Abstract
IT has long been known1–3 that the flattest elliptical galaxies observed are of type E7, corresponding to an axial ratio of 3.33:1 whereas SO and spiral galaxies are seen with axial ratios up to 20:1. We show, using Maclaurin spheroid models, that an initially spherical protogalaxy, composed entirely of stars, will always relax after a dissipationless collapse to an equilibrium configuration with ɛ ≡ 1−(c/a) ⩽ 0.70925, where a,c are the semi-major, semi-minor axes. This happens regardless of original angular momentum of the galaxy, and is in remarkable agreement with the maximum observed flattening of elliptical galaxies.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Hubble, E. P., Realm of the Nebulae (Yale University Press, New Haven, 1936).
de Vaucouleurs, G., IAU Symp. No. 58 (edit. by Shakeshaft, J. R.,) (1974).
Sandage, A., Freeman, K. C., and Stokes, N. R., Astrophys. J., 160, 831 (1970).
Peebles, P. J. E., Astrophys. J., 155, 393 (1969).
Ozernoi, L. M., and Chernin, A. D., Soviet Astr., 11, 907 (1968).
Lynden-Bell, D., Mon. Not. R. astr. Soc., 136, 101 (1967).
Peebles, P. J. E., Astr. J., 75, 13 (1970).
Gott, J. R., III, Astrophys. J. (in the press).
King, I., Astr. J., 71, 64 (1966).
Chandrasekhar, S., Ellipsoidal Figures of Equilibrium (Yale University Press, New Haven, 1969).
Bouvier, P., and Janin, G., Astr. Astrophys., 5, 127 (1970).
Ostriker, J. P., and Peebles, P. J. E., Astrophys. J., 186, 467 (1973).
Gott, J. R., III, and Thuan, T. X., Astrophys. J. (in the press).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
THUAN, T., GOTT, J. Why there are no elliptical galaxies flatter than E7. Nature 257, 774–776 (1975). https://doi.org/10.1038/257774a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/257774a0
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.
