分子外向流源的近红外观测及红外谱分析  

NEAR INFRARED OBSERVATIONS AND ANALYSES OF MOLECULAR OUTFLOWS

作　　者：孙锦[1] 吴月芳[1] 毛信杰[2] 李守中[2] 

机构地区：[1]北京师范大学天文系 [2]北京大学地球物理系

出　　处：《天文学报》1991年第2期134-144,共11页Acta Astronomica Sinica

基　　金：国家自然科学基金

摘　　要：本文给出了21个分子外向流源和两个具有稠密核的非分子外向流源的近红外观测结果.同时结合它们的IRAS和其它地面台站的红外观测资料,分析了分子外向流源红外谱的某些特性,平均地看,在2.28μ和25μ间分子外向流源的谱斜率要大于非外向流源的谱斜率.大多数双极外向流的谱斜率则大于2.采用修正的黑体光球模型计算了分子外向流源中心年青天体和拱星包层对JHK观测流量的贡献.对那些已知热光度的源,通过模型拟合导出了其中心星的光球温度和拱星消光.结果表明:与分子外向流成协的年青星,大多数可能是 TTauri星(5000—7000K)或发射线—星(9000—26000K).由JHK流量导得的拱星消光大约在10—20星等.所有这些事实,陡的红外能谱,强的拱星消光和高的红外光度比率都说明分子外向流源仍然是深嵌在分子云稠密核内部或附近的年青天体.本文采用普朗克函数和λ>35μ时的λ^(-1)尘埃发射率模型对(3.5—25μ)和(60—160μ)的红外谱进行了模型拟合,由5个源的计算结果得到的分子外向流源拱星包层的温度分布规律为Td(r)ocr^-(0.39-0.48),与和HII区成协分子云的理论结果相近.J, H, K photometric observations of 21 molecular outflow sources and two non-outflows near the dense cores of molecular clouds are made with the 1.26M infrared telescope at Xing-long station. The outflow sources are: LKH_α 198, W3—IRS5, AFGL 437, AFGL 490, LKH_α 101, HL Tau, HH 24, Mon R2, GGD 12—15, S255—IRSI, AFGL 961, NGC 2264, S87, S88 B, S—106, AFGL 2591, V1331 Cyg, V645 Cyg, S140, NGC 7538, MWC 1080. The non-ou^+-flows are CW Tau and DO Tau. Combined with the IRAS data and other ground-based in-frared data, some properties of the infrared spectra of molecular outflows are presented. For comparison we calculate the spectral slopes S of all observed sources between 2.28 to 25μm (S=d logF_v/d logλ). We find that, on the average, the slopes of outflows are larger than those of non-outflows and the slopes are larger than 2.0 for most of bipolar outflows. The infrared luminosities from 1 am to 100 μm are also obtained. Using the modified blackbody photospheric model, we calculate the contributions of the central young stars and circumstellar dust envelopes to the observed J, H, K fluxes. If he bolometric luminosities of outflows are given, combining interstellar reddening curve and observed J, H, K fluxes, the photopheric temperatures of central young stars and circumstellar extinction Av(IR) are also derived by best model fitting. The results show that most of the central young objects associated with molecular outflows are T Tauri-like stars (5000—7000 K) or emission-line stars (9000—26000K). The circumstellar extinctions Av(IR) derived from near infrared photometrics are 10—20 mag. All these facts, the steep—spectrum, strong circumstellar extinction and high infrared luminosity ratio confirm that the molecular outflows are heavily obscured objects and still lie in or close to the dense cores in molecular clouds. In this paper, the model fitting for mid-infrared (3.5—25 μm) and far-infrared (60—160 μm) emissions are obteined by performing a least-square fit to three or four photometri

关 键 词：红外测光 分子外向流 主序前星 

分 类 号：P112[天文地球—天文学]