiors of asteroids and comets. We discuss technical issues regarding benefits and challenges of implementing a radio reflection tomography instrument and present potential solutions. This paper addresses a range of topics including (1) data collection scenarios, (2) data processing and inversion, and (3) instrument implementation. A “strawman” instrument capable of imaging the full interior of an asteroid or a comet with dimensions of a few kilometers is presented. Such an instrument can play a significant role in studying the near‐Earth objects, both for scientific and socio‐economic purposes.     

Planetary ENA Imaging: Venus and a comparison with Mars

We present simulated images of energetic neutral atoms (ENAs) produced in charge exchange collisions between solar wind protons and neutral atoms in the exosphere of Venus, and make a comparison with earlier results for Mars. The images are found to be dominated by two local maxima. One produced by charge exchange collisions in the solar wind, upstream of the bow shock, and the other close to the dayside ionopause. The simulated ENA fluxes at Venus are lower than those obtained in similar simulations of ENA images at Mars at solar minimum conditions, and close to the fluxes at Mars at solar maximum. Our numerical study shows that the ENA flux decreases with an increasing ionopause altitude. The influence of the Venus nighttime hydrogen bulge on the ENA emission is small.     

Solar corona photometry by electropolarimetric and CCD observations during the eclipse of July 11, 1991

The observational data of the solar corona obtained during the solar eclipse of July 11, 1993, using both a electropolarimeter (EP) and a CCD matrix were processed. Using these data the photometry of the solar corona was carried out. The results of EP data were compared with those of the CCD data. It must be noticed here that the CCD data give us only the characteristics of the inner corona, while the EP data show the features of both the inner and the middle corona up to 4 solar radii. The standard flattening index ϵ was evaluated from both data. The dependence of ϵ on the distance from the solar limb was investigated. Three-dimensional images of the coronal intensity distribution for different spectral lines are shown. Isophotes in Na and Ca lines with unusual features are plotted. Based on these data some ideas and conclusions on the type of the solar corona and the physical conditions in it are presented.     

基于支持向量机的太阳磁场活动区极性反转线位置的探测

太阳磁场的极性反转线(Polarity Inversion Line, PIL)是研究太阳活动、分析太阳磁场结构演变和预测太阳耀斑最重要的日面特征之一.磁场极性反转的位置是太阳耀斑和暗条可能出现的位置."先进天基太阳天文台(ASO-S)"是中国首颗空间太阳专用观测卫星,其搭载的"全日面矢量磁像仪(Full-Disk Vector Magnetograph, FMG)"主要任务是探测高空间、高时间分辨率的全日面矢量磁场.为了提高观测数据使用效率、快速监测太阳活动水平、提高太阳耀斑与日冕物质抛射的预报水平以及更好地服务于FMG数据处理与分析系统,采用了图像自动识别与处理技术,更加精确有效地检测极性反转线.从支持向量机(Support Vector Machine, SVM)的模型出发,将极性反转线位置的探测问题转化为一个模式识别中的二分类问题,提出了一种基于支持向量机的极性反转线检测算法,自动探测与识别太阳动力学天文台(Solar Dynamics Observatory, SDO)日震和磁成像仪(Helioseismic and Magnetic Imager, HMI)磁图的极性反转线位置.与现有算法的对比结果表明,此算法可以精确直观地检测太阳活动区的极性反转线.     

Brightness temperatures of the quiet sun and new moon at the 6 mm wavelength

Absolute brightness temperatures and brightness temperature ratios of a quiet region near the center of the solar disk and the central region of the new moon were measured simultaneously at the 6 mm wavelength. The measured quiet sun/new moon brightness temperature ratios and reported central brightness temperatures of the new moon confirm the measured brightness temperature of the quiet sun at the 6 mm wavelength.Reported central brightness temperatures of the new moon are tabulated and graphed as a function of frequency and wavelength. The equation of a linear regression line for the reported measurements is given for estimating the brightness temperature of the new moon at any millimeter wavelength. Estimated brightness temperatures of the new moon and measured quiet sun/new moon ratios are used to estimate solar brightness temperatures at several millimeter wavelengths. The solar brightness temperatures, the regression line, and the Van de Hulst theoretical model are presented graphically as a function of frequency and wavelength. The regression line equation is given for estimating solar brightness temperatures at any wavelength in the 6 to 1 mm wavelength interval and is solved for the wavelength of the measured ratios.Reported solar brightness temperatures in the millimeter wavelength region are tabulated. The measured temperatures in the 6 to 1 mm wavelength interval and a linear regression line are presented graphically as a function of frequency and wavelength. The regression line equation is given and solved for the solar brightness temperatures at the 6 mm wavelength.This work supported by the U.S. Air Force under Contract No. F04701-69-C-0066.     

关于太阳射电快速活动真伪信号识别问题

本文列举了云南天文台四波段太阳射电实测中得到的几种干扰实例及确认的太阳快速信号，在认识到太阳射电和干扰信号十分相似的基础上，探讨如何识别真伪信号问题。     

Probing the Fundamental Physics of the Solar Corona with Lunar Solar Occultation Observations

Imaging and spectroscopy of the solar corona, coupled with polarimetry, are the only tools available at present to capture signatures of physical processes responsible for coronal heating and solar wind acceleration within the first few solar radii above the solar limb. With the recent advent of improved detector technology and image processing techniques, broad-band white light and narrow-band multi-wavelength observations of coronal forbidden lines, made during total solar eclipses, have started to yield new views about the thermodynamic and magnetic properties of coronal structures. This paper outlines these unique capabilities, which until present, have been feasible primarily with observations during natural total solar eclipses. This work also draws attention to the exciting possibility of greatly increasing the frequency and duration of solar eclipse observations with Moon orbiting observatories utilizing lunar limb occultation of the solar disk for coronal measurements.