蓝致密矮星系谱的星族合成  

Population Synthesis for the Spectra of Blue Compact Dwarf Galaxies

作　　者：孔旭[1,2,3] 孔旭[1,2,3] 孔旭[1,2,3] 程福臻[1,2] 程福臻 周旭[2,3] 周旭[2,3] 陈建生[2,3] 陈建生[2,3] 

机构地区：[1]中国科学技术大学天体物理中心,合肥230026 [2]中国科学院国家天文观测中心,北京100012 [3]中国科学院-北京大学联合北京天体物理中心,北京100871

出　　处：《天体物理学报》1999年第4期380-392,共13页

基　　金：国家自然科学基金;国家攀登计划;中国科学院资助

摘　　要：利用星团谱样本的星族合成方法，分析了７个ＢＣＤＧ的光学谱，研究蓝致密矮星系（ＢＣＤＧ）内部的恒星形成历史、能源机制和尘埃分布情况．星族合成结果不仅能够解释ＢＣＤＧ的主要观测特征，解决ＢＣＤＧ研究中存在的一些问题，而且揭示了ＢＣＤＧ的一些未知的特性．谱合成结果表明：ＢＣＤＧ是年老的天体，其内部较早已经有恒星形成发生，恒星形成呈爆发式的，在ｔ＝５×１０７～１０９ｙｒ时的恒星形成率较高，最近（ｔ＝１０７ｙｒ）的恒星形成率开始下降；光谱分析显示大量大质量的年轻恒星提供了ＢＣＤＧ中心区的主要能源．利用扣除恒星吸收影响的发射线光谱，计算了发射线产生区的内红化值，发现它明显大于由连续谱计算得到的内红化值，这种差异的可能解释是ＢＣＤＧ内部尘埃对连续谱和发射线的产生区遮挡程度不同．最后，比较了ＢＣＧ和ＢＣＤＧ星族合成结果，提出了矮星系间一种可能的演化序列．In order to study the history of star formation, energy source and internal dust distribution in blue compact dwarf galaxies (BCDGs), we have compared the observed spectraof the nuclei of 7 BCDGs with the predictions of stellar population synthesis model. Theresults suggest that BCDGs are old galaxies, in which star formation occurs in short intense bursts separated by long quiescent phases. The star formation rate was very high during5 ×107 ~ 109 yr, but has now decreased. We find that the main energy source of BCDGscomes from young, massive stars. We have derived the inner reddening that affects thenuclear stellar population by the population synthesis method and the internal reddening ofthe emitting gas clouds from the Balmer line ratio and found the former to be consistentlyand significantly smaller than the latter; -this feature can be explained by a model of foreground dust clumps with different covering factors for the gas and stars. Finally, based onthe stellar population of BCGs (blue compact galaxies) and BCDGs, we suggest a detailedevolutionary link among different dwarf galaxies.

关 键 词：蓝致密矮星系 星族合成 内红化 恒星形成 星系谱 

分 类 号：P145.4[天文地球—天体物理]