The Burst Mode of Protostellar Accretion

By Eduard I. Vorobyov, S. Basu. 2006

270 citations recorded by the source corpus.

We present new numerical simulations in the thin disk approximation that characterize the burst mode of protostellar accretion. The burst mode begins upon the formation of a centrifugally balanced disk around a newly formed protostar. It comprises prolonged quiescent periods of low accretion rate (typically ≲10-7 M☉ yr-1) that are punctuated by intense bursts of accretion (typically ≳10-4 M☉ yr-1, with duration ≲100 yr) during which most of the protostellar mass is accumulated. The accretion bursts are associated with the formation of dense protostellar/protoplanetary embryos, which are later driven onto the protostar by the gravitational torques that develop in the disk. Gravitational instability in the disk, driven by continuing infall from the envelope, is shown to be an effective means of transporting angular momentum outward and mass inward to the protostar. We show that the disk mass always remains significantly less than the central protostar's mass throughout this process. The burst phenomenon is robust enough to occur for a variety of initial values of rotation rate and frozen-in (supercritical) magnetic field and a variety of density-temperature relations. Even in cases where the bursts are nearly entirely suppressed, a moderate increase in cloud size or rotation rate can lead to vigorous burst activity. We conclude that most (if not all) protostars undergo a burst mode of evolution during their early accretion history, as inferred empirically from observations of FU Orionis variables.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/d2b6549f8879e80f6a8a1949fbc95da5e4493473

