Article
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How Long Can the Spiral Arms of Disc Galaxies Be Optically Observed?
Version 1
: Received: 1 November 2023 / Approved: 2 November 2023 / Online: 2 November 2023 (10:34:43 CET)
How to cite: Pan, H. How Long Can the Spiral Arms of Disc Galaxies Be Optically Observed?. Preprints 2023, 2023110134. https://doi.org/10.20944/preprints202311.0134.v1 Pan, H. How Long Can the Spiral Arms of Disc Galaxies Be Optically Observed?. Preprints 2023, 2023110134. https://doi.org/10.20944/preprints202311.0134.v1
Abstract
The study on the temporal duration of optically observed spiral patterns in disc galaxies is based on the finite reservoir of hydrogen available with no replenishment following the initial formation of these well-isolated galaxies. The results reveal a gradual decline in observable spiral arms regardless of any spiral arm formation mechanism. This reduction occurs after half-loop rotations (as defined in the paper) as hydrogen reserves deplete, hindering new star formation. Ultimately, spiral patterns may possibly become optically invisible at normal conditions after a full-loop rotation (as defined in the paper) due to hydrogen depletion, even if the formation mechanism remains active. This supports the idea of short-lived spiral patterns compared to the lifespan of the spiral galaxies. The spiral arm formation may occur once in a galaxy's life based on the limited availability of hydrogens. A concise, universally applicable mechanism for spiral arm formation across various disc galaxies should exist which provides a single mathematical formula to describe the broad range of morphologies of the spiral arms with few adjustable parameters. Some exceptions may be explained within this framework. Furthermore, the observed data on spiral pattern and galactic bar rotation speeds in the Milky Way require rigorous verification, particularly concerning the winding problem.
Keywords
Spiral arms; spiral pattern rotation; evolution; spiral galaxies
Subject
Physical Sciences, Astronomy and Astrophysics
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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