Far-Infrared Luminous Supernova Remnant Kes 17
  We present the results of infrared (IR; 2.5--160 um) observations of the
supernova remnant (SNR) Kes 17 based on the data obtained with the AKARI and
Spitzer satellites. We first detect bright continuum emission of its western
shell in the mid- and far-IR wavebands together with its near-IR molecular line
emission. We also detect hidden mid-IR emission of its southern shell after
subtraction of the background emission in this region. The far-IR luminosity of
the western shell is ~ 8100 L_sun, which makes Kes 17 one of the few SNRs of
significant far-IR emission. The fittings of the spectral energy distribution
indicate the existence of two dust components: ~ 79 K (hot) and ~ 27 K (cold)
corresponding to the dust mass of ~ 6.2x10^{-4} M_sun and ~ 6.7 M_sun,
respectively. We suggest that the hot component represents the dust emission of
the material swept up by the SNR to its western and southern boundaries,
compatible with the distribution of radio continuum emission overlapping the
mid-IR emission in the western and southern shells. The existence of hot (~
2,000 K), shocked dense molecular gas revealed by the near-IR molecular line
emission in the western shell, on the other hand, suggests that the cold dust
component represents the dust emission related to the interaction between the
SNR and nearby molecular gas. The excitation conditions of the molecular gas
appear to be consistent with those from shocked, clumpy admixture gas of
different temperatures. We discuss three possibilities for the origin of the
bright far-IR emission of the cold dust in the western shell: the emission of
dust in the inter-clump medium of shocked molecular clouds, the emission of
dust in evaporating flows of molecular clouds engulfed by hot gas, and the
emission of dust of nearby molecular clouds illuminated by radiative shocks.
