Forum Springer Astron. Astrophys.
Forum Whats New Search Orders

Astron. Astrophys. 341, 357-360 (1999)

Table of Contents
Available formats: HTML | PDF | (gzipped) PostScript

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

1 Osservatorio Astronomico di Brera, Via Brera 28, I-20121 Milano, Italy
2 Dipartimento di Astronomia, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy
3 Institut d'Astrophysique, 98 bis, Boulevard Arago, F-75014 Paris, France
4 Istituto di Fisica Applicata, Università di Milano, Via Brera 28, I-20121 Milano, Italy

Received 6 April 1998 / Accepted 29 October 1998


Using two line-strength indices, H+K(CaII) and [FORMULA], 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 [FORMULA] indices.

By enlarging their sample with the present one, we find that the significance of the correlation [FORMULA] 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

© European Southern Observatory (ESO) 1999

Online publication: December 4, 1998