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Research papers: Galactic Dynamics

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Mass Distributions of 5 Hypothetical Disk Galaxies
From the shapes of 5 idealised disk galaxy rotation curves, this project calculates their mass distributions.
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Calculation of mass distribution and total mass of galaxies from their rotation curves
A bibliography of papers on the calculation of the mass distribution and the total mass of galaxies, from their rotation curves, using only Newton's theory of gravitational attraction, and without requiring non-baryonic matter.
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Proposed solution of the winding problem in galactic dynamics
It is proposed that an ellipticity gradient of the orbit streamlines of a galactic disk produces co-precession throughout the disk, eliminating the winding problem.
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A predicted orbital ellipticity gradient in the disk of the Milky Way
Proposes that orbits in the main part of the milky way disk have ellipticities which decrease with increasing orbit size.
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Video Animation of an Orbital Streamline in the Disk of a Galaxy
Possibly the only video available anywhere which illustrates a precessing orbital streamline in a galactic disk.
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Theoretical Dynamics of Nested Galactic Bars
This computer study of self-similar outer and inner bars in galaxies shows how the ratio of their absolute pattern rotation rates is determined by the scale factor and the power-law exponent. Proposes that the inner bar has a slower absolute pattern rotation rate than the outer bar.
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Galactic bars in power-law fields
Elongated bars in simple power-law fields are shown to have retrograde pattern rotation.
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Major-axis velocity profiles of galactic bars
A new interpretation, of the observed lineally rising major-axis velocity profile in the bar of many barred galaxies, indicates that the gravitational field is in the range (x>1).
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Trailing or leading spiral arms
Single-armed and two-armed spiral density waves are examined in four ranges of simple power-law fields and the trailing or leading senses of the arms are determined.
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Predicted kinematics of the enigmatic galaxy NGC 3450
A theoretical model of NGC 3450 in which the bar and disk co-precess.
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Predicted kinematics of NGC 3124
NGC 3124 has two spiral arms in the bar which open in the opposite sense to the spiral arms of the disk. Are the bar's spiral arms trailing or leading?
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Co-precession
Examines systems of coplanar nested orbit streamlines in galaxies, and aims to explain how it is possible for every streamline to share the same precession rate.
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The Inner Lindblad Resonance in Galactic Dynamics
Demonstrates that in any co-precessing set of orbits, all the orbits are in inner lindblad resonance with each other.
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The Velocity of a Centred Elliptical Orbit
Velocities at pericentre and apocentre of elliptic orbits, in a central gravity field where gravitational acceleration towards the centre is proportional to distance from the centre.
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Nested Elliptic Orbits in a Linear Force Field
Calculation of the isovelocity contours, and of the velocity profiles on the major and minor axes.
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Equalisation of precession rates of galactic orbits (Part 1)
Using software which calculates precession rates of galactic orbits, a complete galactic component is constructed in the f∝√d field. It is proposed that interacting galactic orbits may adjust their ellipticities to equalise their precession rates.
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Equalisation of precession rates of galactic orbits (Part 2)
A complete galactic component of uniform retrograde precession rate is constructed in the f∝d^2 field. The component has inner and outer boundaries, and is scale-free, so there may be multiple instances of the component, at various scales, nested within each other, each instance of the component having a different pattern speed.
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Equalisation of precession rates of galactic orbits (Part 3)
In a disk galaxy, two ranges of simple power-law fields are examined. It is proposed that one range of fields produces galactic components with positive ellipticity gradient and retrograde pattern speed, and that the other range of fields produces galactic components with negative ellipticity gradient and prograde pattern speed. Some isophotal examples are referred to.
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