Radial migration of the Sun in galactic disk

TL;DR

This paper models the gravitational effects of galactic structures on the Sun's radial migration, finding it remains mostly within 0.4 kpc for four-armed spirals and varies more with two-armed spirals, influencing galaxy structure interpretations.

Contribution

It introduces a new physical model with different equations to analyze the Sun's radial migration considering galactic bar and spiral structure effects.

Findings

Radial migration of the Sun is less than ±0.4 kpc for four-armed spirals.

Migration is between ±0.3 and 1.2 kpc for two-armed spirals.

The Sun mostly remains within 7.8-8.2 kpc from the galactic center.

Abstract

Physics of the gravitational effect of the galactic bar and spiral structure is presented. Physical equations differ from the conventionally used equations. Application to the motion of the Sun is treated. The speed of the Sun is taken to be consistent with the Oort constants. Galactic radial migration of the Sun is less than +- 0.4 kpc for the four-armed spiral structure. The Sun remains about 75 % of its existence within galactocentric distances (7.8 - 8.2) kpc and the results are practically independent on the spiral structure strength. Thus, the radial distance changes only within 5 % from the value of 8 kpc. Galactic radial migration of the Sun is less than +- (0.3 - 1.2) kpc, for the two-armed spiral structure. The Sun remains (29 - 95) % of its existence within galactocentric distances (7.8 - 8.2) kpc and the results strongly depend on the spiral structure strength and the angular speed of the spiral arms. The radial distance changes within (3.8 - 15.0) % from the value of 8 kpc. If observational arguments prefer relevant radial migration of the Sun, then the Milky Way is characterized by the two-arm spiral structure.