Formation of massive stars by growing accretion rate

Behrend, R.; Maeder, A.

doi:10.1051/0004-6361:20010585

Cited by 165 publications

(216 citation statements)

References 15 publications

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“…1) There are still many uncertainties on the accretion rates, and we think that the present choice remains an interesting possibility, since the birthline resulting from this law fits well with the observed upper envelope in the HR diagram of the positions of Herbig Ae/Be objects (see Fig. 1 in Behrend & Maeder 2001).…”

Section: Mass Accretion Ratesupporting

confidence: 68%

“…We use the same accretion law as in Behrend & Maeder (2001). Let us recall a few points about this accretion law.…”

Section: Mass Accretion Ratementioning

confidence: 99%

“…To deduce an accretion rate fromṀ out , Behrend & Maeder (2001) made the hypothesis that a constant fraction f of the mass collapsing from the accretion reservoir is accreted by the star. The other fraction, (1 − f ), produces the outflow of Eq.…”

Section: Mass Accretion Ratementioning

confidence: 99%

“…In the following we adopt a value of 1/3 for f , as in Behrend & Maeder (2001). This implies that the accretion rate is equal to half of the mass outflow.…”

Section: Mass Accretion Ratementioning

confidence: 99%

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Star formation with disc accretion and rotation

Haemmerlé¹,

Eggenberger²,

Meynet³

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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Section: Mass Accretion Ratesupporting

confidence: 68%

“…We use the same accretion law as in Behrend & Maeder (2001). Let us recall a few points about this accretion law.…”

Section: Mass Accretion Ratementioning

confidence: 99%

Section: Mass Accretion Ratementioning

confidence: 99%

“…In the following we adopt a value of 1/3 for f , as in Behrend & Maeder (2001). This implies that the accretion rate is equal to half of the mass outflow.…”

Section: Mass Accretion Ratementioning

confidence: 99%

See 2 more Smart Citations

Star formation with disc accretion and rotation

Haemmerlé¹,

Eggenberger²,

Meynet³

et al. 2013

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the context of simple models with spherical geometry, the possibility of accretion through the thermal pressure of H ii regions was discussed in Walmsley (1995) and Keto (2002a, 2002b, hereafter K02a andK02b, respectively), and the possibilities of accretion through radiation pressure were discussed in Kahn (1974), Yorke (1984Yorke ( , 2001, and Wolfire & Cassinelli (1987). The effects of massive accretion flows onto the protostars themselves have been studied in a series of papers by Beech & Mitalas (1994), Bernasconi & Maeder (1996), Meynet & Maeder (2000), Norberg & Maeder (2000), and Behrend & Maeder (2001). In this paper, the relationships between these hypotheses are explored in the search for a consistent model for massive star formation.…”

Section: Introductionmentioning

confidence: 99%

The Formation of Massive Stars by Accretion through Trapped Hypercompact HiiRegions

Keto¹

2003

ApJ

197

189

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The formation of massive stars may take place at relatively low accretion rates over a long period of time if the accretion can continue past the onset of core hydrogen ignition. The accretion may continue despite the formation of an ionized H ii region around the star if the H ii region is small enough that the gravitational attraction of the star dominates the thermal pressure of the H ii region. The accretion may continue despite radiation pressure acting against dust grains in the molecular gas if the momentum of the accretion flow is sufficient to push the dust grains through a narrow zone of high dust opacity at the ionization boundary and into the H ii region where the dust is sublimated. This model of massive star formation by continuing accretion predicts a new class of gravitationally trapped, long-lived, hypercompact H ii regions. The observational characteristics of the trapped hypercompact H ii regions can be predicted for comparison with observations.

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T Tauri star magnetic fields and magnetospheres

Hussain¹

2012

Astron Nachr

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Stellar magnetic fields govern key aspects of the evolution of a young star, from controlling accretion to regulating the angular momentum evolution of the system. Spectro-polarimetric studies of T Tauri stars have revealed a surprising range of magnetic field topologies. Meanwhile multi-wavelength campaigns have probed T Tauri star systems from stellar photosphere to inner disk, allowing us to study magnetospheric accretion in unprecedented detail. We review recent results and discuss their implications for understanding the evolution of young stars.

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Formation of massive stars by growing accretion rate

Cited by 165 publications

References 15 publications

Star formation with disc accretion and rotation

Star formation with disc accretion and rotation

The Formation of Massive Stars by Accretion through Trapped Hypercompact HiiRegions

T Tauri star magnetic fields and magnetospheres

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