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

Abstract

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 w 10 3 km/s) winds. These winds will collide with the surrounding gas producing shock-heated (T ∼ 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.

Effects of the environment and feedback physics on the initial mass function of stars in the STARFORGE simulations

“…Radiation from accreting protostars is thought to be a crucial ingredient of the star formation process for both low and high-mass stars (Offner et al 2009;Krumholz et al 2011;Krumholz 2011;Bate 2012;Myers et al 2013;Guszejnov & Hopkins 2016;Guszejnov et al 2016;Rosen et al 2016;Cunningham et al 2018; as they can heat their surroundings, preventing fragmentation. Once stars reach the main sequence they start emitting ionizing radiation as well as isotropic line-driven stellar winds, both of which can dramatically affect their surroundings, potentially halting stellar accretion (Krumholz et al 2012;Rosen et al 2016;Li et al 2018;Cunningham et al 2018;Rosen 2022). Massive stars in particular provide feedback powerful enough to affect the IMF in their entire natal cloud (Gavagnin et al 2017), as well as completely quench star formation (see Krumholz et al 2019 for review and Fig.…”

Effects of the environment and feedback physics on the initial mass function of stars in the STARFORGE simulations

“…Radiation from accreting protostars is thought to be a crucial ingredient of the star formation process for both low and high-mass stars (Offner et al 2009;Krumholz et al 2011;Krumholz 2011;Bate 2012;Myers et al 2013;Guszejnov & Hopkins 2016;Guszejnov et al 2016;Rosen et al 2016;Cunningham et al 2018; as they can heat their surroundings, preventing fragmentation. Once stars reach the main sequence they start emitting ionizing radiation as well as isotropic line-driven stellar winds, which can dramatically affect their surroundings, potentially halting stellar accretion (Krumholz et al 2012;Rosen et al 2016;Li et al 2018;Cunningham et al 2018;Rosen 2022). Massive stars in particular provide feedback powerful enough to affect the IMF in their entire natal cloud (Gavagnin et al 2017), as well as completely quench star formation (see Krumholz et al 2019 for review and Fig.…”