Star Formation in Bok Globules: Near-Infrared Survey of a Southern Sky Sample

N. C. Santos, J. L. Yun, C. A. Santos, R. G. Marreiros
<span title="">1998</span> <i title="IOP Publishing"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/24u4x3hwkvb5befybykrphkbti" style="color: black;">Astronomical Journal</a> </i> &nbsp;
We performed a near-infrared imaging survey toward 23 Bok globules in the southern sky containing IRAS point sources. Visual examination of the images revealed that 15 globules showed evidence of nebular emission or very red stellar objects located at the position of the sources. Analysis of the nearinfrared nebulosities present in the images revealed that (1) these nebulosities generally contain one or more stellar-like sources surrounded by a more or less extended component ; (2) a couple of
more &raquo; ... ossible binaries with separations of about 4A were found to reside in common infrared nebulosity ; (3) infrared reÑection nebulae, seen at 2.2 km, are usually associated with class I sources. The nature of the southern sky sample of Bok globules seems to be similar to that of the northern sample of globules, with similar star formation properties : they tend to form a single or a few stars, and in some cases, they seem to be lodging small aggregates of young stellar objects. We conÐrm that, in general, the value of the 12/25 km spectral index is a good indicator of the evolutionary stage of a young stellar object. Large negative 12/25 km indices seem to indicate younger objects deeply embedded in their clouds (by showing nebulosities mostly in the K band, having associated molecular outÑows, and no optical counterparts). As these objects reach later stages of their preÈmain-sequence evolution (becoming optically visible), their 12/25 km indices increase and become positive.
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