User:Tohline/Apps/RotatingPolytropes

Rotationally Flattened Polytropes

Example Equilibrium Configurations

Reviews

• N. R. Lebovitz (1967), ARAA, 5, 465

Uniform Rotation

• E. A. Milne (1923), MNRAS, 83, 118: The Equilibrium of a Rotating Star

Apparently, only n = 3 polytropic configurations are considered.

• H. von Zeipel (1924), MNRAS, 84, 665: The radiative equilibrium of a rotating system of gaseous masses
• H. von Zeipel (1924), MNRAS, 84, 684: The radiative equilibrium of a slightly oblate rotating star
• S. Chandrasekhar (1933), MNRAS, 93, 390: The equilibrium of distorted polytropes. I. The rotational problem

The purpose of this paper is … to extend Emden's [work] to the case of rotating gas spheres which in their non-rotating states have polytropic distributions described by the so-called Emden functions. … the gas sphere is set rotating at a constant small angular velocity <math>~\omega</math>. … we shall assume that the rotation is so slow that the configurations are only slightly oblate.

• S. Chandrasekhar & N. R. Lebovitz (1962), ApJ, 136, 1069

If one assumes that the mass is distributed uniformly, the equilibrium configurations are the well-known Maclaurin spheroids. This paper will be devoted to finding the oscillation frequencies of the Maclaurin spheroids.

• P. H. Roberts (1963a), ApJ, 137, 1129: On Highly Rotating Polytropes. I.
• P. H. Roberts (1963b), ApJ, 138, 809: On Highly Rotating Polytropes. II.
• R. A. James (1964), 140, 552: The Structure and Stability of Rotating Gas Masses

Structures have been determined for axially symmetric [uniformly] rotating gas masses, in the polytropic and white-dwarf cases … Physical parameters for the rotating configurations were obtained for values of n < 3, and for a range of white-dwarf configurations. The existence of forms of bifurcation of the axially symmetric series of equilibrium forms was also investigated. The white-dwarf series proved to lack such points of bifurcation, but they were found on the polytropic series for n < 0.808.

• F. F. Monaghan & I. W. Roxburgh (1965), MNRAS, 131, 13: The structure of rapidly rotating polytropes

James attacked the problem by numerically solving the partial differential equations of the problem with the aid of an electronic computer, but even this method lead to difficulties for <math>~n \ge 3</math>. Of all the methods used so far James' is undoubtedly the most accurate, but also the most laborious. Here, results are presented for values of the polytropic index n = 1, 1.5, 2, 2.5, 3, 3.5, 4. (Apparently, uniform rotation is assumed.) … no discussion of stability is given, we assume that the polytropes become unstable at the equator before a point of bifurcation is reached.

• J. - L. Tassoul & J. P. Ostriker (1970), Astron. Ap., 4, 423: Secular Stability of Uniformly Rotating Polytropes
• N. R. Lebovitz & G. W. Russell (1972), ApJ, 171, 103: The Pulsations of Polytropic Masses in Rapid, Uniform Rotation
• M. J. Clement (1981), ApJ, 249, 746: Normal modes of oscillation for rotating stars. I — The effect of rigid rotation on four low-order pulsations

In this paper, the effects of rigid rotation on four axisymmetric modes are found for several equilibrium systems including polytopes and a 15 solar-mass stellar model. Normal modes are determined by solving directly on a two-dimensional grid the linearized dynamical equations governing adiabatic oscillations … This brute force approach has many obvious dangers, all of which are realized in practice.

Differential Rotation

• S. Chandrasekhar & N. R. Lebovitz (1962), ApJ, 136, 1082

The oscillations of slowly rotating polytopes are treated in this paper. The initial equilibrium configurations are constructed as in Chandrasekhar (1933).

• TORUS! J. P. Ostriker (1964), ApJ, 140, 1067: The Equilibrium of Self-Gravitating Rings
• R. Stoeckly (1965), ApJ, 142, 208: Polytropic Models with Fast, Non-Uniform Rotation [NOTE: Article not available via SAO/NASA ADS.]

