Abstract (Expand)
We performed numerical simulations of the common envelope (CE) interaction between thermally-pulsing asymptotic giant branch (AGB) stars of 1.7 M⊙ and 3.7 M⊙, respectively, and a 0.6 M⊙ compact companion. … We use tabulated equations of state to take into account recombination energy. For the first time, formation and growth of dust is calculated explicitly, using a carbon dust nucleation network with a C/O abundance ratio of 2.5 (by number). The first dust grains appear within ∼1–3 yrs after the onset of the CE, forming an optically thick shell at ∼10–20 au, growing in thickness and radius to values of ∼400–500 au over ∼40 yrs, with temperatures around 400 K. Most dust is formed in unbound material, having little effect on mass ejection or orbital evolution. By the end of the simulations, the total dust yield is ∼8.4 × 10−3 M⊙ and ∼2.2 × 10−2 M⊙ for the CE with a 1.7 M⊙ and a 3.7 M⊙ AGB star, respectively, corresponding to a nucleation efficiency close to 100%, if no dust destruction mechanism is considered. Despite comparable dust yields to single AGB stars, in CE ejections the dust forms a thousand times faster, over tens of years as opposed to tens of thousands of years. This rapid dust formation may account for the shift in the infrared of the spectral energy distribution of some optical transients known as luminous red novae. Simulated dusty CEs support the idea that extreme carbon stars and ‘water fountains’ may be objects observed after a CE event.
Authors: Luis C Bermúdez-Bustamante, Orsola De Marco, Lionel Siess, Daniel J Price, Miguel González-Bolívar, Mike Y M Lau, Chunliang Mu, Ryosuke Hirai, Taïssa Danilovich, Mansi M Kasliwal
Date Published: 30th Jul 2024
Publication Type: Journal
Germany
https://orcid.org/0000-0002-6592-2036 
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