A Re-Evaluation of the Abundance of Lutetium in the Sun

Lutetium is one of the few nonvolatile elements whose solar photospheric abundance departs significantly from that derived from CI chondrites. We have applied the Cowan code to compute new oscillator strengths for Luii, and have included a correction for core polarization. The results have been used in a synthesis of the solar spectrum in the vicinity of features at 3397.062 and 6221.72. We find that the majority of the absorption in the ultraviolet feature is due to NH, making it unsuitable for extracting a reliable lutetium abundance. Our best fit to the low-noise Jungfraujoch spectrum for the weak, nine-component hyperfine Luii line at 6221.87 yields an abundance of +0.06 on a scale where log(H) = 12.00. This value is within 0.07 dex of the meteoritic result (+0.13). (These figures reflect the note added in proof below.)     

A Study on the Abundance Distribution of Heavy Elements in Metal-poor Stars by the Parameterization Method

Based on a large amount of observed data of element abundances in metal-poor stars, taking the abundance distribution of heavy elements in the solar system as a standard, and selecting Sr, Ba and Eu as the typical elements of the three nucleosynthetic processes in metal-poor stars, namely the weak sprocess, main s-process and r-process, we have studied the contributions of the three kinds of neutron-capture processes to the abundance distribution of heavy elements in metal-poor stars, with the parameterization method. It is found that the higher the metal abundance, the greater the contributions of the weak s-process and the chief s-process to the abundances of lighter neutron-capture elements. The heavier neutron-capture elements are mainly produced by the r-process and the chief s-process; and that at low metallicity, the abundances of heavy neutron-capture elements are mainly produced by the r-process. In the early Galaxy, the weak s-process has almost no contribution to the element abundance.     

贫金属星重元素丰度分布的参数化研究

基于大量贫金属星元素丰度的观测资料,以太阳系重元素丰度分布为标准,选取Sr、Ba、Eu分别作为贫金属星弱s-过程、主要s-过程、r-过程3种核合成的典型元素,采用参数化方法,分析了不同核合成过程对贫金属星重元素丰度的贡献比例.研究表明:金属丰度越高,弱s-过程、主要s-过程对较轻的中子俘获元素丰度的贡献就越大,较重的中子俘获元素主要由r-过程和主要s-过程产生;金属丰度较低,重中子俘获元素丰度主要由r-过程产生,星系早期弱s-过程对元素丰度几乎没有贡献.     

A Snapshot of the Sun Near Solar Minimum: The Whole Heliosphere Interval

We present an overview of the data and models collected for the Whole Heliosphere Interval, an international campaign to study the three-dimensional solar?Cheliospheric?Cplanetary connected system near solar minimum. The data and models correspond to solar Carrington Rotation 2068 (20 March??C?16 April 2008) extending from below the solar photosphere, through interplanetary space, and down to Earth??s mesosphere. Nearly 200 people participated in aspects of WHI studies, analyzing and interpreting data from nearly 100 instruments and models in order to elucidate the physics of fundamental heliophysical processes. The solar and inner heliospheric data showed structure consistent with the declining phase of the solar cycle. A closely spaced cluster of low-latitude active regions was responsible for an increased level of magnetic activity, while a highly warped current sheet dominated heliospheric structure. The geospace data revealed an unusually high level of activity, driven primarily by the periodic impingement of high-speed streams. The WHI studies traced the solar activity and structure into the heliosphere and geospace, and provided new insight into the nature of the interconnected heliophysical system near solar minimum.     

太阳伽玛射线谱与元素丰度

耀斑伽玛射线谱中色含着作用区太阳大气元素丰度及加速高能粒子元素丰度的重要信息。综述了这一刚刚兴起的伽玛射线谱诊断元素丰度的新领域及其所获得的若干新结果。     

A Statistical Model for Predicting the Average Abundance Patterns of Heavier Elements in Metal-Poor Stars

We have collected nearly all the available observed data of the elements from Ba to Dy in halo and disk stars in the metallicity range -4.0 <[Fe/H]< 0.5. Based on the observed data of Ba and Eu, we evaluated the least-squares regressions of [Ba/Fe] on [Fe/H], and [Eu/H] on [Ba/H]. Assuming that the heavy elements (heavier than Ba) are produced by a combination of the main components of s- and r-processes in metal-poor stars, and choosing Ba and Eu as respective representative elements of the main s- and the main r-processes, a statistical model for predicting the Galactic chemical evolution of the heavy elements is presented. With this model, we calculate the mean abundance trends of the heavy elements La, Ce, Pr, Nd, Sm, and Dy with the metallicity. We compare our results with the observed data at various metallicities, showing that the predicted trends are in good agreement with the observed trends, at least for the metallicity range [Fe/H]> -2.5. Finally, we discuss our results and deduce some importa     

