Figure 8. Illustration of the luminosity of the spiral arms changes with the rotation angle with µ = 6. The letter A marks the half loop rotation angle 216°, the letter B marks the full loop rotation angle. 432°. The right side is the half image of side view of Milky Way showing the thickness and density of the disc decreasing with radius

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How Long Can the Spiral Arms of Disc Galaxies Be Optically Observed?

Hongjun Pan

International Journal of Physics. 2024, 12(5), 212-224 doi:10.12691/ijp-12-5-4