猎户座IRc2的正、仲水脉泽的初步研究

A PRELIMINARY STUDY ON ORTHO AND PARA-WATER MASERS IN ORION IRc2

本文对猎户座ＩＲｃ２的正、仲水脉泽区的物理条件作初步研究。结果表明在动能温度６００Ｋ左右，尘埃温度低于３５０Ｋ，密度约１０^（８±０．５）ｃｍ^（－３）和水对氢分子相对丰度与速度梯度比为４×１０^（－９）ｐｃｓｋｍ^（－１）的条件下，仲水３_（１３）—２_（２０），５_（１５）—４_（２２）及正水６_（１６）—５_（２３），４_（１４）—３_（２１）脉泽可能同时呈现。这个区域的水丰度约为４×１０^（－６）。热尘埃并不使脉泽加强，碰撞抽运是激发星际水脉泽的一个可能机制。高密度下，准共振碰撞效应的计入可以解释６_（１６）—５_（２３）脉泽的高亮温度。

The physical conditions of interstellar para and ortho water maser regions are studied.Special attention is given to the correlations between para and ortho masers.Toward Orion IRc2 a water abundance of 4×10-6 is obtained,and it is found that under the physical conditions of Tk=600K,Td<350K,n(H2)=108±0.5scm-3 and F0/Vgr=3FP/Vgr=3×10-9 pc s km-1,the para 313-220,515-422 and ortho 616-523,414-321,maser actions appear simultaneously.The results also show that the hot dust would not strengthen the masers,collisional pumping is an available mechanism for the excitation of the interstellar water masers. Including the effect of quasi-resonance the brightness temperature of 61-523,maser could be higher than 1010K when the density is over 109 cm-3.