Distribution of the 3.3 micrometer Emission Band in the Galaxy

目前正在研制一种低温红外照相机，以探测银河平面上方的3.3微米辐射。由主镜（直径25厘米）和次镜组成的里奇-克雷蒂安光学系统已被证明具有良好的光学质量。它已被安装在低温恒温器与InSb 256 × 256阵列，我们已经获得了红外图像。电子设备经过调整，以便在相当强的背景辐射下实现最佳操作。今年将开始用该系统观测银道面，并对银河系中个别星星形成区进行红外成像和光谱学研究，以探讨星星形成区辐射3.3微米辐射时的演化阶段。在S140中，其红外源IRS 1在3.1微米处具有明显的冰吸收，并且偏振在吸收带上变化。然而，它没有3.3微米的辐射，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，并在45个对象中的17个中检测到3.3微米的发射。我们认为这些天体比Herbig Ae/Be恒星稍年轻。许多这样的恒星似乎显示出3.3微米的发射。我们还计划在近红外图像中寻找具有冰吸收和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.