H II REGIONS: WITNESSES TO MASSIVE STAR FORMATION

By Thomas Peters, Robi Banerjee, Ralf Klessen, M. Mac Low, R. Galván-Madrid, E. Keto. 2010

199 citations recorded by the source corpus.

We describe the first three-dimensional simulation of the gravitational collapse of a massive, rotating molecular cloud that includes heating by both non-ionizing and ionizing radiation. These models were performed with the FLASH code, incorporating a hybrid, long characteristic, ray-tracing technique. We find that as the first protostars gain sufficient mass to ionize the accretion flow, their H II regions are initially gravitationally trapped, but soon begin to rapidly fluctuate between trapped and extended states, in agreement with observations. Over time, the same ultracompact H II region can expand anisotropically, contract again, and take on any of the observed morphological classes. In their extended phases, expanding H II regions drive bipolar neutral outflows characteristic of high-mass star formation. The total lifetime of H II regions is given by the global accretion timescale, rather than their short internal sound-crossing time. This explains the observed number statistics. The pressure of the hot, ionized gas does not terminate accretion. Instead, the final stellar mass is set by fragmentation-induced starvation. Local gravitational instabilities in the accretion flow lead to the build-up of a small cluster of stars, all with relatively high masses due to heating from accretion radiation. These companions subsequently compete with the initial high-mass star for the same common gas reservoir and limit its mass growth. This is in contrast to the classical competitive accretion model, where the massive stars are never hindered in growth by the low-mass stars in the cluster. Our findings show that the most significant differences between the formation of low-mass and high-mass stars are all explained as the result of rapid accretion within a dense, gravitationally unstable, ionized flow.

Subfields: Astronomy and Astrophysics, Instrumentation, Physical and Theoretical Chemistry

View Paper: https://www.semanticscholar.org/paper/db98926236ef0cbee73dd84595bedec2552f2432

