Mathematics – Probability
Scientific paper
May 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997ycat..20690099s&link_type=abstract
VizieR On-line Data Catalog: J/ApJS/69/99. Originally published in: 1989ApJS...69...99S
Mathematics
Probability
Clusters: Open, Supernova Remnants, Photometry: Infrared
Scientific paper
We present near-infrared observations of specific sites of high-mass star formation activity in the giant H II region/molecular cloud complex NGC 6334. The observations consist of high-spatial resolution broad-band imaging, chopping photometry, and moderate-resolution spectra. The imaging observations provide full spatial sampling of the stellar population over a significant area of the cloud to a limit of K=13.5mag and reveal many faint red sources around the sites of recent high-mass star formation. We show that most of these sources are associated with the NGC 6334 molecular cloud and are not Galactic field sources. In the majority of the regions the embedded sources are primarily reddened main-sequence stars of low and intermediate mass though in three of the 11 regions studied there is a high proportion of objects showing H-K excesses which are therefore probably pre main-sequence. We identify the red objects in FIR-I as belonging to a very young compact cluster of ~1pc spatial extent. In FIR-V an unexpectedly large number of bright red sources are detected which have CO absorption at 2.3μm. The probability that these objects are Galactic field sources is very low and if they are giant stars associated with NGC 6334 their implied ages (>109yr) are inconsistent with the many indicators of extreme youth in this region. We propose that they form a hitherto unrecognized population of high-luminosity pre-main-sequence objects. Two objects with similar characteristics are also found in images of an area of the NGC 6334 molecular cloud to the north of FIR-V (SH-1). In FIR-V we also find evidence that the molecular outflow from the already known high-mass protostar has triggered intermediate-mass star formation via interaction with the local interstellar medium. Mass functions have been derived for the embedded stellar aggregates under the assumption that all sources lie on the main sequence unless otherwise indicated. The effect of a population of pre-main-sequence objects on the derived mass function slopes is shown to be small. Embedded aggregates in NGC 6334 have stellar mass distributions similar to those found both in young visible clusters and in other embedded clusters. This suggests that the slope of the mass function is relatively insensitive to conditions in the star formation environment and that the solar neighborhood value applies to star formation regions on scales as small as 1pc and of ages less than 107yr. (2 data files).
Hyland A. R.
McGregor Peter J.
Straw Steven M.
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