SPH simulations of tidally unstable accretion discs in cataclysmic variables

Murray, J. R.

doi:10.1093/mnras/279.2.402

Cited by 144 publications

(232 citation statements)

References 15 publications

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“…The SPH equations and approximations have been rigorously established by Bicknell (1991). Our code was based on that of Murray (1996), originally developed to study tidally unstable accretion disks in cataclysmic variables. We have made several major changes: the configuration is for that of a protoplanetary disk rather than a binary disk and we have modified the algorithm for finding near neighbours so that the code can better handle variable spatial resolution.…”

Section: Description Of the Codementioning

confidence: 99%

“…In the results presented in this paper, we did not calculate the drag force of dust on gas because it is negligible in magnitude and computationally time consuming, but it is implemented into the code and can be turned on if required. We do not review the SPH method as it has been extensively described (see, for example, Monaghan 1992), but stress the changes made to the code written by Murray (1996) in the following subsections.…”

Section: Description Of the Codementioning

confidence: 99%

“…As our code does not include self gravity, rather that using a tree code to find neighbours (see Hernquist & Katz 1989), we use a less time consuming link list. In the original implementation of the code, the cells in the linked list were 2h max in size, where h max was the maximum value of the smoothing length over the entire simulation (Murray 1996). With such a cell size, a given particle's neighbours laid either in the same link cell or in one immediately neighbouring it.…”

Section: Smoothing Length and Link Listmentioning

confidence: 99%

“…where Π ab is the SPH artificial viscosity as described in Murray (1996). The volume scaling is ensured by the multiplication by the void fraction θ.…”

Section: Drag Forcementioning

confidence: 99%

“…This allows us to enter the gravity routine several times while only entering the pressure routine once. The pressure defines the global timestep δt, such that δt = 0.4δt p , while δt g gives the number of times the gravity routine is run after a single run of the pressure routine, following Murray (1996).…”

Section: Timestepmentioning

confidence: 99%

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Dust distribution in protoplanetary disks

Barrière-Fouchet

Gonzalez

Murray

et al. 2005

A&A

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We present the results of a three dimensional, locally isothermal, non-self-gravitating SPH code which models protoplanetary disks with two fluids: gas and dust. We ran simulations of a 1 M star surrounded by a 0.01 M disk comprising 99% gas and 1% dust in mass and extending from 0.5 to ∼300 AU. The grain size ranges from 10 −6 m to 10 m for the low resolution (∼25 000 SPH particles) simulations and from 10 −4 m to 10 cm for the high resolution (∼160 000 SPH particles) simulations. Dust grains are slowed down by the sub-Keplerian gas and lose angular momentum, forcing them to migrate towards the central star and settle to the midplane. The gas drag efficiency varies according to the grain size, with the larger bodies being weakly influenced and following marginally perturbed Keplerian orbits, while smaller grains are strongly coupled to the gas. For intermediate sized grains, the drag force decouples the dust and gas, allowing the dust to preferentially migrate radially and efficiently settle to the midplane. The resulting dust distributions for each grain size will indicate, when grain growth is added, the regions when planets are likely to form.

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Section: Description Of the Codementioning

confidence: 99%

Section: Description Of the Codementioning

confidence: 99%

Section: Smoothing Length and Link Listmentioning

confidence: 99%

“…where Π ab is the SPH artificial viscosity as described in Murray (1996). The volume scaling is ensured by the multiplication by the void fraction θ.…”

Section: Drag Forcementioning

confidence: 99%

Section: Timestepmentioning

confidence: 99%

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Dust distribution in protoplanetary disks

Barrière-Fouchet

Gonzalez

Murray

et al. 2005

A&A

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Effects of local thermodynamics and of stellar mass ratio on accretion disc stability in close binaries

Lanzafame¹

2009

Astron Nachr

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Inflow kinematics at the inner Lagrangian point L1, gas compressibility, and physical turbulent viscosity play a fundamental role on accretion disc dynamics and structure in a close binary (CB). Physical viscosity supports the accretion disc development inside the primary gravitational potential well, developing the gas radial transport, converting mechanical energy into heat. The Stellar-Mass-Ratio (SMR) between the compact primary and the secondary star (M1/M2) is also effective, not only in the location of the inner Lagrangian point, but also in the angular kinematics of the mass transfer and in the geometry of the gravitational potential wells. In this work we pay attention in particular to the role of the SMR, evaluating boundaries, separating theoretical domains in compressibility-viscosity graphs where physical conditions allow a well-bound disc development, as a function of mass transfer kinematic conditions. In such domains, the lower is the gas compressibility (the higher the polytropic index γ), the higher is the physical viscosity (α) requested. In this work, we show how the boundaries of such domains vary as a function of M1/M2. Conclusions as far as dwarf novae outbursts are concerned, induced by mass transfer rate variations, are also reported. The smaller M1/M2, the shorter the duration of the active-to-quiet and vice-versa transitional phases. Time-scales are of the order of outburst duration of SU Uma, OY Car, Z Cha and SS Cyg-like objects. Moreover, conclusions as far as active-quiet-active phenomena in a CB, according to viscous-thermal instabilities, in accordance to such domains, are also reported.

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