Numerical simulations of protostellar encounters - I. Star-disc encounters

Boffin, H. M. J.; Watkins, S. J.; Bhattal, A. S.; Francis, N.; Whitworth, A. P.

doi:10.1046/j.1365-8711.1998.01986.x

Cited by 76 publications

(111 citation statements)

References 32 publications

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“…Note that even the state-of-the-art star formation simulations of Bate (2012) -which form discs around protostars -have an SPH particle mass of 1.43 × 10 −5 M , implying that a 0.01M disc is composed of barely 700 resolution elements. Despite the rareness of events like direct star-disc and discdisc interactions, such encounters have received significant attention in the literature, either focusing on their role in the tidal evolution of a binary and orbital capture (Clarke & Pringle 1991a,b;Ostriker 1994), or by studying the possible triggering of spiral arms, gravitational instability (GI) and fragmentation (Boffin et al 1998;Lin et al 1998;Pfalzner 2003;Pfalzner, Umbreit & Henning 2005;Pfalzner & Olczak 2007;Forgan & Rice 2009;Shen et al 2010).…”

Section: Previous Workmentioning

confidence: 99%

“…Studies of disc-disc collisions by direct numerical simulation date back to Lin et al (1998) and Watkins et al (1998a,b) (see also Boffin et al 1998), where authors hypothesized that condensation of material in tidally induced tails could produce a population of brown dwarfs. This idea has been revisited both with pure N -body approaches (Pfalzner 2003;Pfalzner, Umbreit & Henning 2005;Thies, Kroupa & Theis 2005;Pfalzner & Olczak 2007) and with gas dynamics (Forgan & Rice 2009;Sheppard & Trujillo 2006;Shen et al 2010;Thies et al 2010).…”

Section: Previous Workmentioning

confidence: 99%

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Stellar orbit evolution in close circumstellar disc encounters

Muñoz

Kratter

Vogelsberger

et al. 2014

Monthly Notices of the Royal Astronomical Society

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The formation and early evolution of circumstellar discs often occurs within dense, newborn stellar clusters. For the first time, we apply the moving-mesh code AREPO, to circumstellar discs in 3-D, focusing on disc-disc interactions that result from stellar fly-bys. Although a small fraction of stars are expected to undergo close approaches, the outcomes of the most violent encounters might leave an imprint on the discs and host stars that will influence both their orbits and their ability to form planets. We first construct well-behaved 3-D models of self-gravitating discs, and then create a suite of numerical experiments of parabolic encounters, exploring the effects of pericenter separation r p , disc orientation and disc-star mass ratio (M d /M * ) on the orbital evolution of the host stars. Close encounters (2r p disc radius) can truncate discs on very short time scales. If discs are massive, close encounters facilitate enough orbital angular momentum extraction to induce stellar capture. We find that for realistic primordial disc masses M d 0.1M * , non-colliding encounters induce minor orbital changes, which is consistent with analytic calculations of encounters in the linear regime. The same disc masses produce entirely different results for grazing/colliding encounters. In the latter case, rapidly cooling discs lose orbital energy by radiating away the energy excess of the shock-heated gas, thus causing capture of the host stars into a bound orbit. In rare cases, a tight binary with a circumbinary disc forms as a result of this encounter.

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Section: Previous Workmentioning

confidence: 99%

Section: Previous Workmentioning

confidence: 99%

Stellar orbit evolution in close circumstellar disc encounters

Muñoz

Kratter

Vogelsberger

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…SPH is now used widely to simulate the evolution of disks (Bate et al 2003;Rice et al 2003aRice et al ,b, 2004Mayer et al 2004;Schaefer et al 2004;Boffin et al 1998;Watkins et al 1998a,b;Stamatellos et al 2008Stamatellos et al , 2009). The behaviour of viscosity in real circular shear flow in fluids is understood analytically and experimentally (e.g.…”

Section: Introductionmentioning

confidence: 99%

Controlling artificial viscosity in smoothed particle hydrodynamics simulations of accretion disks

