Discovery of an extended infrared reflection nebula around S106

• Published in: Monthly notices of the Royal Astronomical Society 1987-03, Vol.225 (2), p.393-398
• Main Authors: McLean, I. S., McCaughrean, M. J., Gatley, I., Hough, J., Sato, S., Nagata, T., Axon, D., Burton, M. G., Garden, R., Aspin, C., Hasegawa, T., Hayashi, M., Morimoto, M., Kaifu, N.
• Format: Article
• Language: English
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; H ii regions. Emission and reflection nebulae; Interstellar medium (ism) and nebulae in milky way; Stellar systems. Galactic and extragalactic objects and systems. The universe
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/225.2.393

An extensive, low surface brightness reflection nebula has been discovered around S106 by mapping the infrared polarization at 2.2 μm. Polarized flux is detected to almost 3 arcmin from the central source (IRS4), well beyond the main part of the optical H n nebula. The pattern of polarization vectors is centro-symmetric about the embedded object and is a characteristic of a reflection nebula. Polarizations as large as 25 per cent are observed, with the remarkable result that there is no obvious anomaly in the distribution of 2.2 μm polarization corresponding to the optical bipolar morphology. This difference can be explained by a simple model involving a compact dust disc near the embedded star. We also discuss the implications of this detection as an important new tracer of the extent of dust, and for the significant role that scattering from grains may play in protostellar clouds and obscured bipolar flows.