**Research papers: Galactic Dynamics**

**Mass Distributions of 5 Hypothetical Disk Galaxies**

From the shapes of 5 idealised disk galaxy rotation curves, this project calculates their mass distributions.

Read PDF

**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.

Read PDF

**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.

Read PDF

**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.

Read PDF

**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.

Read PDF

**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.

Read PDF

**Galactic bars in power-law fields**

Elongated bars in simple power-law fields are shown to have retrograde pattern rotation.

Read PDF

**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).

Read PDF

**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.

Read PDF

**Predicted kinematics of the enigmatic galaxy NGC 3450**

A theoretical model of NGC 3450 in which the bar and disk co-precess.

Read PDF

**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?

Read PDF

**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.

Read PDF

**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.

Read PDF

**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.

Read PDF

**Nested Elliptic Orbits in a Linear Force Field**

Calculation of the isovelocity contours, and of the velocity profiles on the major and minor axes.

Read PDF

**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.

Read PDF

**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.

Read PDF

**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.

Read PDF