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Astron. Astrophys. 346, 243-259 (1999)

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High-resolution imaging of ultracompact H II regions

II. G5.89-0.39 revisited *

M. Feldt 1, B. Stecklum 2, Th. Henning 1, R. Launhardt 3 and T.L. Hayward 4

1 Astrophysikalisches Institut und Universitäts-Sternwarte (AIU), Schillergässchen 2-3, D-07745 Jena, Germany
2 Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany
3 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
4 Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853, USA

Received 3 December 1998 / Accepted 3 February 1999

Abstract

We present the results of an extensive imaging campaign on the ultracompact HII region G5.89-0.39 at near- and mid-infrared wavelengths. High-resolution data were taken in the H, [FORMULA], and L bands using ESO's adaptive optics system ADONIS. They are complemented by conventional narrow-band images in Br[FORMULA] and [FORMULA] as well as by mid-infrared broad- and narrow-band images. We also mapped the 1.3 mm continuum emission from the source using the SEST.

We use our data to consistently explain the morphological appearance of G5.89-0.39 at all observed wavelengths as well as its spectral energy distribution. The complete model of the source consists of a spherical shell of dust with an inner, dust-free cavity of 7.6[FORMULA] cm radius surrounding a star of spectral type O6 ZAMS. Two outflows escape this shell in opposite directions. Half of the whole configuration is evidently obscured by a very massive cloud of cold dust. Comparisons with earlier models and other ultracompact HII regions are drawn to put G5.89-0.39 in the context of massive star formation.

Key words: stars: formation – stars: early-type – ISM: H ii regions – methods: observational

* Based on observations collected at the European Southern Observatory, La Silla, Chile

Send offprint requests to: M. Feldt (mfeldt@mpia-hd.mpg.de)

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© European Southern Observatory (ESO) 1999

Online publication: May 6, 1999
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