Near-infrared polarization images of the Orion proplyds^*

¹ I. Physikalisches Institut, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany e-mail: rost@ph1.uni-koeln.de
² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
³ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr., 85748 Garching, Germany

Received: 27 March 2007
Accepted: 27 March 2008

Abstract

Aims. The aim is to study structure and polarization properties of the stars and planet systems in the active Orion -region.

Methods. We performed AO-assisted high-resolution imaging polarimetry on selected Orion proplyds close to the Trapezium stars in the J, H, and K bands. Differential polarimetric images of one of the largest and brightest proplyds are interpreted using 3D radiation transfer simulations based on the Monte Carlo method.

Results. Although not fully resolvable by ground-based observations, the circumstellar material can be mapped with polarimetry. We present constraints on the disk parameters of the giant proplyd 177-341. We tested whether dust models with different grain size distributions could explain the observed extent of the polarization patterns and find that simple models with larger grains will not reproduce the spectral polarization behavior.

Conclusions. The technique of polarimetric differential imaging (PDI) in the NIR provides a good opportunity to study the structure of the Orion proplyds.