银道面HII区复合体G18．2－0．3的射电及红外发射  

RADIO AND INFRARED EMISSION OF THE HII REGION COMPLEX:G18.2-0.3 IN THE GALACTIC PLANE

作　　者：孙锦[1] 吴月芳[1] 梁世光[1] 黄心泳 季德盛[1] 

机构地区：[1]北京师范大学天文系,北京大学地球物理系,中国科学院上海天文台

出　　处：《天文学报》1994年第4期353-361,共9页Acta Astronomica Sinica

基　　金：国家自然科学基金

摘　　要：本文作者用上海天文台的２５米天线和１２．２ＧＨｚ的接收系统，对银道面附近的一个ＨＩＩ区复合体Ｇ１８．２—０．３进行了射电连续谱观测．采用沿源运动轨迹，对观测曲线进行多子源模型拟合的方法，将该复合体中的６个子源从延展的ＨＩＩ区辐射中分离了出来，并导出了每个子源在１２．２ＧＨｚ频率上的流量和角大小．结合外台站在２６９５ＭＨｚ，４７５０ＭＨｚ和１０．５５ＧＨｚ上的流量还得到了这些子源的辐射频谱．分析表明它们具有热辐射性质．对具有射电复合线（Ｈ７６α）资料和角尺度的４个子源导出了它们的电子密度在（１—３）×１０２ｃｍ－３间．此外通过对Ｇ１８．２—０．３复合体子源ＩＲＡＳ资料的分析和模型拟合还得到了每个子源周围冷尘埃的等效黑体温度．其中４个子源并具有ＩＲＡＳ－ＬＲＳ资料．分析它们得到了与该ＨＩＩ区成协尘埃的性质．根据５个子源的ＩＲＡＳ流量、频带以及色改正因子又求出了这些子源在１—５００μｍ间的总红外光度在２×１０４—１０５Ｌ间．它表明与Ｇ１８．２—０．３中各子源成协的新形成星是一些大质量的ＯＢ型星，它们在同一个延展ＨＩＩ区中如此密集证明了大质量星“致密—堆积”形成模式的合理性．The continuum observations for the HII complex:G18.2 0.3 in the galactic plane at a new frequency 12.2GHz are made with the 25m radio telescope of Shanghai observatory. By adopting of the simultaneously model fitting for multisources along their motion orbits, six sub-sources are resolved out from extended HII region radiation. The flux density and angular size at 12.2GHz for each of sub-sources is also derived. Combining the observation data at 2695MHz, 4750MHz and 10.55GHz,it is found that the radiation spectra of the sources in G 18.2 0.3 are all characterized by its thermal radiation. For the 4 sub-sources which have radio recombination line(H76a) data and angular sizes, the electron densities are also derived.The average electron density is(1 3)× 102cm-3. Besides, the infrared nature of HII complex G18.2 0.3 is analysed.In the complex G18.2 0.3 five subsources are identified as IRAS point sources.By use of the model fitting for the IRAS fluxes of 5 subsources the effective black body temperature of surrounding cold dust are found out.4 IRAS sources out of 5 also have IRAS-LRS data. WIth these LRS spectra the properties of associated dust are discussed. The infrared luminosities (1 500μ) are calculated by using IRAS fluxes, frequency bandwidth and color correction. The calculated infrared luminosities (1 500μ) are 2 ×104 105L.It shows that the newly formed stars associated with these sub-sources are all high mass OB stars. They are concentrated so highly in an extended HII region that one can confirms that the 'closely-packed' star formation mode is reasonable for massive stars.

关 键 词：HII区 射电连续谱 红外发射 银道面 

分 类 号：P155.21[天文地球—天文学]