A Census of Dust Components in the Galactic Centre

A.J.Adamson1, R.E.Mason2, G.S.Wright2, J.E.Chiar3, Y.Pendleton3, T.H.Kerr1, D.C.B.Whittet4, M.G.Rawlings5, J.E.Bowey6

1 Joint Astronomy Centre, Hilo Hawaii
2 UKATC, Edinburgh
3 NASA Ames Research Center
4 Rensselaer Polytechnic Institute
5 University of Helsinki
6 University College London

E-mail contact: adamson@jach.hawaii.edu

The Galactic Centre offers a uniquely valuable line of sight for studies of the nature of dust in the ISM, but the traditional assumption that the line of sight samples only the diffuse ISM has been subverted by ISO observations demonstrating the presence of molecular absorption bands in the field. As reported elsewhere in these proceedings, our own UKIRT spectroscopy also shows that the diffuse-medium hydrocarbon absorptions are quite variable across the field, and this variation was used to produce truly independent spectra of the ice and hydrocarbon absorption features. The variability of the observed features suggests a patchy distribution even of the foreground diffuse absorbers. To map this clumpy distribution and to produce an inventory of the dust components, we have carried out a narrow-band imaging survey of the Galactic Centre field out to and including the circumnuclear ring, using both IRCAM and Michelle on UKIRT to cover the 3-micron water ice, 3.3-micron PAH, 3.4-micron hydrocarbon and 9.7-micron silicate absorption features. This poster reports on progress with analysis of the survey data.