Infrared portrait of the nearby massive star-forming region IRAS 09002-4732

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany e-mail: apai@as.arizona.edu
² Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721, USA
³ NASA Astrobiology Institute
⁴ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany

Received: 17 December 2003
Accepted: 10 December 2004

Abstract

We present high-resolution near-infrared and mid-infrared imaging, mid-infrared spectroscopy and millimetre-wavelength continuum observations of the nearby massive star-forming complex IRAS 09002-4732. A rich cluster of young stars displaying near-infrared excess emission is detected. We identify the ionising source of the ultracompact H II region G268.42-0.85 and show that this star is the dominant heating and illuminating source of the region. Spectral type estimates based on different methods are consistent with a star of spectral type O9. The combination of the new observations with literature data allows us to set up the first structural model for the region. We argue that the ultracompact H II region is embedded in the rear side of the southern CS clump. Additionally, we detect several interesting objects. Among these objects are a network of dark dust filaments, an elongated, externally heated object with strong infrared excess inside the H II region and objects seen as silhouettes in the foreground of the large southern reflection nebulosity. The filamentary structures may play an important role in the star formation process.