恒星形成时期强远红外源中的22GHz水脉发射与CO分子外向流关系的研究  

A STUDY OF THE RELATION BETWEEN 22 GHz H_2O MASERS AND CO OUTFLOWS IN INTENSE FAR-INFRARED SOURCES ON THE STAGES OF STAR FORMATION

作　　者：唐歌实[1] 孙锦 吕静[1] 

机构地区：[1]北京师范大学天文系,中国科学院紫金山天文台青海观测站,国防科工委北京飞控中心

出　　处：《天文学报》1996年第4期404-420,共17页Acta Astronomica Sinica

基　　金：国家自然科学基金

摘　　要：为揭示大质量星形成及早期演化中的一些重要特征，根据ＩＲＡＳ的流量，选择了一批Ｆ１００μ≥５００Ｊｙ的强远红外源，它们大多是处于恒星形成或早期演化阶段中的大质量的年轻天体，利用紫金山天文台青海观测站１３．７米射电望远镜，对它们分批进行了２２ＧＨｚ水脉泽的搜寻，得到了１１个新的水脉泽源．使用这些新的观测数据和ＩＲＡＳ资料，并结合外台站的水脉泽和ＣＯ分子外向流资料，对这类源进行了统计研究，结果表明：１．ＣＯ外向流的机械光度ＬｍＣＯ与远红外的积分光度ＬＦＩＲ相关，与１２─６０μ间的红外谱斜率Ｓ（＝Ｌｏｇ１０（Ｆ６０μ／Ｆ１２μ））反相关．２．Ｈ２Ｏ脉泽发射的积分光度ＬＨ２０与ＬＦＩＲ明显相关，与Ｓ无明显相关性．３．在ＬｍＣＯ一定时，相应的ＬＨ２Ｏ有一个下限，最强的外向流活动对应最强的Ｈ２Ｏ脉泽发射．４ＣＯ外向流及Ｈ２Ｏ脉泽的探测率均随远红外积分流量而增大．５．ＣＯ外向流的谱斜率趋于Ｓ偏小的区域，而Ｈ２Ｏ脉泽的谱斜率则分布在大的Ｓ范围，且较弥散．６．总样本中Ｈ２Ｏ脉泽的发生率大于ＣＯ外流的发生率；而在ＣＯ外向流中则Ｈ２Ｏ脉泽的探测率大于Ｈ２Ｏ脉泽中ＣＯ外向流的探测率．综合以上结果说明：大质量星和低质量星在形成过程中有?In order to reveal some important characteristics of massive stars in star formation and early stellar evolution, a group of bright far-infrared sources is selected from IRAS-PSC. Their IRAS fluxes at 100μm are larger than 500Jy. Most of them are massive young stellar objects during star formation and early evolution. Their infrared luminosities are larger than 103L. Using the 13.7m radio telescope at Qin hai Station of Purple Mountain Observatory, We carried out a search for the 22GHz H2O maser emission of selected sources (see Table 1). Eleven new H2O maser sources were found (see Table 2). By using the new H2O maser data, IRAS-PSC material as well as some other H2O masers and CO outflows information, we have made a statistical analysis and research. The main results are: 1. The mechanical lminosities of CO outflow CO outflows LmCO are correlated with the FIR luminosities LFIR, but anti-correlated with the infrared spectral indexes S[12-60] (log10 (F60μm /F12μm)). 2. The integrated luminosities of H2O masers LH2O are also correlated with the FIR luminosity LFIR, but are not correlated with S 3. There is a low limit for LH2O. as LmCO is fixed. The most intense outflow activty corresponds to the most intense H2O maser emission. 4.The detection rates of both H2O masers and CO outflows increase with integrated FIR fluxes. 5. The spectral indexes of CO outflows tend to smaller values, but those of H2O masers are spread to larger extent. 6. In the total samples, the occurrence rate of H2O masers is larger than that of CO outflows and the detection rate of H2O masers in CO outflows is larger than that of CO outflows in H2O masers. The statistical analysis mentioned above shows that massive star formation is different from low mass star formation. For instance, the variations of thickness of molecular and dust envelopes are different, and this gives rise to different characteristics of their infrared spectra. Besides, there are often different conditions for the pumping the H2O masers and the driving of CO outflows

关 键 词：恒星形成 强远红外源 水脉泽 分子外向流 

分 类 号：P152[天文地球—天文学] P155.22