新近发现的H_2O6_（16）－5_（23）脉泽速度时变的研究

A STUDY OF TIME VARIATION IN LSR VELOCITIES OF RECENTLY DISCOVERED H_2O6_(16)-5_(23)MASERS

本文作者用美国ＮＲＡＯ，ＧｒｅｅｎＢａｎｋ４３ｍ和中国科学院紫金山天文台德令哈１３．７ｍ射电望远镜，对新近发现的水６１６—５２３脉泽相隔约１年的三次观测结果作了本地静止标准速度时变的研究，在分析实测结果时采用了参量ＬＳＲ速度延展（Ｖｓｐｄ），相继两历元观测的谱征峰值速度极差（ＤＶ）和速度位移（ＤＶ）．结果表明可将分析样本归纳为两类：Ａ类，微弱多数样本的速度时变给出的谱征位移显示脉泽结的替代效应．这种情况是在观测波束内存在若干未分解的脉泽斑引起的，主要受制于共同激发源的简单运动；Ｂ类，余下的样本给出较大的速度极差，呈现脉泽结整体的运动，涉及激发源的加速和减速以及抽运机制．

We present the spectra of our recently discovered H,O (616- 523 ) masers associ-'ated with outflows at three epochs, and a study of the time variations in LSR velocities during that period. Time intervals between the epochs are approximately one year for all sources. The NRAO* 43m telescope, U .S .A. and the Delingha 13. 7m telescope of the P .M .O. **, China, were used. The analyzed parameters are the LSR velocity spead, the extreme differences DV, of the LSR velocity from. one epoch to another, and the LSR velocity offset dV. The results show that a slender majority of samples reveals a a 'substitutive' effect of the maser knots (Type A), which produces the LSR velocity offxet dV of the features. This situation is caused by the existence of several unresolved maser spots (a clustered area of maser knots) within the observing beam, in which dV is restricted by the simple motion of the common exciting source. The remaining samples exhibit the overal motion of the knot ensemble (Type B ), which produces the extreme differences of the LSR velocities, DV. The latter may involve the acceleration and deceleration of the exciting source, and the pumping mechanism.