Models with polytropic index n = 1.5.… for the case of non-uniform rotation, no meridional currents, and axial symmetry. The angular velocity assigned … is a Gaussian function of distance from the axis. The exponential constant <math>~c</math> in this function is a parameter of non-uniformity of rotation, ranging from 0 (uniform rotation) to 1 (approximate spatial dependence of angular velocity that might arise during contraction from a uniformly rotating mass of initially homogeneous density). For <math>~c = 0</math>, a sequence of models having increasing angular momentum is known to terminate when centrifugal force balances gravitational force at the equator; this sequence contains no bifurcation point with non-axisymmetric models as does the sequence of Maclaurin spheroids with the Jacobi ellipsoids. For <math>~c \approx 1</math>, the distortion of interior equidensity contours of some models with fast rotation is shown to exceed that of the Maclaurin spheroids at their bifurcation point. In the absence of a rigorous stability investigation, this result suggests that a star with sufficiently non-uniform rotation reaches a point of bifurcation … Non-uniformity of rotation would then be an element bearing on star formation and could be a factor in double-star formation.

• J. P. Ostriker & P. Bodenheimer (1973), ApJ, 180, 171 [Part III]: On the Oscillations and Stability of Rapidly Rotating Stellar Models. III. Zero-Viscosity Polytropic Sequences
• P. Bodenheimer & J. P. Ostriker (1973), ApJ, 180, 159 [Part VIII]

An explanation is given regarding the specification of various so-called <math>~n'</math> angular momentum distributions. Equilibrium models are built along the following <math>~(n, n')</math> sequences:  <math>~(0, 0)</math>, <math>~(\tfrac{3}{2}, \tfrac{3}{2})</math>, <math>~(\tfrac{3}{2}, 1)</math>, <math>~(\tfrac{3}{2}, 0)</math>, <math>~(3, 0)</math>, and <math>~(3, \tfrac{3}{2})</math>.

• J. L. Friedman & B. F. Schutz (1978), ApJ, 222, 281
• R. H. Durisen & J. N. Imamura (1981), ApJ, 243, 612
• J. E. Tohline, R. H. Durisen & M. McCollough (1985), ApJ, 298, 220
• R. H. Durisen, R. A. Gingold, J. E. Tohline & A. P. Boss (1986), ApJ, 305, 281
• H. A. Williams & J. E. Tohline (1987), ApJ, 315, 594
• H. A. Williams & J. E. Tohline (1988), ApJ, 334, 449
• P. J. Luyten (1990), MNRAS, 245, 614
• P. J. Luyten (1991), MNRAS, 248, 256
• A. G. Aksenov (1996), Astronomy Letters, 22, 634
• B. K. Pickett, R. H. Durisen & G. A. Davis (1996), ApJ, 458, 714
• B. K. Pickett, R. H. Durisen & R. Link (1997), Icarus, 126, 243
• J. Toman, J. N. Imamura, B. K. Pickett & R. H. Durisen (1998), ApJ, 497, 370
• J. N. Imamura, R. H. Durisen & B. K. Pickett (2000), ApJ, 528, 946
• J. M. Centrella, K. C. B. New, L. L. Lowe & J. D. Brown (2001), ApJL, 550, 193
• M. Shibata, S. Karino & Y. Eriguchi (2002), MNRAS, 334, 27
• M. Saijo, T. W. Baumgarte & S. L. Shapiro (2003), ApJ, 595, 352
• M. Saijo & S. Yoshida (2006), MNRAS, 368, 1429

See Also

• Our discussion of Rotating White Dwarfs: Example Equilibria
• Fission Theory of Binary Star Formation

© 2014 - 2021 by Joel E. Tohline |   H_Book Home   |   YouTube   | Appendices: | Equations | Variables | References | Ramblings | Images | myphys.lsu | ADS | Recommended citation:   Tohline, Joel E. (2021), The Structure, Stability, & Dynamics of Self-Gravitating Fluids, a (MediaWiki-based) Vistrails.org publication, https://www.vistrails.org/index.php/User:Tohline/citation