关于氘的原初丰度

本文用均匀的化学演化模型讨论了银河系中氘和氦３的丰度演化．发现当采用大质量恒星占比例较低的初始质量函数,并考虑到气体内落的影响,原初氘丰度ｙ２ｐ～（２－３）×１０－５,将能与太阳系附近的实测相洽．这结果大体与类星体吸收云中氘丰度实测的低值相一致,而吸收云中测得的氘丰度的高值却与星系化学演化模型不一致．此外讨论了这结果可能给大爆炸核合成理论的检验带来的问题．     

恒星锂丰度研究进展

锂是少数几种在大中生成的元素之一,研究锂丰度对于探讨各种元素核合成理论以及星系的早期化学演化规律都具有十分重要的意义,阐述了有关恒星（类太阳星,晕族恒星和主序前得）及星团锂丰度的新近观测结果。介绍了在锂的核合成理论研究方面非局部热动平衡效应的影响及锂在恒星演化中的衰竭机制等理论的研究进展和存在的问题。     

Coronal Fe xiv Emission During the Whole Heliosphere Interval Campaign

Solar Cycle 24 is having a historically long and weak start. Observations of the Fe xiv corona from the Sacramento Peak site of the National Solar Observatory show an abnormal pattern of emission compared to observations of Cycles 21, 22, and 23 from the same instrument. The previous three cycles have shown a strong, rapid ??Rush to the Poles?? (previously observed in polar crown prominences and earlier coronal observations) in the parameter N(t,l,dt) (average number of Fe xiv emission features per day over dt days at time t and latitude l). Cycle 24 displays a weak, intermittent, and slow ??Rush?? that is apparent only in the northern hemisphere. If the northern Rush persists at its current rate, evidence from the Rushes in previous cycles indicates that solar maximum will occur in early 2013 or late 2012, at least in the northern hemisphere. At lower latitudes, solar maximum previously occurred when the time maximum of N(t,l,365) reached approximately 20° latitude. Currently, this parameter is at or below 30° and decreasing in latitude. Unfortunately, it is difficult at this time to calculate the rate of decrease in N(t,l,365). However, the southern hemisphere could reach 20° in 2011. Nonetheless, considering the levels of activity so far, there is a possibility that the maximum could be indiscernible.     

银河系铝元素丰度研究

恒星的Al元素丰度可以为探索星团和星系的化学演化提供重要线索.通过系统分析银河系薄盘、厚盘、核球、银晕以及M4、M5等球状星团中恒星的[Al/Fe]随恒星金属丰度[Fe/H]的变化趋势,得出银河系薄盘、厚盘和核球恒星的[Al/Fe]随着[Fe/H]的增加而缓慢下降,而球状星团M4和M5恒星的[Al/Fe]随[Fe/H]增加没有下降趋势,这暗示Ia超新星对M4和M5恒星元素丰度的贡献比较小.详细研究了银河系恒星[Al/Fe]与[Mg/Fe]、[Na/Fe]的相关性,结果表明银河系场星的[Al/Fe]与[Mg/Fe]正相关,但在球状星团M4和M5恒星中未见此相关性;银河系盘星及M4和M5等球状星团恒星的[Al/Fe]与[Na/Fe]都存在正相关.     

The Global Context of Solar Activity During the Whole Heliosphere Interval Campaign

The Whole Heliosphere Interval (WHI) was an international observing and modeling effort to characterize the 3-D interconnected ??heliophysical?? system during this solar minimum, centered on Carrington Rotation 2068, March 20??C?April 16, 2008. During the latter half of the WHI period, the Sun presented a sunspot-free, deep solar minimum type face. But during the first half of CR 2068 three solar active regions flanked by two opposite-polarity, low-latitude coronal holes were present. These departures from the quiet Sun led to both eruptive activity and solar wind structure. Most of the eruptive activity, i.e., flares, filament eruptions and coronal mass ejections (CMEs), occurred during this first, active half of the interval. We determined the source locations of the CMEs and the type of associated region, such as active region, or quiet sun or active region prominence. To analyze the evolution of the events in the context of the global solar magnetic field and its evolution during the three rotations centered on CR 2068, we plotted the CME source locations onto synoptic maps of the photospheric magnetic field, of the magnetic and chromospheric structure, of the white light corona, and of helioseismological subsurface flows. Most of the CME sources were associated with the three dominant active regions on CR 2068, particularly AR 10989. Most of the other sources on all three CRs appear to have been associated with either isolated filaments or filaments in the north polar crown filament channel. Although calculations of the flux balance and helicity of the surface magnetic features did not clearly identify a dominance of one region over the others, helioseismological subsurface flows beneath these active regions did reveal a pronounced difference among them. These preliminary results suggest that the ??twistedness?? (i.e., vorticity and helicity) of subsurface flows and its temporal variation might be related to the CME productivity of active regions, similar to the relationship between flares and subsurface flows.     

