VARIABLE PROTOSTELLAR ACCRETION WITH EPISODIC BURSTS

By Eduard I. Vorobyov, S. Basu. 2015

142 citations recorded by the source corpus.

We present the latest development of the disk gravitational instability and fragmentation model, originally introduced by us to explain episodic accretion bursts in the early stages of star formation. Using our numerical hydrodynamics model with improved disk thermal balance and star-disk interaction, we computed the evolution of protostellar disks formed from the gravitational collapse of prestellar cores. In agreement with our previous studies, we find that cores of higher initial mass and angular momentum produce disks that are more favorable to gravitational instability and fragmentation, while a higher background irradiation and magnetic fields moderate the disk tendency to fragment. The protostellar accretion in our models is time-variable, thanks to the nonlinear interaction between different spiral modes in the gravitationally unstable disk, and can undergo episodic bursts when fragments migrate onto the star owing to the gravitational interaction with other fragments or spiral arms. Most bursts occur in the partly embedded Class I phase, with a smaller fraction taking place in the deeply embedded Class 0 phase and a few possible bursts in the optically visible Class II phase. The average burst duration and mean luminosity are found to be in good agreement with those inferred from observations of FUors. The model predicts the existence of two types of bursts: the isolated ones, showing well-defined luminosity peaks separated with prolonged periods ( ∼ 10 4 ?> yr) of quiescent accretion, and clustered ones, demonstrating several bursts occurring one after another during just a few hundred years. Finally, we estimate that 40%–70% of the star-forming cores can display bursts after forming a star-disk system.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/a45a81d897e89291a03701c0e3a3af511a72f075

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In Astronomy and Astrophysics

1. Naoki Yoshida
2. T. Hosokawa
3. G. Herczeg
4. H. Yorke
5. S. Hirano
6. K. Omukai
7. N. Calvet
8. R. Kuiper

In Atomic and Molecular Physics, and Optics

1. Naoki Yoshida
2. H. Yorke
3. T. Hosokawa
4. S. Hirano
5. N. R. Center
6. L. Hartmann
7. C. Walmsley
8. A. Ferrara

In Instrumentation

1. G. Herczeg
2. L. Hartmann
3. N. Calvet
4. T. Hosokawa
5. K. Omukai
6. Naoki Yoshida
7. S. Hirano
8. R. Kuiper

Citations in the corpus

• Accretion onto Pre-Main-Sequence Stars (2016, background): “…could be explained by highly time-variable accretion, where much of the mass was accreted in short bursts like those of FU Ori objects (Section 2.5), so that most protostars are observed in a low-accretion, low-luminosity state (see also Vorobyov & Basu 2005, 2010, 2015, Bae et al. 2013, 2014).”
• Disk-mediated accretion burst in a high-mass young stellar object (2016, background): “sibly caused by disk fragmentation (2; 3; 4).”
• FORMATION OF MASSIVE PRIMORDIAL STARS: INTERMITTENT UV FEEDBACK WITH EPISODIC MASS ACCRETION (2015, methodology): “However, Vorobyov & Basu (2015) also point out that the ejection events are much rarer than the burst accretion events initiated by the migration of fragments.”