Circumventing the Radiation Pressure Barrier in the Formation of Massive Stars via Disk Accretion

Kuiper, Rolf; Klahr, Hubert; Beuther, H.; Henning, Thomas

doi:10.1088/0004-637x/722/2/1556

Cited by 253 publications

(324 citation statements)

References 68 publications

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“…Recent studies have demonstrated that this limitation holds only in spherical symmetry. As first envisioned by Nakano (1987) and recently demonstrated by Krumholz et al (2009) and Kuiper et al (2010), accretion through a circumstellar disk can explain the formation of stars up to the upper limit of the initial mass function, by allowing part of the photons to escape along the disk axis and boosting the ram pressure of the accreting gas through the small Based on observations carried out with the Submillimeter Array. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica.…”

Section: Introductionmentioning

confidence: 86%

Dissecting a hot molecular core: the case of G31.41+0.31

Cesaroni

Beltrán

Zhang

et al. 2011

A&A

118

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Context. The role of disks in the formation of high-mass stars is still a matter of debate but the detection of circumstellar disks around O-type stars would have a profound impact on high-mass star formation theories. Aims. We made a detailed observational analysis of a well known hot molecular core lying in the high-mass star-forming region G31.41+0.31. This core is believed to contain deeply embedded massive stars and presents a velocity gradient that has been interpreted either as rotation or as expansion, depending on the authors. Our aim was to shed light on this question and possibly prepare the ground for higher resolution ALMA observations, which could directly detect circumstellar disks around the embedded massive stars. Methods. Observations at sub-arcsecond resolution were performed with the Submillimeter Array in methyl cyanide, a typical hot molecular core tracer, and 12 CO and 13 CO, well known outflow tracers. We also obtained sensitive continuum maps at 1.3 mm. Results. Our findings confirm the existence of a sharp velocity gradient across the core, but cannot confirm the existence of a bipolar outflow perpendicular to it. The improved angular resolution and sampling of the uv plane allow us to attain higher quality channel maps of the CH 3 CN lines with respect to previous studies and thus significantly improve our knowledge of the structure and kinematics of the hot molecular core. Conclusions. While no conclusive argument can rule out any of the two interpretations (rotation or expansion) proposed to explain the velocity gradient observed in the core, in our opinion the observational evidence collected so far indicates the rotating toroid as the most likely scenario. The outflow hypothesis appears less plausible, because the dynamical time scale is too short compared to that needed to form species such as CH 3 CN, and the mass loss and momentum rates estimated from our measurements appear too high.

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Section: Introductionmentioning

confidence: 86%

Dissecting a hot molecular core: the case of G31.41+0.31

Cesaroni

Beltrán

Zhang

et al. 2011

A&A

118

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“…From the perspective of numerical development, the implementation and improvement of radiation transport schemes in (magneto-)hydrodynamics simulations is both a challenging and timely problem in modern astrophysics, especially in the field of (massive) star formation, in which the radiative feedback onto the environment plays a crucial role (Yorke & Sonnhalter 2002;Krumholz et al 2007Krumholz et al , 2009; Price & Bate 2009;Commercon et al 2010;Bate 2010;Kuiper et al 2010aKuiper et al , 2011.…”

Section: Introductionmentioning

confidence: 99%

“…Krumholz et al (2009) proposed that massive stars can grow beyond their Eddington limit because these radiation-pressuredominated cavity shells are subject to the so-called "radiative Rayleigh-Taylor instability" allowing additional mass to be fed onto the central accretion disk. Following the approach of Nakano (1989) and Yorke & Sonnhalter (2002), we proposed the feeding of a massive star beyond its Eddington limit by disk accretion only (Kuiper et al 2010a(Kuiper et al , 2011. While the anisotropy of the thermal radiation field sufficiently diminishes the radiation pressure onto the disk accretion flow near the midplane, the radiation pressure in the polar direction is able to launch an outflow, forming a stable cavity.…”

