The mid-infrared bubble Sh2-90: a possible case of triggered star formation?
M. R. Samal

Aryabhatta Research Institute of Observational Sciences, Nainital 263129, India

Abstract. We analyze the distribution of the young sources and interstellar matter in the environs of the mid-infrared (MIR) bubble coincides with the &hii; region Sh 2-90. Our study is based on the radio continuum mapping at 1280 MHz, along with Spitzer-IRAC and near-infrared (NIR) data. We performed the photometric analysis at NIR-MIR bands to assess the likely stellar candidates with disk and envelope using colour-colour (CC) diagrams. The morphology suggests a 8 μm void at the center of the $hii region. However, we see roughly circular shell of 8 μm emission enclosing the ionized gas seen in 1280 MHz, indicating void is probably originated due to the energy input from a massive source. Our study shows that the massive star is possibly a O9-B0 type. From the photometric analyses, we find a group of young stellar objects (YSOs) at the border of the bubble. Our preliminary analysis suggets that Sh2-90 shows signature for a possible site of triggered star formation.

Key words: stars -- formation -- pre-main-sequence: ISM -- &hii;