NONSTEADY ACCRETION IN PROTOSTARS

By Zhaohuan Zhu, L. Hartmann, Charles F. Gammie. 2008

176 citations recorded by the source corpus.

Observations indicate that mass accretion rates onto low-mass protostars are generally lower than the rates of infall to their disks; this suggests that much of the protostellar mass must be accreted during rare, short outbursts of rapid accretion. We explore when protostellar disk accretion is likely to be highly variable. While constant α disks can in principle adjust their accretion rates to match infall rates, protostellar disks are unlikely to have constant α. In particular, we show that neither models with angular momentum transport due solely to the magnetorotational instability (MRI) nor gravitational instability (GI) are likely to transport disk mass at protostellar infall rates over the large range of radii needed to move infalling envelope material down to the central protostar. We show that the MRI and GI are likely to combine to produce outbursts of rapid accretion starting at a few AU. Our analysis is consistent with the time-dependent models of Armitage et al. and agrees with our observational study of the outbursting object FU Ori.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/82fa682510f5655f0d2e24e70d51673aed407fae

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In Astronomy and Astrophysics

1. L. Hartmann
2. R. Nelson
3. G. Herczeg
4. N. Calvet
5. Eduard I. Vorobyov
6. Zhaohuan Zhu
7. S. Basu
8. S. Paardekooper

In Spectroscopy

1. Eduard I. Vorobyov
2. L. Hartmann
3. G. Herczeg
4. N. Calvet
5. S. Basu
6. Zhaohuan Zhu
7. R. Nelson
8. S. Paardekooper

Citations in the corpus

• Accretion onto Pre-Main-Sequence Stars (2016, methodology): “Evolutionary tracks of protostars under different assumptions, compared with the Hertzsprung–Russell diagram positions of young stars in the Orion Nebula Cluster (Da Rio et al. 2014) ( gray dots) and Taurus protostars (Doppmann et al. 2005) (magenta dots with error bars).”
• Rapid inward migration of planets formed by gravitational instability (2011, background): “…to be too hot to be gravitationally unstable, and other sources of turbulence such as the magnetorotational instability could prevail (see e.g., Zhu et al. 2009; Rice & Armitage 2009; Clarke 2009, who studied the radial dependence of the alpha viscosity parameter in self-gravitating discs with…”
• THE BURST MODE OF ACCRETION AND DISK FRAGMENTATION IN THE EARLY EMBEDDED STAGES OF STAR FORMATION (2010, background): “Bell & Lin 1994; Armitage et al. 2001; Lodato & Clarke 2004; Vorobyov & Basu 2005, 2006; Pfalzner et al. 2008; Zhu et al. 2009, 2010; Forgan & Rice 2010; Bate 2010).”
• CHALLENGES IN FORMING PLANETS BY GRAVITATIONAL INSTABILITY: DISK IRRADIATION AND CLUMP MIGRATION, ACCRETION, AND TIDAL DESTRUCTION (2011, methodology): “Thus, we have updated our low density opacity in Zhu et al. (2009), including water ice, carbonate and silicate grains.”
• VARIABLE PROTOSTELLAR ACCRETION WITH EPISODIC BURSTS (2015, background): “A combination of the magneto-rotational and thermal instabilities in the inner several AU and gravitational instability further out in the disk (or layered accretion) was shown to produce accretion bursts typical for FU-Orionis-type eruptions (Armitage et al. 2001; Zhu et al. 2009).”