A Massive Star is Born: How Feedback from Stellar Winds, Radiation Pressure, and Collimated Outflows Limits Accretion onto Massive Stars

Anna L. Rosen

Published 2022-04-20Version 1

Massive protostars attain high luminosities as they are actively accreting and the radiation pressure exerted on the gas in the star's atmosphere may launch isotropic high-velocity ($v_{\rm w} \gtrsim 10^3$ km/s) winds. These winds will collide with the surrounding gas producing shock-heated ($T\sim 10^7$ K) tenuous gas that adiabatically expands and pushes on the dense gas that may otherwise be accreted. We present a series of 3D radiation-magnetohydrodynamic simulations of the collapse of massive prestellar cores and include radiative feedback from the direct stellar and dust-reprocessed radiation fields, collimated outflows, and, for the first time, isotropic stellar winds to model how these processes affect the formation of massive (proto)stars. We find that winds are initially launched when the massive protostar is still accreting and the wind properties evolve as the star contracts to the main sequence. Wind feedback drives asymmetric adiabatic wind bubbles that have a bipolar morphology because the dense circumstellar material pinches the expansion of the hot shock-heated gas, which preferentially expands along low-density channels. We term this the "wind tunnel effect." For unmagnetized cores, we find that wind feedback eventually quenches accretion onto massive stars. For magnetized cores, we find that wind feedback is less efficient at halting the accretion flow initially because magnetic tension delays the growth of the wind-driven bubbles. Once winds become strong enough, wind feedback launches adiabatic wind bubbles that eventually reduce accretion. Additionally, we discuss the implications of observing adiabatic wind bubbles with Chandra while the massive protostars are still highly embedded.