# A numerical method for generating rapidly rotating bipolytropic structures in equilibrium

@article{Kadam2016ANM, title={A numerical method for generating rapidly rotating bipolytropic structures in equilibrium}, author={Kundan Kadam and Patrick M. Motl and Juhan Frank and Geoffrey C. Clayton and Dominic Marcello}, journal={Monthly Notices of the Royal Astronomical Society}, year={2016}, volume={462}, pages={2237-2245} }

We demonstrate that rapidly rotating bipolytropic (composite polytropic) stars and toroidal disks can be obtained using Hachisu's self consistent field technique. The core and the envelope in such a structure can have different polytropic indices and also different average molecular weights. The models converge for high $T/|W|$ cases, where T is the kinetic energy and W is the gravitational energy of the system. The agreement between our numerical solutions with known analytical as well as… Expand

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#### References

SHOWING 1-10 OF 29 REFERENCES

Rotational properties of composite polytrope models

- Physics
- 1988

Factional radii of gyration for both the convective envelope and the radiative core have been determined using the composite-polytrope model of Rappaport et al. (1983) which describes low-mass stars… Expand

Analytical representations for simple and composite polytropes and their moments of inertia

- Physics
- 2015

Abstract Polytropes are widely applied in astrophysics. To facilitate their use, we derive analytical formulae for the moment of inertia as a function of polytropic index. We also provide 1- and… Expand

Numerical Methods for the Simulation of Dynamical Mass Transfer in Binaries

- Physics
- 2002

We describe computational tools that have been developed to simulate dynamical mass transfer in semidetached, polytropic binaries that are initially executing synchronous rotation upon circular… Expand

A new technique for calculations of binary stellar evolution, with application to magnetic braking

- Physics
- 1983

We present a new computational technique for the study of the evolution of compact binary stellar systems with mass-losing secondaries whose masses can range between approx.0.01 M/sub sun/ and… Expand

A double polytropic model for low-mass stars

- Physics
- 1988

A double polytropic model is presented for the low-mass stars withM<M⊙. The essential novelty of our approach is the description of the convective envelope, which is taken as ann=1 polytrope. This… Expand

A small contribution to the giant problem

- Physics
- 1998

We present a simple analytic model of a composite polytropic star, which exhibits a limiting Scho¨nberg–Chandrasekhar core mass fraction strongly analogous to the classic numerical result for an… Expand

The fast spin-rotation of a young extrasolar planet

- Physics
- 2014

The spin-rotation of a planet arises from the accretion of angular momentum during its formation, but the details of this process are still unclear. In the solar system, the equatorial rotation… Expand

Angular momentum in stars - The Kraft curve revisited

- Physics
- 1987

The author has rederived the relationship between angular momentum and stellar mass for stars earlier than F0 using current stellar models and rotational velocities. The form of the relationship is… Expand

An Introduction to the Study of Stellar Structure

- Physics
- Nature
- 1939

EDDINGTON'S “Internal Constitution of the Stars” was published in 1926 and gives what now ranks as a classical account of his own researches and of the general state of the theory at that time. Since… Expand

Theory of rotating stars

- Physics
- 1978

Ever since the first observations of sunspots in the early seventeenth century, stellar rotation has been a major topic in astronomy and astrophysics. Jean-Louis Tassoul synthesizes a large number of… Expand