Space Observation and Study of the Sun.

The ejection of energetic electrons and protons,and γ-ray burst are revealed by solar space observations,which have confirmed some related theories of solar radio emission and uncovered the nuclear reaction in flares.The difference and relationship between CME and plasma cloud in flares are shown by space observations.The hot and cold regions of flares are known.The theory of nonlinear magnetohydrodynamics is developed by solar and heliospheric magnetic field observations.     

Global Variations and Asymmetry of the Sun During Extremely High Activity in October–November 2003

The data of the Coronas F satellite and other spacecraft were used to show that, in October–November 2003, global variations in brightness occurred in all spectral regions of the solar electromagnetic radiation. The variations were asymmetric in heliolongitude. This phenomenon was accompanied by an extremely strong energy release in the form of coronal-mass ejections and solar flares. The most powerful of them took place on the solar side that was characterized by an enhanced brightness even before these events. As a result, superimposed corotating and sporadic disturbances, which are partly correlated, can be traced in parameters of the solar atmospheric radiation, flows of the solar-wind plasma, and heliospheric magnetic field.__________Translated from Astronomicheskii Vestnik, Vol. 39, No. 3, 2005, pp. 195–201.Original Russian Text Copyright © 2005 by Veselovsky, Dmitriev, Zhitnik, Zhukov, Zel’dovich, Kuzin, Naumkin, Persiantsev, Ryazanov, Shugai, Yakovchuk, Bogachev, Shestov.     

A paradox in measuring the magnetic field of the Sun

Significant discrepancies are often observed among the values of the mean magnetic field (MMF) of the Sun as a star observed by various instruments using various spectral lines. This is conventionally attributed to the measurement errors and “saturation” of a solar magnetograph in fine-structure photospheric elements with a strong magnetic field. Measurements of the longitudinal MMF performed in 1968–2006 at six observatories are compared in this paper. It is shown that the degree of discrepancy (slopes b of linear regression lines) varies significantly over the phase of the 11-year cycle. This gives rise to a paradox: the magnetograph calibration is affected by the state of the Sun itself. The proposed explanation is based on quantum properties of light, namely, nonlocality and “coupling” of photons whose polarization at the telescope-spectrograph output is determined by spacious parts of the solar disk. In this case, the degree of coupling, or “identity,” of photons depends on the field distribution in the photosphere and the instrument design (as Bohr said, “the instrument inevitably affects the result”). The “puzzling” values of slope b are readily explained by the dependence of the coupling on the solar-cycle phase. The very statistical nature of light makes discrepancies unavoidable and requires the simple averaging of data to obtain the best approximation of the actual MMF. A 39-year time series of the MMF absolute value is presented, which is indicative of significant variations in the magnitude of the solar magnetic field with a cycle period of 10.5(7) yr.     

The Horizontal Component of Photospheric Plasma Flows During the Emergence of Active Regions on the Sun

The dynamics of horizontal plasma flows during the first hours of the emergence of active region magnetic flux in the solar photosphere have been analyzed using SOHO/MDI data. Four active regions emerging near the solar limb have been considered. It has been found that extended regions of Doppler velocities with different signs are formed in the first hours of the magnetic flux emergence in the horizontal velocity field. The flows observed are directly connected with the emerging magnetic flux; they form at the beginning of the emergence of active regions and are present for a few hours. The Doppler velocities of flows observed increase gradually and reach their peak values 4?–?12 hours after the start of the magnetic flux emergence. The peak values of the mean (inside the ±?500 m?s^?1 isolines) and maximum Doppler velocities are 800?–?970 m?s^?1 and 1410?–?1700 m?s^?1, respectively. The Doppler velocities observed substantially exceed the separation velocities of the photospheric magnetic flux outer boundaries. The asymmetry was detected between velocity structures of leading and following polarities. Doppler velocity structures located in a region of leading magnetic polarity are more powerful and exist longer than those in regions of following polarity. The Doppler velocity asymmetry between the velocity structures of opposite sign reaches its peak values soon after the emergence begins and then gradually drops within 7?–?12 hours. The peak values of asymmetry for the mean and maximal Doppler velocities reach 240?–?460 m?s^?1 and 710?–?940 m?s^?1, respectively. An interpretation of the observable flow of photospheric plasma is given.     

