2020/07/30 by Keiichi Wada, Yusuke Tsukamoto, Eiichiro Kokubo · 1 voice · 3 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.3847/1538-4357/abd40a
Abstract In Wada et al. (2019), we proposed for the first time that a new class of planets, blanets , can be formed around supermassive black holes in the galactic center. Here, we investigate the dust coagulation processes and physical conditions of the blanet formation outside the snowline ( r snow ∼ several parsecs) in more detail, especially considering the effect of the radial drift of the dust aggregates. We found that a dimensionless parameter , where v t is the turbulent velocity and c s is the sound velocity, describing the turbulent viscosity should be smaller than 0.04 in the circumnuclear disk to prevent the destruction of the aggregates due to collision. The formation timescale of blanets τ GI at r snow is, τ GI ≃ 70–80 Myr for α = 0.01 − 0.04 and M BH = 10 6 M ⊙ . The mass of the blanets ranges from ∼20 M E to 3000 M E in r < 4 pc for α = 0.02 ( M E is the Earth mass), which is in contrast with 4 M E –6 M E for the case without the radial drift. Our results suggest that blanets could be formed around relatively low-luminosity active galactic nuclei ( L bol ∼ 10 42 erg s −1 ) during their lifetime (≲10 8 yr).