Warm dust around blue hypergiants: mid-infrared imaging of the luminous blue variable HD 168625

摘要

We present the first high spatial resolution images of thermal emission from the nebula surrounding the Galactic luminous blue variable (LBV)HD 168625. Four images, centered at 4.7, 10.1, 11.6, and 19.9 μm, have been obtained at UKIRT with MAX, the new mid-IR camera of the Max-Planck-Institut fur Astronomie. A Brγ image taken at UKIRT with IRCAM3 is also presented. On the basis of the available spectrophotometric data and of or photometry of the central star, we revise the distance currently Assumed for this source from 2.2 to 1.2 kpc. The dust emission, which is optically thin and therefore Sensitive to the mass distribution, clearly indicates the bipolar structure of the nebula.