EDP Sciences
Free access
Volume 432, Number 3, March IV 2005
Page(s) 895 - 908
Section Interstellar and circumstellar matter
DOI http://dx.doi.org/10.1051/0004-6361:20042094

A&A 432, 895-908 (2005)
DOI: 10.1051/0004-6361:20042094

Ultraviolet photoproduction of ISM dust

Laboratory characterisation and astrophysical relevance
E. Dartois1, G. M. Muñoz Caro1, D. Deboffle1, G. Montagnac2 and L. d'Hendecourt1

1  Institut d'Astrophysique Spatiale, UMR - 8617, Université Paris-Sud, Bâtiment 121, 91405 Orsay Cedex, France
    e-mail: emmanuel.dartois@ias.u-psud.fr
2  Laboratoire des Sciences de la Terre, UMR 5570 CNRS, École Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France

(Received 30 September 2004 / Accepted 30 October 2004 )

The production of a hydrogenated amorphous carbon polymer (a-C:H) via the photolysis of a series of organic molecule precursors at low temperature is described. Such amorphous material is synthesised under interstellar conditions (10 K and Lyman-$\alpha$ photons) and represents the best candidate to explain the Diffuse Interstellar Medium absorption observed in our Galaxy and in other galaxies. We perform a series of laboratory analyses (Infrared spectroscopy, $\mu$spectroscopy, Raman, Photoluminescence and UV-visible spectroscopy) which allow a full characterisation of such polymers. This allows us to assess the importance of the polymer and possible scenarios for its role in crucial aspects of the lifecycle of dust. Such material has implications for the carbon budget at galactic scales, hydrogen formation, extended red emission, as a PAH precursor, and in explaining the 2175 $\AA$ extinction bump.

Key words: ISM: dust, extinction -- galaxies: ISM -- ISM: lines and bands

© ESO 2005