Star formation in globules in IC 1396

Abstract

We present a large-scale study of the <ns0:ext-link ext-link-type="aoi">IC 1396</ns0:ext-link> region using new deep NIR and optical images, complemented by 2MASS data. For ten globules in <ns0:ext-link ext-link-type="aoi">IC 1396</ns0:ext-link> we determine ($H-K$, $J-H$) colour–colour diagrams and identify the young stellar population. Five of these globules contain a rich population of reddened objects, most of them probably young stellar objects. Two new HH objects (<ns0:ext-link ext-link-type="aoi">HH 865</ns0:ext-link> and <ns0:ext-link ext-link-type="aoi">HH 864</ns0:ext-link>) could be identified by means of [SII] emission, one of them a parsec-scale flow. Using star counts based on 2MASS data we create an extinction map of the whole region. This map is used to identify 25 globules and to estimate their mass. The globule masses show a significant increase with the distance from the exciting O6.5V star <ns0:ext-link ext-link-type="aoi">HD 206267</ns0:ext-link>. We explain this correlation by the enhanced radiation pressure close to this star, leading to evaporation of the nearby clouds and hence smaller globule masses. We see evidence that the radiation from <ns0:ext-link ext-link-type="aoi">HD 206267</ns0:ext-link> has a major impact on the star formation activity in these globules.