Section: Introductionmentioning

confidence: 99%

On the stability of radiation-pressure-dominated cavities

Kuiper¹,

Klahr²,

Beuther³

et al. 2012

A&A

139

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Context. When massive stars exert a radiation pressure onto their environment that is higher than their gravitational attraction (superEddington condition), they launch a radiation-pressure-driven outflow, which creates cleared cavities. These cavities should prevent any further accretion onto the star from the direction of the bubble, although it has been claimed that a radiative Rayleigh-Taylor instability should lead to the collapse of the outflow cavity and foster the growth of massive stars. Aims. We investigate the stability of idealized radiation-pressure-dominated cavities, focusing on its dependence on the radiation transport approach used in numerical simulations for the stellar radiation feedback. Methods. We compare two different methods for stellar radiation feedback: gray flux-limited diffusion (FLD) and ray-tracing (RT). Both methods are implemented in our self-gravity radiation hydrodynamics simulations for various initial density structures of the collapsing clouds, eventually forming massive stars. We also derive simple analytical models to support our findings.Results. Both methods lead to the launch of a radiation-pressure-dominated outflow cavity. However, only the FLD cases lead to prominent instability in the cavity shell. The RT cases do not show such instability; once the outflow has started, it precedes continuously. The FLD cases display extended epochs of marginal Eddington equilibrium in the cavity shell, making them prone to the radiative Rayleigh-Taylor instability. In the RT cases, the radiation pressure exceeds gravity by 1-2 orders of magnitude. The radiative Rayleigh-Taylor instability is then consequently suppressed. It is a fundamental property of the gray FLD method to neglect the stellar radiation temperature at the location of absorption and thus to underestimate the opacity at the location of the cavity shell. Conclusions. Treating the stellar irradiation in the gray FLD approximation underestimates the radiative forces acting on the cavity shell. This can lead artificially to situations that are affected by the radiative Rayleigh-Taylor instability. The proper treatment of direct stellar irradiation by massive stars is crucial for the stability of radiation-pressure-dominated cavities.

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“…Nakano 1989;Bernasconi & Maeder 1996;Yorke & Bodenheimer 2008;Kuiper et al 2010). While the general picture seems to be well defined, our knowledge of accretion history is far from being complete, and many questions regarding as to how the accretion history depends on the physics of the cloud (metallicity, turbulence) or of the already formed stars are still open.…”

Section: Introductionmentioning

confidence: 99%

“…The complex hydrodynamics of the accretion process itself is also a very active area of research (e.g. Peters et al 2010Peters et al , 2011Kuiper et al 2010Kuiper et al , 2011Girichidis et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Star formation with disc accretion and rotation

Haemmerlé¹,

Eggenberger

Meynet

et al. 2013

A&A

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Context. The way angular momentum is built up in stars during their formation process may have an impact on their further evolution. Aims. In the framework of the cold disc accretion scenario, we study how angular momentum builds up inside the star during its formation for the first time and what the consequences are for its evolution on the main sequence (MS). Methods. Computation begins from a hydrostatic core on the Hayashi line of 0.7 M at solar metallicity (Z = 0.014) rotating as a solid body. Accretion rates depending on the luminosity of the accreting object are considered, which vary between 1.5 × 10 −5 and 1.7 × 10 −3 M yr −1 . The accreted matter is assumed to have an angular velocity equal to that of the outer layer of the accreting star. Models are computed for a mass-range on the zero-age main sequence (ZAMS) between 2 and 22 M . Results. We study how the internal and surface velocities vary as a function of time during the accretion phase and the evolution towards the ZAMS. Stellar models, whose evolution has been followed along the pre-MS phase, are found to exhibit a shallow gradient of angular velocity on the ZAMS. Typically, the 6 M model has a core that rotates 50% faster than the surface on the ZAMS. The degree of differential rotation on the ZAMS decreases when the mass increases (for a fixed value of v ZAMS /v crit ). The MS evolution of our models with a pre-MS accreting phase show no significant differences with respect to those of corresponding models computed from the ZAMS with an initial solid-body rotation. Interestingly, there exists a maximum surface velocity that can be reached through the present scenario of formation for masses on the ZAMS larger than 8 M . Typically, only stars with surface velocities on the ZAMS lower than about 45% of the critical velocity can be formed for 14 M models. Reaching higher velocities would require starting from cores that rotate above the critical limit. We find that this upper velocity limit is smaller for higher masses. In contrast, there is no restriction below 8 M , and the whole domain of velocities to the critical point can be reached.

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Circumventing the Radiation Pressure Barrier in the Formation of Massive Stars via Disk Accretion

Cited by 253 publications

References 68 publications

Dissecting a hot molecular core: the case of G31.41+0.31

Dissecting a hot molecular core: the case of G31.41+0.31

On the stability of radiation-pressure-dominated cavities

Star formation with disc accretion and rotation

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