Abstract
We present a large-scale study of the IC1396 region using new deep NIR and optical images, complemented by 2MASS data. For ten globules in IC1396 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 (HH865 and HH864) 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 HD206267. 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 HD206267 has a major impact on the star formation activity in these globules.
Highlights
Star formation takes place in giant molecular clouds and in small isolated globules
near infrared (NIR) observations of IC 1396 in conjunction with extinction maps obtained from 2MASS data reveal star forming activity and a large number of globules in this region
Four of them were previously uncatalogued in the SIMBAD database
Summary
Star formation takes place in giant molecular clouds and in small isolated globules. The identification of young stellar clusters or outflow activity in such globules hints an ongoing star formation process. Star formation in globules might be induced by the propagation of an ionisation shock front, the so-called radiation driven implosion mechanism (Reipurth 1983). It is not fully clear what the main properties are that influence star formation within these globules (e.g. density, mass, or size of the globule, strength of the ionisation shock front). The investigation of a larger, homogeneous, and as far as possible unbiased sample of globules is an ideal way to obtain a deeper understanding of these issues
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