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Astron. Astrophys. 361, L29-L32 (2000)

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Letter to the Editor

Diffraction-limited bispectrum speckle interferometry and speckle polarimetry of the young bipolar outflow source S140 IRS1

D. Schertl 1, Y. Balega 2, T. Hannemann 1, K.-H. Hofmann 1, Th. Preibisch 1 and G. Weigelt 1

1 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
2 Special Astrophysical Observatory, Nizhnij Arkhyz, Zelenchuk region, Karachai-Cherkesia, 357147, Russia

Received 21 July 2000 / Accepted 15 August 2000


We present bispectrum speckle interferometry and speckle polarimetry of the deeply embedded infrared bipolar outflow source S140 IRS1, a massive protostellar object in the L1204 molecular cloud. Using the SAO 6 m telescope, we obtained 280 mas resolution polarization maps of S140 IRS1 as well as a K-band image with diffraction-limited resolution [FORMULA]/D of 76 mas, which is the highest angular resolution image of a young outflow source ever obtained in the infrared. Our data suggest that the central source is marginally resolved with a FWHM diameter of approximately 20 mas ([FORMULA] AU). The most remarkable feature in our image 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. A centro-symmetric pattern of high polarization in this feature suggests that we see scattered light from the central source. 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.

Key words: techniques: interferometric – stars: individual: S140 IRS1 – stars: formation – stars: winds, outflows

Send offprint requests to: ds@mpifr-bonn.mpg.de

© European Southern Observatory (ESO) 2000

Online publication: October 2, 2000