Proceedings of the International Astronomical Union

Table of Contents - June 2011 - Volume 7, Symposium S280 (The Molecular Universe)  

Contributed Papers

The PAH Hypothesis after 25 Years

Els Peetersa1a2

a1 Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7, Canada email: epeeters@uwo.ca

a2 SETI Institute, 189 Bernardo Ave., Suite 100, Mountain View, CA 94043, USA email: epeeters@seti.org

Abstract

The infrared spectra of many galactic and extragalactic objects are dominated by emission features at 3.3, 6.2, 7.7, 8.6 and 11.2 μm. The carriers of these features remained a mystery for almost a decade, hence the bands were dubbed the unidentified infrared (UIR) bands. Since the mid-80's, the UIR bands are generally attributed to the IR fluorescence of Polycyclic Aromatic Hydrocarbon molecules (PAHs) upon absorption of UV photons – the PAH hypothesis. Here we review the progress made over the past 25 years in understanding the UIR bands and their carriers.

Keywords

  • infrared emission features;
  • ISM: molecules;
  • ISM: lines and bands;
  • (stars:) circumstellar matter;
  • infrared: general;
  • astrochemistry;
  • techniques: spectroscopic