Binary star formation: gravitational fragmentation followed by capture

Turner, J. A.; Chapman, Sydney; Bhattal, A. S.; Disney, M. J.; Pongracic, H.; Whitworth, Anthony Peter

doi:10.1093/mnras/277.2.705

Cited by 58 publications

(75 citation statements)

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“…We note that these levels of turbulence involve much lower non-thermal velocities than the earlier work of Whitworth et al (1995), Turner et al (1995), Whitworth et al (1996), Klein et al (2001Klein et al ( , 2003, Bate et al (2002aBate et al ( ,b, 2003, Bonnell et al (2003), Delgado-Donate (2003, 2004. Consequently they may be applicable to scenarios in which instability develops more quasistatically due to ambipolar diffusion; provided that some turbulence can persist through (or be regenerated after) the ambipolar diffusion phase, and provided the subsequent collapse is sufficiently rapid.…”

Section: Introductioncontrasting

confidence: 47%

“…In the highly dynamic scenario the collapse of a prestellar core is far more likely to lead to fragmentation and the formation of multiple systems (e.g., Whitworth et al 1995;Turner et al 1995;Whitworth et al 1996;Klein et al 2001Klein et al , 2003Bate et al 2002aBate et al ,b, 2003Bonnell et al 2003;Delgado-Donate 2003, 2004Goodwin et al 2004a,b;Hennebelle et al 2003Hennebelle et al , 2004. This is because in the highly dynamic scenario prestellar cores are formed non-quasistatically and therefore (a) they are launched directly into the non-linear regime of gravitational collapse, and (b) they are likely to have retained some internal turbulence.…”

Section: Introductionmentioning

confidence: 99%

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Simulating star formation in molecular cores

Goodwin¹,

Whitworth²,

Ward-Thompson³

2004

A&A

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127

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Abstract. We explore, by means of a large ensemble of SPH simulations, how the level of turbulence affects the collapse and fragmentation of a star-forming core. All our simulated cores have the same mass (5.4 M ), the same initial density profile (chosen to fit observations of L1544), and the same barotropic equation of state, but we vary (a) the initial level of turbulence (as measured by the ratio of turbulent to gravitational energy, α turb ≡ U turb /|Ω| = 0, 0.01, 0.025, 0.05, 0.10 and 0.25) and (b), for fixed α turb , the details of the initial turbulent velocity field (so as to obtain good statistics).

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Section: Introductioncontrasting

confidence: 47%

Section: Introductionmentioning

confidence: 99%

Simulating star formation in molecular cores

Goodwin¹,

Whitworth²,

Ward-Thompson³

2004

A&A

Self Cite

127

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“…carried out by Turner et al (1995) using the standard artificial viscosity of Monaghan (1989). In the implementation of the test (in both papers) the change in internal energy, du dt , was neglected.…”

Section: Discussionmentioning

confidence: 99%

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

Boffin¹,

Watkins²,

Bhattal³

et al. 1998

Monthly Notices RAS

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101

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It appears that most stars are born in clusters, and that at birth most stars have circumstellar discs which are comparable in size to the separations between the stars. Interactions between neighbouring stars and discs are therefore likely to play a key rôle in determining disc lifetimes, stellar masses, and the separations and eccentricities of binary orbits. Such interactions may also cause fragmentation of the discs, thereby triggering the formation of additional stars.We have carried out a series of simulations of disc-star interactions using an SPH code which treats self-gravity, hydrodynamic and viscous forces. We find that interactions between discs and stars provide a mechanism for removing energy from, or adding energy to, the orbits of the stars, and for truncating the discs. However, capture during such encounters is unlikely to be an important binary formation mechanism.A more significant consequence of such encounters is that they can trigger fragmentation of the disc, via tidally and compressionally induced gravitational instabilities, leading to the formation of additional stars. When the disc-spins and stellar orbits are randomly oriented, encounters lead to the formation of new companions to the original star in 20% of encounters. If most encounters are prograde and coplanar, as suggested by simulations of dynamically-triggered star formation, then new companions are formed in approximately 50% of encounters.

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“…As another example, an eccentricity distribution that is weighted toward large values implies a Maxwellian "thermal" orbital velocity distribution (Ambartsumian 1937;Kroupa 2008). Such a population would suggest that the binaries formed through dynamical interactions, possibly through tidal or disk capture, perturbations in a dense cluster, triple-star secular evolution/ Kozai cycles, and/or three-body exchanges (Heggie 1975;Pringle 1989;Kroupa 1995aKroupa , 1995bTurner et al 1995;Kiseleva et al 1998;Naoz & Fabrycky 2014). Meanwhile, circularized orbits demonstrate tidal evolution on the MS and/or pre-MS (Zahn 1977;Zahn & Bouchet 1989;Meibom & Mathieu 2005).…”

Section: Introductionmentioning

confidence: 99%

Mind Your Ps and Qs: The Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars

Moe

Stefano

2017

ApJS

1,060

1,200

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We compile observations of early-type binaries identified via spectroscopy, eclipses, long-baseline interferometry, adaptive optics, common proper motion, etc. Each observational technique is sensitive to companions across a narrow parameter space of orbital periods P and mass ratios q=M comp /M 1 . After combining the samples from the various surveys and correcting for their respective selection effects, we find that the properties of companions to O-type and B-type main-sequence (MS) stars differ among three regimes. First, at short orbital periods P20days (separations a0.4 au), the binaries have small eccentricities e0.4, favor modest mass ratios á ñ » q 0.5, and exhibit a small excess of twins q>0.95. Second, the companion frequency peaks at intermediate periods log P (days)≈3.5 (a ≈ 10 au), where the binaries have mass ratios weighted toward small values q≈0.2-0.3 and follow a Maxwellian "thermal" eccentricity distribution. Finally, companions with long orbital periods log P (days)≈5.5-7.5 (a ≈ 200-5000 au) are outer tertiary components in hierarchical triples and have a mass ratio distribution across q≈0.1-1.0 that is nearly consistent with random pairings drawn from the initial mass function. We discuss these companion distributions and properties in the context of binary-star formation and evolution. We also reanalyze the binary statistics of solar-type MS primaries, taking into account that 30% ±10% of single-lined spectroscopic binaries likely contain white dwarf companions instead of low-mass stellar secondaries. The mean frequency of stellar companions with q>0.1 and log P (days)<8.0 per primary increases from 0.50±0.04 for solar-type MS primaries to 2.1±0.3 for O-type MS primaries. We fit joint probability density functions ¹ ( ) ( ) ( ) ( ) ( ) f M q P e f M f q f P f e , , , 1 1 to the corrected distributions, which can be incorporated into binary population synthesis studies.

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Binary star formation: gravitational fragmentation followed by capture

Cited by 58 publications

References 0 publications

Simulating star formation in molecular cores

Simulating star formation in molecular cores

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

Mind Your Ps and Qs: The Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars

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