Dynamical ejections of stars due to an accelerating gas filament

Abstract

Observations of the Orion A integral shaped filament (ISF) have shown indications of an oscillatory motion of the gas filament. This evidence is based on both the wavelike morphology of the filament as well as the kinematics of the gas and stars, where the characteristic velocities of the stars require a dynamical heating mechanism. As proposed by Stutz & Gould (2016), such a heating mechanism (the "Slingshot") may be the result of an oscillating gas filament in a gas-dominated (as opposed to stellarmass dominated) system. Here we test this hypothesis with the first stellar-dynamical simulations in which the stars are subjected to the influence of an oscillating cylindrical potential. The accelerating, cylindrical background potential is populated with a narrow distribution of stars. By coupling the potential to N-body dynamics, we are able to measure the influence of the potential on the stellar distribution. The simulations provide evidence that the slingshot mechanism can successfully reproduce several stringent observational constraints. These include the stellar spread (both in projected position and in velocity) around the filament, the symmetry in these distributions, and a bulk motion of the stars with respect to the filament. Using simple considerations we show that star-star interactions are incapable of reproducing these spreads on their own when properly accounting for the gas potential. Thus, properly accounting for the gas potential is essential for understanding the dynamical evolution of star forming filamentary systems in the era of Gaia.

A MODEST review

“…As the protostars evolve and become more compact, they progressively decouple from gas. When the decoupling occurs near the maximum of oscillation, where the acceleration is the highest, the protostar freely moves away from the filament, as confirmed by recent N -body simulations (Boekholt et al 2017).…”

Magnetic fields in star-forming systems (I): idealized synthetic signatures of dust polarization and Zeeman splitting in filaments

“…Here, r flat defines the characteristic radius of the density profile close to the center of the filament where the profile becomes flat and the parameter β controls the slope of the density at the outer regions. We apply a typical value in the order of r flat = 0.05, consistent with Palmeirim et al (2013), but see also Smith et al (2014Smith et al ( , 2016; Boekholt et al (2017) for the inference of a much smaller filament volume density profile inner softening scale. Although this Plummer profile differs from the density profile presented in Arzoumanian et al (2011) close to the center we use their average value of β = 1.6 as a tarting point, which is consistent with observations in the Intergral Shaped Filement (ISF) in Orion (Stutz & Gould 2016), as mentioned above and so we restrict our analysis here to this alignment mechanism.…”

Formation of massive seed black holes via collisions and accretion

“…III protostars, and to couple it to existing N -body codes and background potentials (e.g. Martínez-Barbosa et al 2016;Boekholt et al 2017). …”