Abstract We present the analysis of Spitzer/IRAC and near infrared imaging observation 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 emissions of H2 in channel 2. Many of the H2 features are aligned to form jet-like structures. Three bipolar jets in the NH3 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 Class 0/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 information from previous studies, we propose a sequential star formation scenario in the whole AFGL 5157 region.

Keywords ISM: individual (AFGL 5157) — ISM: jets and outflows — ISM: lines and bands— stars: formation

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