The Formation of Bimodal Dust Species in Nova Ejecta

• Published in: Publications of the Astronomical Society of the Pacific Vol. 131; no. 1006; pp. 124202 - 124208
• Main Authors: Duolikun, Adili, Zhu, Chunhua, Wang, Zhaojun, Liu, Helei, Li, Lin, Liu, Jinzhong, Lü, Guoliang
• Format: Journal Article
• Language: English
• Published: Philadelphia The Astronomical Society of the Pacific 01.12.2019; IOP Publishing
• Subjects: Astrophysics; binaries: close; Chemical properties; Dust; dust, extinction; Eruptions; novae, cataclysmic variables
• ISSN: 0004-6280; 1538-3873
• DOI: 10.1088/1538-3873/ab45dd

The formation of bimodal dust species (namely the silicate and amorphous carbon dust grains coexistent) in a nova eruption is an open problem. According to the nova model simulated by Modules for Experiments in Stellar Astrophysics code, we calculate the formation and growth of carbon (C) and forsterite (Mg2SiO4) dust grains purely in nova ejecta for the fee-expansion model and the radiative shock model by assuming spherical geometry of the nova ejecta. In these models, the chemical properties of pre-existing circumstellar medium are not taken into account. In the free-expansion model, the nova ejecta is not an idea environment for dust nucleation. However, it can efficiently produce dust in the radiative shock model. We estimate that every nova can produce C grains with an average mass of about 10−9 and 10−8 M , and Mg2SiO4 grains with an average mass of about 10−8 and 10−7 M . Based on the mass of ejected gas, the ratio of dust to gas is about 1%. The C grains form first after several or tens of days of nova eruption. After that, the Mg2SiO4 grains begin to grow in tens of days, which is consistent with observations.