PoS(LCDU 2013)126 Evolution of Planetary Nebulae and PAH features Ryou Ohsawa * a , Takashi Onaka a , Itsuki Sakon a , Tamami I. Mori a , Issei Yamamura b , Mikako Matsuura c , Hidehiro Kaneda d , Jeronimo Bernard-Salas e , Olivier Berné f , and Christine Joblin f Graduate School of Science, University of Tokyo, 113-0033 Tokyo, Japan a ISAS/JAXA, 252-5210 Kanagawa, Japan b University College London, Gower St, London WC1E 6BT, United Kingdom c Nagoya University, 466-8550 Aichi, Japan d Open University, Walton Hall, Milton Keynes, Buckinghamshire MK7 6AA, United Kingdom e IRAP Université de Toulouse & CNRS, 9, Av. du Colonel Roche BP 44346 F-31028 Toulouse Cedex 4, France f E-mail: ohsawa@astron.s.u-tokyo.ac.jp Near- to mid-infrared spectra of 17 Galactic Planetary Nebulae (PNe), which show prominent C-rich dust features, were obtained with the AKARI /IRC and Spitzer/IRS. Relative intensities of Polycyclic Aromatic Hydrocarbon (PAH) features were measured. The evolutionary stage of PNe is estimated by the effective temperature of the central star. The evolution of the PAH emission is investigated in terms of the evolution of the central stars. As PNe evolve, the ionization fraction of PAHs decreases, the 3.4–3.5 μ m aliphatic features become stronger and the peak position of the 6.2 μ m feature moves toward shorter wavelengths. Possible mechanisms for the evolution of the PAH emission are discussed. The Life Cycle of Dust in the Universe: Observations, Theory, and Laboratory Experiments - LCDU 2013, 18-22 November 2013 Taipei, Taiwan * Speaker. c ⃝ Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/