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Citations in the corpus

Dynamics of Protoplanetary Disks (2010, background): “As the mass ratio between the disk and star increases, there is an increasing domination of low-order global spiral modes (illustrated in Figure 4), and a transition to timedependent “bursting” behavior (Vorobyov & Basu 2006).”
RADIATION MAGNETOHYDRODYNAMIC SIMULATIONS OF PROTOSTELLAR COLLAPSE: NONIDEAL MAGNETOHYDRODYNAMIC EFFECTS AND EARLY FORMATION OF CIRCUMSTELLAR DISKS (2015, background): “While mass and angular momentum transport by magnetic fields are almost steady and smooth, the gravitational torque via nonaxisymmetric structures is unsteady and episodic (see also Vorobyov & Basu 2006, 2010; Stamatellos et al. 2011).”
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).”
Identifying the Low-Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores (2007, background): “Theoretical studies have provided several mechanisms by which such a process may occur, such as material piling up in a circumstellar disk until gravitational instabilities drive angular momentum outward and mass inward in short-lived bursts (Vorobyov & Basu 2005, 2006).”
PROSAC: a submillimeter array survey of low-mass protostars - II. The mass evolution of envelopes, disks, and stars from the class 0 through I stages (2009, background): “…and from there onto the central starin highly episodic events: in their models for collapse of a dense core and formation of a protostar and disk, Vorobyov & Basu (2006) find strong episodic accretion once the disk has formed which keeps its mass lower than the stellar mass at all pointsduring…”
Theory of Star Formation (2007, background): “Vorobyov & Basu (2005b, 2006) propose, based on results of two-dimensional simulations, that recurrent “bursts” of accretion due to self-gravity are likely to develop during the early stages of protostellar evolution.”
Effect of Magnetic Braking on Circumstellar Disk Formation in a Strongly Magnetized Cloud (2010, methodology): “To mimic the thermal evolution calculated by Masunaga & Inutsuka (2000), we adopt the piece wise polytropic equation of state (see also Vorobyov & Basu 2006; Machida et al. 2007; Mellon & Li 2008, 2009; Inutsuka et al. 2010) as P = c2s,0 ρ [ 1 + ( ρ ρc )2/3 ] , (5) where cs,0 = 190m s −1 and ρc =…”
How do massive black holes get their gas (2009, background): “…Ruden & Shu 1989; Shu et al. 1990; Ostriker, Shu & Adams 1992; Bournaud et al. 2005), both in the galactic context and in protoplanetary or protostellar discs (e.g. Banerjee, Pudritz & Holmes 2004; Boley et al. 2006; Vorobyov & Basu 2006, 2009; Krumholz, Klein & McKee 2007; Cai et al. 2008).”
Gravitational Instabilities in Circumstellar Disks (2016, background): “Vorobyov & Basu (2006) suggest that www.annualreviews.org • GI DISKS 7 these same outbursts could be triggered by clumps formed due to gravitational instability in the outer disk that are tidally disrupted as they migrate inwards, and subsequently accrete onto the star.”
CHALLENGES IN FORMING PLANETS BY GRAVITATIONAL INSTABILITY: DISK IRRADIATION AND CLUMP MIGRATION, ACCRETION, AND TIDAL DESTRUCTION (2011, background): “However, early calculations (Vorobyov & Basu 2005, 2006) used a polytropic equation of state which can artificially enhance fragmentation (Boss 1997; Pickett et al. 2000; Gammie 2001).”
PROPERTIES OF THE YOUNGEST PROTOSTARS IN PERSEUS, SERPENS, AND OPHIUCHUS (2008, background): “In traditional models of episodic accretion, infall from the envelope onto the disk is constant and accretion from the disk onto the protostar is episodic (e.g., Kenyon & Hartmann 1995), for example due to gravitational instabilities in the disk (Vorobyov & Basu 2006).”
THE VLA NASCENT DISK AND MULTIPLICITY SURVEY OF PERSEUS PROTOSTARS (VANDAM). II. MULTIPLICITY OF PROTOSTARS IN THE PERSEUS MOLECULAR CLOUD (2016, background): “For instance, gravitationally unstable disk models often show clumps that have yet to collapse into stellar objects migrating inward (Vorobyov & Basu 2006, 2010).”
Rapid inward migration of planets formed by gravitational instability (2011, background): “…have observed that clumps could drift inwards (e.g., Mayer et al. 2002; Boss 2005; Cha & Nayakshin 2010), and some of them have focused on the early phases of disc formation and evolution following the collapse from the prestellar core stage (Vorobyov & Basu 2006, 2010a,b; Machida et al. 2011).”
VARIABLE PROTOSTELLAR ACCRETION WITH EPISODIC BURSTS (2015, methodology): “…are inward migration of fragments onto the protostar caused by the gravitational exchange of angular momentum with spiral arms and other fragments (Vorobyov & Basu 2006, 2010a; Machida et al. 2011; Tsukamoto et al. 2014), dispersal of fragments due to tidal torques (Boley et al. 2010; Zhu et al.…”
EVOLUTIONARY SIGNATURES IN THE FORMATION OF LOW-MASS PROTOSTARS. II. TOWARD RECONCILING MODELS AND OBSERVATIONS (2005, methodology): “Vorobyov & Basu (2005b) found 15 − 30 bursts in their initial simulation, but showed in Vorobyov & Basu (2006) that the exact number depends on assumed values of both Ω0 and the magnetic 15 Once the change in luminosity reaches the dust, it will respond very quickly to the change, reaching its new…”
Planet-Disk Interaction and Orbital Evolution (2012, background): “Vorobyov & Basu (2005, 2006) presented simulations of disk and protostar formation through cloud collapse, followed by disk fragmentation into a succession of protostellar/protoplanetary clumps that underwent rapid migration through the disk and the inner boundary of the computational domain…”
THE FORMATION MECHANISM OF GAS GIANTS ON WIDE ORBITS (2009, unknown): “…instabilities survive to become protoplanets or are destroyed by accretion onto the star or background shear flows (Durisen et al. 2007; Vorobyov & Basu 2006); furthermore, a previous investigation of planet formation on wide orbits by Boss (2006) noted that spiral instabilities may…”
FORMATION OF MASSIVE PRIMORDIAL STARS: INTERMITTENT UV FEEDBACK WITH EPISODIC MASS ACCRETION (2015, background): “The rapid inward migration of the fragments in gravitationally unstable disks is also commonly seen in simulations of present-day star and planet formation (e.g., Vorobyov & Basu 2006; Baruteau et al. 2011; Machida et al. 2011; Zhu et al. 2012).”
THREE-DIMENSIONAL SIMULATION OF MASSIVE STAR FORMATION IN THE DISK ACCRETION SCENARIO (2011, background): “…et al. 1992; Tomley et al. 1994; Laughlin & Bodenheimer 1994; Miyama et al. 1994; Papaloizou & Lin 1995a; Laughlin & Korchagin 1996; Laughlin & Rozyczka 1996; Bate 1998; Yorke & Bodenheimer 1999; Vorobyov & Basu 2006, 2007, 2010) in the accretion disk will transfer angular momentum to outer radii.”