AFGL 5157 NH_3 : a new stellar cluster in the forming process

We present the analysis of Spitzer/IRAC and near infrared imaging obser- vation of AFGL 5157, an active star forming region. In the IRAC images, this region shows strong emissions of polycyclic aromatic hydrocarbons in channel 4 and emis- sions of H2 in channel 2. Many of the H2 features are aligned to form jet-like struc- tures. Three bipolar jets in the NHa core region and a couple of jets northwest of the core have been identified. We identify the possible driving agents of the bipolar jets and show them to be very young. An embedded cluster has been detected in the NH3 core; many members in the cluster have spectral energy distributions that increase from JHK bands toward longer wavelengths, indicative of their early evolutionary stages. Millimeter and submillimeter continuum emissions in the NH3 core and the northwest subregion are found to coincide spatially with these presumable Class0/I sources. The existence of H2 bipolar jets and very young stellar objects suggests that star formation is continuing at the present epoch in these subregions. Combining in- formation from previous studies, we propose a sequential star formation scenario in the whole AFGL 5157 region.

MWA5121 MWA5157 通用宽带集成放大器

MWA 5121和MWA 5157是美国莫托洛拉(MOTOROLA)公司近年来研制出的新型超高频宽带放大器集成电路,具有频带宽、增益高、噪声低、互调失真小、线性范围大、输出电平高等特点。适用于设计制作简易卫星信号的接收、远程电视接收的天线放大器以及共用天线电视系统中的天线频道、线路和高频信号放大等线路,是一种比较理想的通用宽带集成放大器。图1是MWA5121、MWA5157管脚功能图。

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