Temperature of Polar Corona of the Sun According to Kislovodsk Observations During 1957–2002

We continued a study of the long-term variations of temperature in the solar corona at all latitudes (Makarov, Tlatov, and Callebaut, 2002a). The series of the green (Fe xiv 530.3 nm; KI₅₃₀₃) and red (Fe x 637.4 nm; KI₆₃₇₄) coronal intensities for 1957–2002 has been obtained using the coronal observations at the Kislovodsk Solar Station. The mean monthly coronal intensities have been calculated at all latitudes (0–90^˚) and in the high latitude (45–90^˚) zones. It was found that the value of KI₆₃₇₄/KI₅₃₀₃increased about 2.0 times at the high latitudes during the last 45 years. This corresponds to a decrease of the average temperature by 0.1 ×10⁶K of the polar corona. We suppose that a polar decrease of coronal temperature is connected with an increase of the area of polar zones A _PZoccupied by unipolar magnetic fields (Makarov et al., 2002) and, probably, with an increase of the area of polar coronal holes. The maximum ratio KI₆₃₇₄/KI₅₃₀₃is observed during the minimum sunspot activity.     

钡星重元素丰度的再研究

在包括双星及逃逸物质的系统总角动量守恒模型的基础上,采用星风质量吸积机制,由伴星通过逐次脉冲从主星吸积物质并与其外包层进行混合的模型出发,自洽地计算了钡星的重元素超丰,并给出理论计算结果与观测值的比较．计算结果表明,当取Ｂｏｎｄｉ－Ｈｏｙｌｅ质量吸积率的五分之一作为实际吸积率时,对于轨道周期较长（Ｐ＞１６００天）、相距较远的钡星系统,在误差范围内,理论计算曲线与大多数样品星的重元素丰度观测值相符合;而对于ＨＤ２０４０７５和ＨＤ１６４５８两颗钡星,将质量吸积率增大为Ｂｏｎｄｉ－Ｈｏｙｌｅ质量吸积率的二分之一时,计算结果与观测值符合较好,这表明质量吸积率在Ｂｏｎｄｉ－Ｈｏｙｌｅ质量吸积率的十分之一至二分之一之间．对于具有较短轨道周期（Ｐ＜６００天）的钡星系统,计算结果与丰度观测值偏差较大,表明钡星系统中还有其它的形成机制．     

Acoustic Mode Frequencies of the Sun During the Minimum Phase Between Solar Cycles 23 and 24

We investigate the spatial and temporal variations of the high-degree mode frequencies calculated over localized regions of the Sun during the extended minimum phase between solar cycles 23 and 24. The frequency shifts measured relative to the spatial average over the solar disk indicate that the correlation between the frequency shift and magnetic field strength during the low-activity phase is weak. The disk-averaged frequency shifts computed relative to a minimal activity period also reveal a moderate correlation with different activity indices, with a maximum linear correlation of about 72?%. From the investigation of the frequency shifts at different latitudinal bands, we do not find a consensus period for the onset of solar cycle 24. The frequency shifts corresponding to most of the latitudes in the northern hemisphere and 30° south of the equator indicate the minimum epoch to be February 2008, which is earlier than inferred from solar activity indices.     

A mechanism of helicity variations on the Sun

Helicity of solar magnetic fields plays an important role in dynamo theories of the solar cycle. The helicity has been known to vary with the main 11-year period (Hale's cycle). Recent observations have revealed significant helicity variations on a shorter time scale, with a characteristic period of approximately 2 years. We suggest an explanation for the observed variations of the magnetic helicity, based on our model of the double magnetic cycle of solar activity. The quasi-biennial variations of the helicity are the consequence of the influence of erupted magnetic fields of the main cycle on the helicity in the regions of generation of the high-frequency component of magnetic field. This model suggests that the low-frequency component is generated at the base of the convective zone due to large-scale radial shear /r of angular velocity . The high-frequency component may be generated in the subsurface region due to latitudinal shear / or due to the radial shear in this region.