NGC7538的近红外偏振成像(英文)

NEAR INFRARED POLARIMETRIC IMAGING OF NGC7538

介绍恒星形成区ＮＧＣ７５３８的Ｈ和Ｋｓ波段偏振成像的观测结果．近５′视场的偏振图像揭示了与亮红外源ＩＲＳ１１１成协的年轻星团和红外星云的复杂结构．ＩＲＳ１３星云的偏振图像表明星云的近红外辐射主要来自对深埋红外源ＩＲＳ１的反射；其形态可解释为颜色很红的高偏振的壳层包围着的低消光气泡．ＩＲＳ１周围的近红外的偏振强度在ＩＲＳ１双极分子外流方向上呈现出一较小的壳结构．ＩＲＳ４在近红外表现为双源，其中较红的源ＩＳＲ４ｂ周围观测到中心对称的偏振图像．ＩＲＳ５与亮星云成协，ＩＲＳ６则处于一组星的中心．在ＩＲＳ５和ＩＲＳ６周围的星云中没有观测到偏振．ＩＫＳ９照亮着两块星云，ＩＲＮ１和ＩＲＮ２．ＩＲＮ１星云有很好的锥形并包含一高偏振的喷流成分．云中较高偏振的部分对应较蓝的颜色，显示着其较大的视向张角的外流腔结构．与复杂的ＩＲＳ９区分子外流相比较，ＩＲＮ１星云与在ＮＥＳＷ方向的外流相符合．首次证认了ＩＲＳ１１近红外点源。

We present H and K s polarimetric images in a ～5′ field of star forming region NGC7538. The polarimetric images reveal the complex structure of infrared nebulosities and clusters of young stars, associated with the bright infrared sources IRS 1 11. The polarization pattern in the IRS 1 3 nebula shows a dominant illumination from deeply embedded source IRS 1. The morphology of the nebula can be modeled by a low extincted bubble enclosed by redder and highly polarized shell. Polarized near infrared intensity in IRS 1 region exhibits a smaller shell structure, consistent with the direction of molecular outflow centered on IRS 1. The IRS 4 is resolved into a double source, and a centro symmetric polarization pattern is observed around the eastern redder source, IRS 4b. IRS 5 is associated with bright nebulosity and IRS 6 is surrounded by a group of stars. No polarization is detected in the extended nebulosity around IRS 5 and IRS 6. The nebulosity in the IRS 9 region consists of two nebular components illuminated by IRS 9, IRN 1 and IRN 2. The IRN 1 nebula shows a conical shape and a highly polarized jet; the large polarization coincident with blue colors in the nebular indicates an outflow cavity, with a wide light of sight opening angle. Compared with the complex modecular outflows in the IRS 9 region, IRN 1 nebula is consistent with a NE SW outflow. We identify a near infrared source as IRS 11, surrounded by a group of point sources and very faint nebulosity.