暗星云L134的稳定性及热特性

利用暗星云L134的光学观测及分子谱线观测的结果,估算了它的某些基本物理参数,讨论了该星云的稳定性及能量问题。 发现在L134的演化过程中,热压力及转动在制约其自引力坍缩中起一定作用,但不是重要因素,而磁场的支撑作用可能是比较重要的,L134不是在自由下落时间尺度t_(ff)上引力坍缩,而可能是在一个比较长的双极扩散时间尺度t_D上收缩。 本文还计算了L134的冷却率及加热率,表明引力克服热压力作功不是暗星云L134的有效加热源;宇宙线是L134的一个加热源,它能提供所需能量的～20％;磁场通过双极扩散释放能量可能为L134提供了一个重要的加热源。

The Stability and Thermal Properties of the Dark Cloud L 134

Using the results of optical observations and molecular line observations of the dark cloud L134, some basic physical parameters of the cloud are obtained and the stability and energy of the cloud are discussed.It is found that thermal pressure and rotation of the cloud are unimportant, while internal magnetic field may be more effective for supporting .the cloud against gravitational collapse. And the cloud could not collapse on the free-fall time scale but on a longer time scale of am-bipolar diffusion.The cooling and heating rates .in L134 are also calculated. The results show that the work done by the gravitation against thermal pressure is not an effective heating source, cosmic rays, however, may provide as much as about 20% heating energy required in L134. Calculation shows that internal magnetic energy released through the processes of ambipolar diffusion can supply the most part of energy required in LI 34, therefore it may be an excellent heat source.