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Star formation history of early-type galaxies in low density environments
III. The isophote shape parameter and nuclear line-strength indices
R. Rampazzo 1,
M. D'Onofrio 2,
P. Bonfanti 1,
M. Longhetti 3 and
L. Reduzzi 4
Received 6 April 1998 / Accepted 29 October 1998
Using two line-strength indices, H+K(CaII) and , sensible to the age of the stellar population, we analyze the correlations between the shape and the `galaxy age' suggested by de Jong & Davies (1997) on the basis that discy galaxies have higher indices.
By enlarging their sample with the present one, we find that the significance of the correlation vs. line- strength indices disappears.
We conclude that the `age of the stellar population of early-type galaxies' is not correlated to the isophote shape parameter.
Key words: galaxies: elliptical and lenticular, cD galaxies: evolution galaxies: formation galaxies: fundamental parameters galaxies: interactions
Send offprint requests to: R. Rampazzo
Online publication: December 4, 1998