Further constraints on variation of the fine-structure constant from alkali-doublet QSO absorption lines

Comparison of quasar (QSO) absorption-line spectra with laboratory spectra provides a precise probe for variability of the fine-structure constant, α , over cosmological time-scales. We constrain variation in α in 21 Keck/HIRES Si  iv absorption systems using the alkali-doublet (AD) method in which changes in α are related to changes in the doublet spacing. The precision obtained with the AD method has been increased by a factor of 3:     . We also analyse potential systematic errors in this result. Finally, we compare the AD method with the many-multiplet method, which has achieved an order of magnitude greater precision, and we discuss the future of the AD method.     

Chemical evolution of the high redshift galaxies

We have tried to determine the rate of chemical evolution of high redshift galaxies from the observed redshift distribution of the heavy element absorption systems in the spectra of QSOs, taking into account the evolution in the intensity of the metagalactic UV ionizing radiation background, the radius and/or the co-moving number density of, and the fraction of mass in the form of gas in, the absorbers. The data for both the Lyman limit systems and the C IV systems have been fitted simultaneously. It seems that the abundance of carbon has possibly increased by about a factor of 5 to 20 from the cosmic time corresponding to the redshift ≃ 4 to 2. The data also suggest that either the radius or the co-moving number density of the galaxies increased with redshift up to z = 2.0 and decreased slowly thereafter. The total mass of the halo gas was higher in the past, almost equal to the entire mass of the galaxy at z = 4. The hydrogen column density distribution for Lyman limit systems predicted by the model is in agreement with the observed distribution.     

Red companions to a z=2.15 radio-loud quasar

We have conducted observations of the environment around the z =2.15 radio-loud quasar 1550–269 in search of distant galaxies associated either with it or the z =2.09 C  iv absorber along its line of sight. Such objects will be distinguished by their red colours, R − K >4.5. We find five such objects in a 1.5 arcmin² field around the quasar, with typical K ' magnitudes of ∼20.4 and no detected R -band emission. We also find a sixth object with K =19.6±0.3, and undetected at R , just two arcsec from the quasar. The nature of all these objects is currently unclear, and will remain so until we have determined their redshifts. We suggest that it is likely that they are associated with either the quasar or the C  iv absorber, in which case their properties might be similar to those of the z =2.38 red Ly α emitting galaxies discovered by Francis et al. The small separation between the quasar and the brightest of our objects suggests that it may be the galaxy responsible for the C  iv metal line absorption system. The closeness to the quasar and the red colour might have precluded similar objects from being uncovered in previous searches for emission from C  iv and damped absorbers.     

星载铷原子频率标准的可靠性研究

星载原子频率标准在许多空间系统中担当着重要的角色,其性能和可靠性对这些系统的功能有重要的影响。介绍了广泛使用的星载铷原子频率标准的基本工作原理,分析了影响其可靠性的各种因素,并探讨了提高其可靠性的基本途径。     

类氖铁(Fe XVII)离子能级及振子强度计算

利用原子数据模拟程序RCN／RCG、AUTOSTRUCTURE(AS)、GRASP分别对类氖铁的离子结构进行计算，计算过程包含了对波函数的相对论修正，计算结果包括电偶级光谱跃迁的能级间隔，谐振子强度，跃迁几率，并与实验值进行了比较，分析了3种原子数据模拟程序在计算原子结构上的精确度．     

Spectral and Photoelectric Studies of the Herbig Ae/Be Star HD 259431

Spectral and photoelectric (ubvy, H, H) observations of the Herbig Ae/Be star HD 259431 are reported. It is found that as its brightness fades, this star becomes bluer in the Paschen continuum and the intensity and equivalent width of the hydrogen emission lines increase. The spectral observations reveal significant variations in the intensity of the Mg II 4481 Å photospheric absorption line. A rise and fall in the luminosity by 0^m.04 within a period of 5-7 minutes was recorded. Radical variations in the H lineshape ("double" "P Cyg") and flare activity are not only observed in this star, but also in a number of HAEBE stars. It is suggested that flare activity may initiate a change in the velocity gradient at the base of the wind and, thereby, induce "double P Cyg" or "P Cyg single" transitions. The nonradial pulsations of this star are also discussed.     

新显色剂四-(3-磺基-4-氯苯基)卟啉分光光度法测定微量铜

研究了新显色剂四-(3-磺基-4-氯苯基)卟啉在微酸性介质中,表面活性剂OP与CPC存在下测定微量铜的显色反应。络合物在波长420 nm处有最大吸收峰,摩尔吸光度系数为3.44×105L·mol-1cm-1,用双峰双波长光度法测定摩尔吸光系数为6.72×105L·mol-1·cm-1,铜含量在0.5~4.5μg/25 m L范围内符合比耳定律。方法应用于矿样中微量铜的测定,结果令人满意。     

一种基于小波熵的时间尺度算法

结合小波分析和熵的基本理论,在分析国际原子时TAI的基础上,提出了基于小波熵的时间尺度算法．通过对原子钟信号进行多尺度分解,根据能量划分,综合所有尺度的小波系数得到小波熵,然后利用小波熵对原子钟进行加权．最后,通过某实验室的实测数据对算法进行了检验,结果表明:这种方法能够综合各原子钟信号在不同尺度上的频率波动特征,明显提高了时间尺度的稳定度．     

Physical parameters of the continuum emission layer of Mira type stars. II. Radii and expansion velocities

The Pulkovo Spectrophotometric Data Base is used to determine the expansion velocities and radii of the continuum emission layers of the stars RR SCO and OMICR CET. Dependences of the radii and velocities on the phase of the variability cycle are found which agree with the known values obtained from the layers which emit line radiation. __________ Translated from Astrofizika, Vol. 50, No. 4, pp. 557–564 (November 2007).