Primordial Obliquities of Brown Dwarfs and Super-Jupiters from Fragmenting Gravito-Turbulent Discs

Abstract

Super-Jupiters, brown dwarfs, and stars can form from the collapse of self-gravitating discs. Such discs are turbulent, with flocculent spiral arms accelerating gas to transonic speeds horizontally and vertically. Objects that fragment from gravito-turbulent discs should spin with a wide range of directions, reflecting the random orientations of their parent eddies. We show by direct numerical simulation that obliquities of newly collapsed fragments can range up to 45${}^{\circ }$. Subsequent collisions between fragments can further alter the obliquity distribution, up to 90${}^{\circ }$ or down to near-zero. The large obliquities of newly discovered super-Jupiters on wide orbits around young stars may be gravito-turbulent in origin. Obliquely spinning fragments are born on orbits that may be inclined relative to their parent discs by up to 20${}^{\circ }$, and gravitationally stir leftover material to many times the pre-fragmentation disc thickness.

9 pages, 7 figures. Accepted to MNRAS

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Cited by in corpus (6)

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• Non-Trivial Oblique Spin Equilibria of Super-Earths in Multi-planetary Systems
• The case of HD 106906 debris disc: A binary's revenge
• Formation History of HD106906 and the Vertical Warping of Debris Disks by an External Inclined Companion
• Prograde spin-up during gravitational collapse
• Spin Dynamics of Extrasolar Giant Planets in Planet-Planet Scattering