Hostname: page-component-586b7cd67f-dlnhk Total loading time: 0 Render date: 2024-11-30T03:40:56.545Z Has data issue: false hasContentIssue false
  • English
  • Français

Radial Motions Near the Galactic Centre and the Origin of Galactic Spiral Structure

Published online by Cambridge University Press:  12 April 2016

Th. Schmidt-Kaler
Th. Schmidt-Kaler*
Affiliation:
Astronomisches Institut der Ruhr-Universitãt Bochum

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The fundamental difficulty of explaining the spiral structure of galaxies by material arms is the winding dilemma which restricts the life-time of a spiral to about one rotation period. This dilemma is resolved by the density wave concept. However, the density waves are damped by various processes. We calculated the life time of the density wave for our Galaxy (τ = 8.108 yrs) as well as for 24 nearby spiral galaxies with well-known data. It appears that the density wave can explain the existence of spiral arms for only about three rotation periods. After that time the energy of the wave has to be re-supplied. For this, various mechanisms have been proposed, e.g.

  • 1) tidal origin – which requires rather special circumstances

  • 2) resonant interaction – which is energetically insufficient

  • 3) local Jeans-type instability in the outer regions – which also may not be able to provide sufficient energy

  • 4) explosions of the nucleus – which involve high inclinations to the plane.

Type
Part II: Evolution of the Central Parts of the Galaxy
Information
International Astronomical Union Colloquium , Volume 45: Chemical and Dynamical Evolution of our Galaxy , September 1977 , pp. 125 - 129
Copyright
Copyright © Geneva Observatory 1977

References

Bryan, G.H.: 1888, Acta Math. 7, 187.Google Scholar
Chandrasekhar, S.: 1969, Ellipsoidal Figures of Equilibrium, Yale University Press, New Haven.Google Scholar
Cohen, R.J. and Davies, R.D.: 1976, Monthly Notices Roy. Astron. Soc. 175, 1.CrossRefGoogle Scholar
Dirichlet, G.L.: 1860 J. reine und angewandte Mathematik 58, 181.Google Scholar
Feitzinger, J. and Schmidt-Kaler, Th.: 1977, in preparation.Google Scholar
Feldman, S.I. and Lin, C.C.: 1973, Studies Appl. Math. 52, 1.CrossRefGoogle Scholar
Lyttleton, R.A.: 1953, The Stability of Rotating Liquid Masses, Cambridge University Press, Cambridge.Google Scholar
Riemann, B.: 1860, Abh. Königl. Ges. Wiss. Göttingen 9, 3.Google Scholar
Rohlfs, K., Schmidt-Kaler, Th.: 1977, in preparation.Google Scholar
Rossner, L.F.: 1967, Astrophys. J. 19, 145.CrossRefGoogle Scholar
Schmidt-Kaler, Th.: 1973, Vistas in Astronomy, 149, 69.Google Scholar
Schmidt-Kaler, Th.: 1975, Optische Beobachtungsprogramme zur galaktischen Struktur und Dynamik, Bochum (Ed.: Schmidt-Kaler, Th.) 75.Google Scholar
Wiegandt, R.: 1977, in preparation.Google Scholar
Yuan, Ch.: 1977, private communication.Google Scholar