R. Sahai, M. R. Morris, M. J. Claussen
We report multi-wavelength observations of the far-infrared source IRAS
20324+4057, including high-resolution optical imaging with HST, and
ground-based near-infrared, millimeter-wave and radio observations. These data
show an extended, limb-brightened, tadpole-shaped nebula with a bright,
compact, cometary nebula located inside the tadpole head. Our molecular line
observations indicate that the Tadpole is predominantly molecular, with a total
gas mass exceeding 3.7 Msun. Our radio continuum imaging, and archival Spitzer
IRAC images, show the presence of additional tadpole-shaped objects in the
vicinity of IRAS 20324+4057 that share a common E-W head-tail orientation: we
propose that these structures are small, dense molecular cores that originated
in the Cygnus cloud and are now being (i) photoevaporated by the ultraviolet
radiation field of the Cyg OB2 No. 8 cluster located to the North-West, and
(ii) shaped by ram pressure of a distant wind source or sources located to the
West, blowing ablated and photoevaporated material from their heads eastwards.
The ripples in the tail of the Tadpole are interpreted in terms of
instabilities at the interface between the ambient wind and the dense medium of
the former.
View original:
http://arxiv.org/abs/1201.5067
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