Fragmentation of protoplanetary discs around M-dwarfs

• Published in: Monthly notices of the Royal Astronomical Society 2016-12, Vol.463 (3), p.2480-2480
• Main Authors: Backus, Isaac, Quinn, Thomas
• Format: Article
• Language: English
• Subjects: Clumps; Disks; Dwarf stars; Equilibrium; Fragmentation; Initial conditions; Mathematical models; Planet formation; Planetology; Protoplanetary disks; Protoplanets; Simulation
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stw1825

We investigate the conditions required for planet formation via gravitational instability (GI) and protoplanetary disc (PPD) fragmentation around M-dwarfs. Using a suite of 64 SPH simulations with 10 super( 6) particles, the parameter space of disc mass, temperature, and radius is explored, bracketing reasonable values based on theory and observation. Our model consists of an equilibrium, gaseous, and locally isothermal disc orbiting a central star of mass M... Discs with a minimum Toomre Q of ... will fragment and form gravitationally bound clumps. Some previous literature has found Q sub( min) < 1.3-1.5 to be sufficient for fragmentation. Increasing disc height tends to stabilize discs, and when incorporated into Q as ... for alpha = 0.18 is sufficient to predict fragmentation. Some discrepancies in the literature regarding Q sub( crit) may be due to different methods of generating initial conditions (ICs). A series of 15 simulations demonstrates that perturbing ICs slightly out of equilibrium can cause discs to fragment for higher Q. Our method for generating ICs is presented in detail. We argue that GI likely plays a role in PPDs around M-dwarfs and that disc fragmentation at large radii is a plausible outcome for these discs. (ProQuest: ... denotes formulae/symbols omitted.)