Concurrent Formation of Carbon and Silicate Dust in Nova V1280 Sco

Itsuki Sakon, Shigeyuki Sako, Takashi Onaka, Takaya Nozawa, Yuki Kimura, Takuya Fujiyoshi, Takashi Shimonishi, Fumihiko Usui, Hidenori Takahashi, Ryou Ohsawa, Akira Arai, Makoto Uemura, Takahiro Nagayama, Bon-Chul Koo & Takashi Kozasa

University of Tokyo, Japan

We have carried out infrared multi-epoch observations of the dust forming nova V1280 Sco over ~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)x10-8 solar mass with a representative grain size of 0.01 mm and astronomical silicate dust of mass (3.4-4.3)x10-7 solar mass with a representative grain size of 0.3-0.5 mm. Both of carbon and silicate dust 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. Cool clumpy clouds produced via interactions between the pre-existing circumstellar gas and high velocity nova ejecta may have provided a favorable condition for the silicate dust to attain a large grain size.

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