Dust Color Temperature and Planck Function Distribution of a Far Infrared Planetary Nebula at 90 and 140 μm AKARI Map

We performed a study of dust color temperature and Planck function distribution of a far-infrared (FIR) planetary nebula structure (90 μm and 140 μm) under the AKARI (infrared astronomy satellite developed by Japan Aerospace Exploration Agency) survey. An interesting nebular structure (major diameter ~ 1.57 pc and minor diameter ~ 1.38 pc) is found to lie at galactic longitude 67.907° and latitude -0.249°, located at a distance ~1.7 kpc was selected for the study. 0.5°×0.5° AKARI all-sky map of a structure was downloaded from Sky View Virtual Observatory (https://skyview.gsfc.nasa.gov/) and then processed in the software ALADIN v2.503. The dust color temperature was found to lie in the range 16.99 K to 37.36 K. We found an offset of about 20 K which indicates that our structure is not independently evolved, or for the structure shaping mechanism, the role of discrete point sources in the field of the nebula is important. We also studied the distribution of dust color temperature and Planck function along major and minor diameters. In major diameter, particles were found to be oscillating sinusoidally. This suggests that particles are not in thermal equilibrium and they are oscillating sinusoidally to get dynamical equilibrium. In minor diameter, temperature and Planck function was noticed to be linearly decreased. Further, the far-infrared spectral distribution of the structure was studied. The negative slope in the transition from 65 µm to 160 µm was noticed in the FIR spectral distribution of the nebula structure. Decreasing spectral distribution advocates the decrease in the number density of dust particles.