Mode Identification from Line Profiles using the Direct Fitting Technique

The method of moments and the direct fitting method are the onlyspectroscopic methods of mode identification which allow a determination ofall pulsational parameters. The pulsation parameters are required to predictthe light amplitude and phase which can be important discriminants in modeidentification. The direct fitting method has several advantages over themethod of moments. It is not restricted to low spherical harmonic degree or form of the eigenfunction and is not sensitive to the placement of the continuum. In the last few years the method has been applied to several different types of stars. We briefly describe the method and give someexamples of its application.     

Emission Line Profiles of Warped Disks in the Kerr Spacetime

The calculations of emission line pro?les of a warped disk in the Kerr spacetime have been discussed in this paper. The main content consists of two parts. In the ?rst part, the geodesic motion in the Kerr spacetime and the equations of motion in integral form, as well as the method to obtain the solution with the Weierstrass’ elliptic functions are presented. Using the Weierstrass’ elliptic functions, the Boyer-Lindquist (B-L) coordinates and the affine parameter o are semi-analytically expressed as the functions of a parameter p. Then a code named ynogk (Yunnan Observatory Geodesic Kerr) is introduced based on the above discussions to calculate very fast the null geodesic in the Kerr spacetime. As an application of ynogk, the emission line pro?les of warped disks are investigated in detail in the second part of this paper. Here the structure model of warped disks is based on the results of Bardeen and Petterson in 1975, and the line pro?les are computed with the ray tracing method. Finally, the discussions and conclusions of the calculated results are presented. It is indicated that the line pro?les are dependent mainly on the inclination and azimuthal angles of the observer, as well as the index of emissivity, and that they may have a triple-peaked even multi-peaked structure, different from the double-peaked structure in the line pro?les of a standard thin accretion disk.     

用惩罚函数法拟合耀斑后环光谱

在光谱拟合分析过程中,由于谱线的不对称,目标函数呈现出较强的非线性;拟合参数增多,需要对拟合参数的定义域进行约束。本文利用完全线性化方法处理非线性目标函数,用惩罚函数法对拟合参数约束。并用这种方法,拟合计算了1984年2月18日环珥的一些不对称谱线。     

黑洞发光环谱线轮廓的精确解

围绕黑洞作开普勒运动的环状发光物所发射的光，将受到多普勒颇移和引力的综合作用．本文用光子输运方程方法，针对洛仑兹型发射谱线，求出在Schwarzschild度规下谱线轮廓的精确解，并讨论了Hercules星系团中类星体1604＋179光谱的认证．     

Synthesis of Line Profiles and Radial Velocity Curves for X-Ray Binary Systems

Line profiles and radial velocity curves for optical stars in X-ray binaries are calculated taking into account ellipticity of the optical star and X-ray heating effect.     

The Effect of Mass Motions Inside the Coronal Loops on Emission Line Profiles

The observed green coronal emission line profiles have been often found to have multi-components. Further examinations reveal that the occurrence of multi-components in line profiles is related to the solar cycle variations as well as the activity of the coronal region. The spatial correspondence between the intense loops in active regions and strong multi-components in line profiles suggests that the presence of loops affects the line shapes. The emission line profiles have been found to be fitted well with single or multi-Gaussians with line-of-sight velocities up to 70 km s–1. A simple radiative transfer model of coronal emission line profiles is developed which shows that coronal loops with mass motions inside may give rise to multi-components in line profiles. The effects of loop parameters such as electron density, flow velocity and kinetic temperature and the line-of-sight variations are studied. It is found that line profiles strongly reflect the physical conditions inside the loop.     

几何薄光学厚吸积盘谱线轮廓及成像研究

假设位于黑洞赤道面上做圆形轨道运动的吸积盘是几何薄、光学厚的.利用光子追踪法计算在Kerr度规下的光子运动轨迹,通过数值计算研究薄吸积盘的相对论谱线轮廓及成像.在大角度观测时,吸积盘下表面的光子对谱线轮廓及成像的影响是显著的.     

Emission Line Profiles and Images of Geometrically Thin and Optically Thick Accretion Disks

Under the assumption that the accretion disk around a Kerr (spinning) black hole is geometrically thin and optically thick, the trajectories of photons in Kerr metric are calculated by using the photon tracing method. And by numerical calculations, we have made a study on the relativistic iron line profiles and images of thin accretion disks. The result shows that viewing at large inclination angles, because of the contribution of the photons from the lower surface of the accretion disk, the line profile becomes double-peaked and the flux image is also significantly modified.     

On the Shape of H and K Ca II Line Profiles in Sunspot Umbral Spectra

Emission cores of the H and K Caii lines observed in sunspot umbral spectra are mainly single-peaked, while semi-empirical umbral models predict their double-peak character. It is verified whether a single-peaked profile can be the result of the smearing of an originally double-peaked profile by macroturbulence. The integral convolution equation is solved for measured H and K profiles, and it is shown that, also after the deconvolution, they remain single-peaked even at an r.m.s. value of the macroturbulence velocity equal to 5 km s-1.     