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Citations in the corpus

RADIATION-HYDRODYNAMIC SIMULATIONS OF THE FORMATION OF ORION-LIKE STAR CLUSTERS. II. THE INITIAL MASS FUNCTION FROM WINDS, TURBULENCE, AND RADIATION (2012, background): “Peters et al. (2010) do form massive stars, but from a cloud with a mean density of 103 cm−3 and a column density of 0.026 g cm−2, far below the column density at which radiative effects become important (Krumholz & McKee 2008; Krumholz et al. 2010) – so low, in fact, as to be optically thin in the…”
The First Stars: Mass Growth Under Protostellar Feedback (2011, background): “Indeed, the final estimated mass of the main sink is similar to that found in Peters et al. (2010a), where they found the combination of disk fragmentation and radiative feedback led to a most-massive star of 25 M⊙.”
The SILCC (SImulating the LifeCycle of molecular Clouds) project - II. Dynamical evolution of the supernova-driven ISM and the launching of outflows (2015, unknown): “Numerical studies support this paradigm and show efficient heating of the surroundings by OB stars (Dale et al. 2005; Peters et al. 2010; Arthur et al. 2011; Walch et al. 2012; Dale et al. 2014; Geen et al. 2015).”
Modeling UV Radiation Feedback from Massive Stars. II. Dispersal of Star-forming Giant Molecular Clouds by Photoionization and Radiation Pressure (2018, background): “As a result, the size and shape of the H II region and photoevaporation rate fluctuate with time until they completely exhaust accretion flows and break out to larger radii at late time (e.g., Peters et al. 2010; Dale et al. 2012).”
THE GENERATION OF STRONG MAGNETIC FIELDS DURING THE FORMATION OF THE FIRST STARS (2010, background): “The effects of radiation have been shown in contemporary star formation (Krumholz et al. 2005, 2007; Peters et al. 2010a,b), and are likely to be important for the first stars as well (Wise & Abel 2008; Greif et al. 2009).”
THREE-DIMENSIONAL SIMULATION OF MASSIVE STAR FORMATION IN THE DISK ACCRETION SCENARIO (2011, background): “Fragmentation on larger scales potentially limits the mass reservoir of the forming star in the center (Krumholz et al. 2009; Peters et al. 2010b,c), although Peters et al. (2010a) recently have shown that a large scale magnetic field will offer locally support against gravitational collapse…”
Importance of the Initial Conditions for Star Formation - I. Cloud Evolution and Morphology (2010, background): “Hence, the accretion on to the central object is starved by the fragmentation around it (Peters et al. 2010a)”
THE STAR FORMATION RATE OF TURBULENT MAGNETIZED CLOUDS: COMPARING THEORY, SIMULATIONS, AND OBSERVATIONS (2012, background): “…Tamburro et al. 2009) or growing Hii regions around massive stars and clusters of stars (McKee 1989; Krumholz et al. 2006; Gritschneder et al. 2009; Peters et al. 2010; Goldbaum et al. 2011) as well as compression of ISM gas in galactic spiral shocks (Elmegreen 2009) and gravitational contraction…”
Dynamic star formation in the massive DR21 filament (2010, background): “However, theoretical work (Yorke & Sonnhalter 2002; Krumholz, McKee, Klein 2005; Peters et al. 2010) has shown that outflows lead to anisotropy in the stellar radiation field, which reduce the radiation effects experienced by gas in the infalling envelope.”
The SILCC project - III. Regulation of star formation and outflows by stellar winds and supernovae (2016, background): “Eventually, newly formed massive stars (with mass >8 M⊙) strongly impact the surrounding ISM by ionizing radiation (e.g. Peters et al. 2010, 2011; ⋆ E-mail: walch@ph1.uni-koeln.de (SW); naab@mpa-garching.mpg.de (TN) Dale, Ercolano & Bonnell 2012; Walch et al. 2012, 2013; Dale et al. 2014; Geen et…”
SIMULATIONS ON A MOVING MESH: THE CLUSTERED FORMATION OF POPULATION III PROTOSTARS (2011, methodology): “Radiation Feedback Studies of present-day star formation have shown that the radiation emitted by young protostars heats the surrounding envelope and reduces the degree of fragmentation near the central protostar (Krumholz et al. 2009; Peters et al. 2010).”
Collapse, outflows and fragmentation of massive, turbulent and magnetized prestellar barotropic cores (2011, methodology): “We note that recently Commerçon et al. (2010), Tomida et al. (2010) and Peters et al. (2010d) have performed the first simulations of collapsing low mass cores at small scales with grid techniques, which simultaneously consider the magnetic field and the radiative transfer, while Price & Bate…”
Physical Processes in the Interstellar Medium (2014, background): “The same holds when taking the effects of ionizing radiation into account (Peters et al., 2010a; Peters et al., 2010b, 2011; Commerçon et al., 2011).”
The energy and momentum input of supernova explosions in structured and ionized molecular clouds (2014, background): “In addition to winds, ionizing radiation heats the ambient medium and shapes the density structure of the molecular cloud (MC), thereby creating high density pillars and low density cavities (e.g. Dale et al. 2009; Gritschneder et al. 2010; Peters et al. 2010; Walch et al. 2012).”
THE INTERPLAY OF MAGNETIC FIELDS, FRAGMENTATION, AND IONIZATION FEEDBACK IN HIGH-MASS STAR FORMATION (2010, methodology): “In addition to the effect of radiation feedback, which raises the Jeans mass locally and reduces fragmentation (see Peters et al. 2010b for a thorough discussion), fragmentation is further reduced in this simulation by the magnetic field, just as is found in models of low-mass star formation (see…”
LIMITING ACCRETION ONTO MASSIVE STARS BY FRAGMENTATION-INDUCED STARVATION (2010, methodology): “In the current study, we analyze the simulations by Peters et al. (2010a) with special focus on the mass growth history of the individual stars forming and the physical processes that influence their accretion rate.”
ATLASGAL — towards a complete sample of massive star forming clumps ⋆ (2014, background): “The association of these compact radio sources with methanol masers may indicate that accretion continues after the formation of the H II regions through ionized infall (Keto 2003, 2007) or through the partial shielding of the ionizing radiation by the accretion flow (Peters et al. 2010).”
COLLAPSE OF MASSIVE MAGNETIZED DENSE CORES USING RADIATION MAGNETOHYDRODYNAMICS: EARLY FRAGMENTATION INHIBITION (2011, background): “…al. 2001; Bonnell & Bate 2006) and radiative calculations (Krumholz et al. 2007, 2009), magnetized ones (Wang et al. 2010; Hennebelle et al. 2011; Peters et al. 2011; Seifried et al. 2011) and even calculations including radiative ionization (Peters et al. 2010), all tend to form several fragments.”