摘要
本文从IRAS点源星表（PSC）中选择了一批流量只F100μ≥500Jy，且属于正在形成或早期演化阶段的强远红外源，利用北京天文台兴隆观测站的1.26m红外望远镜，对这批源进行了J、H、K波段的近红外观测，得到了12个源的第一次J、H、K测光资料．结合外台站的红外观测资料和IRAS点源星表数据，我们对强远红外源的红外发射进行了修正的黑体光球模型、双壳层尘埃发射模型以及详细的辐射转移等模型的拟合，得到了这些源的一系列重要的物理参量，如中心星的等效光球温度，近红外消光以及包层的尘埃温度和密度随半径变化的幂律等．本文利用红外导出的中心星光球温度和光度，得到了与这些强远红外源成协的大质量年轻天体在赫罗图上的位置和演化特征．我们发现，对质量一定的大质量年轻星，沿着向主序演化的方向，红外谱在12μ－60μ间的斜率S有逐渐增大的趋势；而对演化到同一时间线的星，随着质量的增大，S也有增大的趋势．本文分析了这一性质．并提出了利用红外资料研究赫罗图的方法，它是一种研究深埋于分子云和尘埃包层的大质量年轻星早期演化的有效方法．
Because of being embedded deeply in molecular clouds and dust envelopes, theyoung stellar objects (YSOs) in the formation and early evolution are almost invisible.In order to learn about the feature of this kind of objects, a set of bright far-infraredsources (F100μ≥500Jy) are selected from IRAS- PSC. Most of them are in the formationand early evolution stages. Their infrared luminosities are larger than 103L, so theyare associated with high- mass YSOs. Their J, H, K photometric obselvations weremade with the 1.26m infrared telescope at Xinglong Station of Bejing AstronomicalObservatory. Combined with these data, the infrared information of other stations andIRAS-PSC data, the modified blackbody photospheric model, double-shell dustemission model and detailed radiation transfer model were used to fit the observedinfrared t1uxes. Based on this model fltting, some physical parameters, such as thephotospheric temperature of the central star, the circumstellar extinction and thermalstructure of dust shell, were derived. Using the derived photospheric temperatures andcorresponding stellar luminosities, we have determined the positions on an extendedH-R diagram and the evolution properties of the investigated bright far-infrared sources.We have found that there is a trend of continuous increase of the infrared spectralslope S (12-60) from 12μ to 60μ, along the direction to main sequence stars at thesame mass line of H-R diagram. For the YSOs, which are evolving at the same time,there is also a trend of increase of S (12-60) with mass. In this work we analyzedthe nature of bright far-infrared sources. It seems that the extended H-R diagrampresented in the paper is a good means to study this kind of objects, which aredeeply embedded in molecular clouds and dust envelopes.
出处
《天文学报》
CSCD
北大核心
1997年第4期412-425,共14页
Acta Astronomica Sinica
基金
国家自然科学基金
中科院光学天文联合开放实验室资助
关键词
恒星
形成时期
远红外源
红外发射
赫罗图
star formation, near infrared photometry, infrared spectral distribution, H-R diagram
