银河系和河外星系的消光规律及尘埃性质

The Extinction Laws and Dust Properties of the Milky Way and External Galaxies

对星际消光的研究,有利于人们还原天体本来的光度与颜色,也有利于人们了解星际尘埃的性质。小麦哲伦云紫外波段的消光曲线比银河系紫外波段的消光曲线更加陡峭,大麦哲伦云的平均消光曲线介于银河系的平均消光曲线与小麦哲伦云的消光曲线之间。M31的消光曲线与银河系的消光曲线类似,都存在2 175?A的驼峰和紫外波段增强的特征。此外,对高红移河外星系尘埃的星光衰减曲线以及M33,M101,NGC 2207,M82,Ia型超新星、星暴星系、类星体和活动星系核消光规律的研究结果表明,它们所处的星际环境不同,消光规律及尘埃特征也不同。

Dust extinction is crucial to recover the intrinsic energy distributions of celestial objects and infer the characteristics of the interstellar dust.An overview of our current understanding of the interstellar extinction laws of the MilkyWay(MW)and external galaxies is presented.In the MW,the extinction law in the ultraviolet(UV)and optical can be characterized by a one-parameter function of RV≡AV=E(B﹣V);the near-infrared(IR)extinction law appears to be an approximately uniform power law of Aλ≈λ^﹣α;an“universal”flat extinction law is found in the mid-IR(3~8μm).In the Small Magellanic Cloud(SMC),the extinction curve rises steeply in the UV and lacks the 2 175A bump in the bar region.However,in the SMC wing region,the extinction curve rises less steeply in the UV and the 2 175A bump is present.In the Large Magellanic Cloud(LMC),the average extinction is intermediate between that of the MW and SMC.The 2 175?A bump in the star-forming regions of LMC 30 Dor and supershell LMC 2 is much weaker than that of the MW.For M31,the extinction curve resembles that of the MW.The attenuation laws of high redshift galaxies and the extinction laws of M33,M101,NGC 2207,M82,type Ia supernovae,starburst galaxies,quasars,and active galactic nucleus are also disscussed.