A study of the bipolar nebula associated with LKHɑ208

Abstract

An investigation of the nebulosity illuminated by the star LKHɑ208 has been carried out. Observations of the nebulosity were made in four colours. These were used in conjunction with linear polarization measurements for the object to investigate the detailed structure of the nebula. Numerical modelling of the nebulosity has been carried out. it has been shown that the observations result from the scattering of radiation by dust which is concentrated at the edges of a cavity, the structure of which may be approximated by a paraboloid. The grains comprising the nebula are of high albedo ( > 0.8) and low refractive index (1.25 (^±) 0.12). It is proposed that icy grain mantles are present in the dust, so yielding these results. The dust grain size distribution takes the form of a power-law distribution such that n(a) = a(^-4.3) where n(a)da is the number density of particles with radii in the range (a, a+da).