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MPIfR Optical & Infrared Interferometry Group

Preibisch, T., Balega, Y., Schertl, D., Hofmann, K.-H., and Weigelt, G.

Bispectrum 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 (2003)

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.
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