Towards an Understanding of Radial Velocity Shift in Uv Spectra of Symbiotic Stars

A systematic redshift of high ionization resonance emission lines relative to the intercombination lines was found by Friedjung et al. (1883, A & A 126, 4071983) in the UV spectra of a number of symbiotic binaries. The interpretation was not then clear. We present a study of archival IUE and GHRS/HST spectra of the symbiotic binary CI Cyg. The shift varies during the orbital cycle which can be understood in terms of the presence of strong circum-binary line absorption formed in an outer expanding region.     

Solar Plasma Density and Spectrum of Accelerated Particles Derived From the 2.223-Mev Line of a Solar Flare

The time profile of the neutron capture line of 2.223 MeV for the flare of 16 December 1988 (its third peak) is analyzed. The enhancements of plasma density in the deep photospheric layers of the Sun under the flare region (an effect of density enhancement) have been deduced by the SINP calculation code. These enhancements are studied based on several modified models of the lower chromosphere, photosphere, and convection zone. Additionally, the case has been examined when the neutron source is placed at the top of the photosphere. The energy spectrum of accelerated particles (protons) is shown to evolve with time. Assuming a stochastic mechanism of acceleration and a Bessel function for the spectrum, we find the spectral index α T to increase from 0.005 to 0.1 during the decay phase of the burst; i.e., the proton spectrum becomes harder. Density enhancements found in the flare of 16 December 1988 are consistent with our previous results on the density enhancement effects deduced for two other flares, 6 November 1997 and 22 March 1991. It is suggested that density enhancements in the deep layers of the photosphere may be rather common features of powerful solar flares. B.M. Kuzhevskij is deseased.     

高压输电线对射电望远镜的电磁干扰

一方面,根据国际电信联盟(International Telecommunication Union,ITU)关于射电天文的保护标准,结合高压输电线电磁干扰的特性,分析了射电望远镜对高压输电线电磁干扰的限度;另一方面从物理机制出发建立高压输电线电晕放电辐射的电振子模型,运用电振子的镜像法,研究了其辐射功率随距离的衰减规律.同时还考虑500 m口径球面射电望远镜(Five hundred meters Aperture Spherical Telescope,FAST)的具体情况,分析了在FAST周围架设高压输电线应离开望远镜之间最小距离和应注意的问题.     

Emission from an Inhomogeneous Plasma: Line Intensities and Determination of Elemental Abundances in Gaseous Nebulae with Fluctuations of Te and ne

A method is proposed for determining the abundances of chemical elements in planetary nebulae based on allowance for the actual distribution functions of errors in measuring line intensities. Fluctuations both in temperature and in mass density of a nebula are taken into account in the proposed method. The results of a determination of C and O abundances and of the amplitudes of temperature and density fluctuations are given.     

Studies of Plasma Dynamics in a Small Plasma Focus Operating in Hydrogen-Argon Mixtures

We report on experimental observations in PFP-I, a small 3.8 kJ plasma focus, which is operated in Hydrogen-Argon mixtures to investigate the effect of parameter modifications on the overall performance of the device. An extensive array of diagnostics is been used, which includes voltage and current probes in the external circuit, a novel small magnetic probes array located along the cathode rods, filtered PIN diodes located side and end on, and filtered multi-pinhole and slit-wire X-ray camera. Extended operating range from below 0.2 Torr upwards has been achieved. Hot spot formation has been investigated as a function of H₂-Ar mixing ratio. Hot spot sizes around 150 m in the soft X-ray region, have been inferred from the slit-wire measurements. Pin-hole time integrated X-ray pictures and time resolved PIN diode measurements have been used to determine characteristic hot-spot temperatures in the 350 to 450 eV range.     

Main Cause of the Poloidal Plasma Motion Inside a Magnetic Cloud Inferred from Multiple-Spacecraft Observations

Although the dynamical evolution of magnetic clouds (MCs) has been one of the foci of interplanetary physics for decades, only few studies focus on the internal properties of large-scale MCs. Recent work by Wang et al. (J. Geophys. Res. 120, 1543, 2015) suggested the existence of the poloidal plasma motion in MCs. However, the main cause of this motion is not clear. In order to find it, we identify and reconstruct the MC observed by the Solar Terrestrial Relations Observatory (STEREO)-A, Wind, and STEREO-B spacecraft during 19?–?20 November 2007 with the aid of the velocity-modified cylindrical force-free flux-rope model. We analyze the plasma velocity in the plane perpendicular to the MC axis. It is found that there was evident poloidal motion at Wind and STEREO-B, but this was not clear at STEREO-A, which suggests a local cause rather than a global cause for the poloidal plasma motion inside the MC. The rotational directions of the solar wind and MC plasma at the two sides of the MC boundary are found to be consistent, and the values of the rotational speeds of the solar wind and MC plasma at the three spacecraft show a rough correlation. All of these results illustrate that the interaction with ambient solar wind through viscosity might be one of the local causes of the poloidal motion. Additionally, we propose another possible local cause: the existence of a pressure gradient in the MC. The significant difference in the total pressure at the three spacecraft suggests that this speculation is perhaps correct.