CONCURRENT FORMATION OF CARBON AND SILICATE DUST IN NOVA V1280 SCO

We present infrared multi-epoch observations of the dust forming nova V1280 Sco over $\sim$2000 days from the outburst. The temporal evolution of the infrared spectral energy distributions at 1272, 1616 and 1947 days can be explained by the emissions produced by amorphous carbon dust of mass (6.6--8.7)$\times$10$^{-8}$M$_{\odot}$ with a representative grain size of 0.01$~\mu$m and astronomical silicate dust of mass (3.4--4.3)$\times$10$^{-7}$M$_{\odot}$ with a representative grain size of 0.3--0.5$~\mu$m. Both of these dust species travel farther away from the white dwarf without an apparent mass evolution throughout those later epochs. The dust formation scenario around V1280 Sco suggested from our analyses is that the amorphous carbon dust is formed in the nova ejecta followed by the formation of silicate dust in the expanding nova ejecta or as a result of the interaction between the nova wind and the circumstellar medium.