Peering into the heart of a high-mass star forming region: Bispectrum speckle interferometry of the ultracompact H II region K3-50 A^*

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

Corresponding author: T. Preibisch, preib@mpifr-bonn.mpg.de

Received: 5 November 2003
Accepted: 24 December 2003

Abstract

We present K'-band bispectrum speckle interferometry of the ultracompact H II region K3-50A. Our image resolves the central region into at least 7 point-like objects. We find K'-band counterparts for all but one of the N-band sources discovered by Okamoto et al. ([CITE]), and there are additional K'-band sources which were unresolved in the N-band images. Our reconstructed image also reveals the fine-structure of the cone-shaped nebulosity extending to the south. The brightest K'-band source is located exactly at the tip of the cone-shaped nebulosity. The nebula shows several arcs and the orientation of its main axis agrees very well with the direction of the CO outflow from K3-50A. This nebulosity therefore very likely represents the clumpy inner surface of a partially evacuated cavity excavated by the strong outflows.