Distribution of the 3.3 micrometer Emission Band in the Galaxy

探测银河系平面上3.3微米辐射的低温红外相机的开发工作正在进行中。主镜和副镜(直径25厘米)的里奇-克雷蒂安光学系统已被证明具有良好的光学质量。将其安装在InSb 256X256阵列的低温恒温器中，获得了红外图像。对电子器件进行了调整，以便在相当强的背景辐射下实现最佳操作。该系统将于今年开始对银河系平面进行观测。对银河系中单个恒星形成区进行了红外成像和光谱测量，以研究恒星形成区辐射3.3微米辐射的演化阶段。在S140中，其红外源IRS1在3.1微米处有明显的冰吸收，偏振在吸收带上发生变化。然而，它没有3.3微米的发射，这可能意味着这个物体太年轻，不能发射3.3微米的辐射。我们还搜索了年轻恒星候选者的IRAS样本，在45个天体中有17个探测到了3.3微米的发射。我们将这些天体确定为比HerBig Ae/Be恒星略年轻的恒星。许多这样的恒星似乎显示出3.3微米的辐射。我们还计划在近红外图像中寻找具有冰层吸收和3.3微米发射的年轻恒星物体的特征。

Development of a cryogenic infrared camera to probe the 3.3 micron emission over the Galactic plane is underway. A Ritchey-Chretien optics system of the primary (25 cm in diameter) and secondary mirrors has been proved to have good optical quality. It has been installed in a cryostat with an InSb 256X256 array, and we have obtained infrared images with them. The electronics was tuned so that optimum operation is achieved under fairly strong background radiation. Observation of the Galactic plane with this system will be started this year.Infrared imaging and spectroscopy of individual star forming regions in the Galaxy has been made to investigate the evolutionary stages when the star forming region radiates the 3.3 micron emission. In S140, its infrared source IRS1 has conspicuous ice absorption at 3.1 microns, and polarization changes across the absorption band. However, it has no 3.3 micron emission, which might mean that this object is too young to emit the 3.3 micron emission. We also searched a IRAS sample of young stellar candidates, and detected the 3.3 micron emission in 17 out of 45 objects. We identify these objects as slightly younger stars than the Herbig Ae/Be stars. Many of such stars seem to show the 3.3 micron emission. We also plan to search for features of young stellar objects with the ice absorption and with the 3.3 micron emission in near infrared images.