Radiatively driven Rayleigh-Taylor instabilities around a forming massive star system ? NACO adaptive optics and VISIR study of G333.6-0.2    [PDF]

M. S. N. Kumar
The formation of the highest mass stars are thought to be dominated by instabilities resulting from gravitation and radiation. Instabilities due to gravitation are commonly demonstrated by observations of fragmentation, but those due to effects of radiation are thus far not found. Here I report on the NACO adaptive optics and mid-infrared diffraction limited VISIR imaging data of an extemely luminous ultra-compact HII region G333.6-0.2. Two infrared sources, one bright in the near-infrared (appearing point-like) and another in the mid-infrared (resolved with an elliptical shape) are uncovered through this data, located at the heart of this region. These infrared sources appear to be embedded in the waist of a bipolar shaped nebula and UCHII region, the lobes of which are separated by a dark patch. It represents an outflow bubble originating from a large toroid viewed in its edge-on configuration. Filamentary features with finger/hook morphology are found connected to the two bright infrared sources which are {\em sharply limited} in size to $<$5000 AU. The observed properties and exhaustive data from the literature are compared with the results of various numerical simulations of high mass star formation. It favours the interpretation that the finger/hook like structures likely represent radiatively driven Rayleigh-Taylor instabilities arising in the outflow cavity of a forming high mass star binary system.
View original: http://arxiv.org/abs/1307.0437