MPIfR Optical & Infrared Interferometry Group
Preibisch, T., Balega, Y., Schertl, D., Hofmann, K.-H.,
and Weigelt, G.
speckle interferometry and future long-baseline interferometry of the young
bipolar outflow source S140 IRS1
in: W.A. Traub (ed.),
Interferometry for Optical Astronomy II, SPIE Conf. Vol. 4838
We present bispectrum speckle interferometric observations of the deeply embedded
protostellar outflow source S140 IRS1. Using the SAO 6 m telescope, we obtained
a K-band image with diffraction-limited resolution of 76 mas, which is the
highest resolution image of a young outflow source ever obtained in the infrared.
Our image shows the circumstellar environment of S140 IRS1 in unprecedented
detail and suggests that the central source is marginally resolved with a
FWHM diameter of approximately 20 mas (approx 20 AU). The dominant feature
is a bright extended and very clumpy structure pointing away from the central
source in exactly the same direction as the blue-shifted CO outflow lobe.
We interprete this feature as the clumpy inner surface of a partially evacuated
cavity in the circumstellar envelope around IRS1, which has been excavated
by the strong outflow from IRS1. In addition, we find several arc-like structures
north-east of IRS 1, extended diffuse emission south of IRS 1, and four new
point sources. The diffuse and fragmentary structures close to IRS 1 appear
to trace circumstellar material swept up by energetic outflows. In combination
with molecular line emission maps from the literature, our image provides
direct confirmation that two distinct bipolar outflow systems continue to
be driven from IRS 1 on scales between 3" and 100". Our speckle observations
provide important complementary information for future long-baseline interferometric
observations, for example with the LBT.