【摘要】 用1979—1980年食期间观测的11夜光谱底片,以做(Δλ)/(Δx)～λ色散曲线的方法,得出了ζAur的视向速度随位相的变化。其结果列于表2,绘于图1。 同以前食期间得到的视向速度相比较,结果基本一致,但在即将全食的大气食期间所得到的视向速度明显偏低。本文对这些结果做了初步讨论。更多还原

【Abstract】 In the ecliptic course of ξ, Aur from 1979 to 1980, we took its spectra by using a grating spectrograph on the quasi-Cassegrain focus of the 90 cm telescope located on Beijing Observatory, the dispersions are 17 A/mm and 29 A/mm. We selected 11 plates from these spectra to determine the radial velocities in its phases of total eclipse, atmospheric eclipse and outside the eclipse (see Table 1). The phases were measured by taking the time of middle of the eclipse J. D. 2444219.463 as zero.The coordinates of comparison spectra and the star spectra were measured by Abbe comparator. According to the wavelengths and the coordinates of the comparisonspectra and using the method of slide-mean, taking Kλi=(△λ/△ax)λi as the linear dis-persion of λi, we made a Kλi-λi diagram. In this diagram we may look up the linear dispersions of different wavelengths, then may find out the needed wavelengths from following formula: here, λFe,i and xFe,i represent the wavelengths and the coordinates of ith spectral line of the comparison spectra respectively; λs,j and xs,j-of jth spectral line of the star spectra; Ks,j and KFe,i represent the values of linear dispersion of the jth spectral line of the star spectra and the ith spectral line of the comparison spectra, which are looked up in dispersion diagram by taking the laboratory wavelengths of λs,j and λFe,i as lead-number. The following method of finding the sum is adopted to reduce the accidental error of measurement:with this λs,j the radial velocity will be calculable by general method.The average values of radial velocity of metallic lines, H. K. lines of CaII and Balmer lines on each plate are listed in Table 2. The variation of radial velocity versus different phases is drawn in figure 1. We may see from Table 2 and figure 1 that the value obtained by dispersion 17 A/mm is higher than that obtained by dispersion 29 A/mm, this difference is chiefly due to the flexure of the camera caused by its weight. The result of checking this spectrograph shows that the flexure of the camera with dispersion 17 A/mm is bigger than the another. If we calculate the correction of this flexure, the two results will be more coincident.The estimation of errors:1. The estimation of measuring errors: The sum of measuring values of different spectral lines on same plate measured along positive and negative directions should be a constant, the deviant from which is the measuring error, the measuring error is presented by mean square error, the averages of mean square errors of comparison spectral lines, metallic lines and hydrogen lines of the star are ±1.3 μ, ± 2.0μ and ±3.5 μ. respectively. To the dispersion 29 A/mm at λ= 4000 A, the errors of corresponding radial velocity is ±2.8 km/s, ±4.3 km/s and ±7.5 km/s respectively; To 17A/mm, they are ±1.7 km/s, ±2.5 km/s, and ±4.4 km/s.2. On assumption of the radial velocities of all spectral lines in multiplet of neutral iron being identical, we may use the mean square errors of radial velocity measured by all spectral lines of neutral iron to estimate the errors in the measurement, the drawing of dispersion diagram and the calculation. The average of mean square errors of these days is ±3.18 km/s, the maximum is ±4.67 km/s.Comparing with other values of radial velocities in its ecliptic course obtained formerly, these results coincide basically each other, but the radial velocity obtained by us just before the beginning of total eclipse is obviously lower than the others.更多还原