Cartwright

Stamatellos

2010

A&A

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Context. The fidelity of smoothed particle hydrodynamics (SPH) simulations of accretion disks depends on how artificial viscosity (AV) is formulated. Aims. We investigate whether standard methodology is reliable in this regard. Methods. We test the operation of two methods for selective application of AV in SPH simulations of Keplerian accretion disks, using a ring spreading test to quantify effective viscosity, and a correlation coefficient technique to measure the formation of unwanted prograde alignments of particles. Results. Neither the Balsara switch (B) nor time dependent viscosity (TDV) work effectively, as they leave AV active in areas of smooth shearing flow, and do not eliminate the accumulation of alignments of particles in the prograde direction. The effect of both switches is periodic, the periodicity dependent on radius and unaffected by the density of particles. We demonstrate that a very simple algorithm activates AV only when truly convergent flow is detected and reduces the unwanted formation of prograde alignments. The new switch works by testing whether all the neighbours of a particle are in Keplerian orbit around the same point, rather than calculating the divergence of the velocity field, which is very strongly affected by Poisson noise in the positions of the SPH particles.

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“…In contrast to previous investigations (Clarke & Pringle 1993;Hall et al 1996;Boffin et al 1998;Pfalzner 2004;Pfalzner et al 2005a;Olczak et al 2006;Moeckel & Bally 2006;Kley et al 2008) we concentrate on the influence of the mass distributions in the disc on the resulting disc frequency.…”

Section: Introductionmentioning

confidence: 99%

“…Among the great variety of effects are internal processes such as viscous torques (e.g. Shu et al 1987), turbulent effects (Klahr & Bodenheimer 2003), and magnetic fields (Balbus & Hawley 2002), but also external disc destruction processes like photoevaporation (Scally & Clarke 2001;Clarke et al 2001;Matsuyama et al 2003;Johnstone et al 2004;Alexander et al 2005Alexander et al , 2006Ercolano et al 2008;Drake et al 2009;Gorti & Hollenbach 2009) and tidal interactions (Heller 1993;Hall et al 1996;Clarke & Pringle 1993;Ostriker 1994;Heller 1995;Hall 1997;Larwood 1997;Boffin et al 1998;Pfalzner 2004;Pfalzner et al 2005a;Moeckel & Bally 2006;Kley et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Does the mass distribution in discs influence encounter-induced losses in young star clusters?

Steinhausen

Pfalzner

2014

A&A

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Context. One mechanism for the external destruction of protoplanetary discs in young dense clusters is tidal disruption during the flyby of another cluster member. The degree of mass loss in such an encounter depends, among other parameters, on the distribution of the material within the disc. Previous work showed that this is especially so in encounters that truncate large parts of the outer disc. The expectation is that the number of completely destroyed discs in a cluster also depends on the mass distribution within the discs. Aims. Here we test this hypothesis by determining the influence of encounters on the disc fraction and average disc mass in clusters of various stellar densities for different mass distributions in the discs.Methods. This is done by performing 6 simulations of a variety of cluster environments, where we track the encounter dynamics and determine the mass loss due to these encounters for different disc-mass distributions. Results. We find that although the disc-mass distribution has a significant impact on the disc losses for specific star-disc encounters, the overall disc frequency generally remains unaffected. The reason is that in single encounters the dependence on the mass distribution is strongest if both stars have very different masses. Such encounters are rather infrequent in sparse clusters. In dense clusters these encounters are more common; however, here the disc frequency is largely determined by encounters between low-mass stars such that the overall disc frequency does not change significantly. Conclusions. For tidal disruption the disc destruction in clusters is fairly independent of the actual distribution of the material in the disc. The all determining factor remains the cluster density.

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Numerical simulations of protostellar encounters - I. Star-disc encounters

Cited by 76 publications

References 32 publications

Stellar orbit evolution in close circumstellar disc encounters

Stellar orbit evolution in close circumstellar disc encounters

Controlling artificial viscosity in smoothed particle hydrodynamics simulations of accretion disks

Does the mass distribution in discs influence encounter-induced losses in young star clusters?

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