On the massive young stellar object AFGL 4176

High-spatial-resolution multi-wavelength observations and modeling

¹ Max Planck Institute for Astronomy, Königstuhl 17, Heidelberg, Germany
e-mail: boley@mpia.de; linz@mpia.de; boekel@mpia.de; bouwman@mpia.de; henning@mpia.de
² Ural Federal University, Astronomical Observatory, 51 pr. Lenina, Ekaterinburg, Russia
e-mail: andrey.sobolev@usu.ru

Received: 30 January 2012
Accepted: 12 September 2012

Abstract

Deeply embedded and at distances of several kiloparsecs, massive young stellar objects (MYSOs) present numerous challenges for observation and study. In this work, we present spatially-resolved observations of one MYSO, AFGL 4176, together with survey and literature data, ranging from interferometric observations with VLTI/MIDI in the mid-infrared, to single-dish Herschel measurements in the far-infrared, and sub-millimeter data from APEX. We consider this spatially-resolved, multi-wavelength data set in terms of both radiative transfer and geometric models. We find that the observations are well described by one-dimensional models overall, but there are also substantial deviations from spherical symmetry at scales of tens to hundreds of astronomical units, which are revealed by the mid-infrared interferometric measurements. We use a multiple-component, geometric modeling approach to explain the mid-infrared emission on scales of tens to hundreds of astronomical units, and find the MIDI measurements are well described by a model consisting of a one-dimensional Gaussian halo and an inclined (θ = 60°) circumstellar disk extending out to several hundred astronomical units along a position angle of 160°. Finally, we compare our results both with previous models of this source, and with those of other MYSOs, and discuss the present situation with mid-infrared interferometric observations of massive stars.