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Astron. Astrophys. 335, 49-52 (1998)

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Color distributions in E-S0 galaxies

III. E-objects with "power-law" or "core-like" central profiles *

R. Michard

Observatoire de la Cote d'Azur, Département Augustin Fresnel B.P. 229, F-06304 Nice Cedex 4, France Observatoire de Paris, DEMIRM, 77 av. Denfert-Rochereau, F-75015 Paris, France

Received 27 January 1998 / Accepted 16 March 1998


Measurements of the central red color peak occurring in E-type galaxies have been obtained from Nieto's CFHT observations in B and R of 39 objects. A careful equalization of the PSF of the two frames involved in color maps and profiles was crucial in achieving significant results, although still affected by limited resolution. The class of the central light profile, i.e. "core-like" or "power-law", was also derived.

The well known correlation between the class of central profile and the large scale morphology is somewhat improved. The distributions of central red peak amplitudes are obtained separately for the two classes of central profiles, and shown to be quite different; most objects with a core-like center also have a flat central color profile. The model of Silva & Wise (1996), for the production of broad cores by centrally located diffuse dust, is not supported. This is in agreement with recent HST results by Carollo et al. (1997) from a special subsample of objects with kinematically decoupled cores.

Key words: galaxies: elliptical and lenticular, cD – galaxies: ISM – galaxies: photometry

* Based on observations collected at the Canada-France-Hawaii Telescope and at the Observatoire du Pic du Midi

Send offprint requests to: R. Michard

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© European Southern Observatory (ESO) 1998

Online publication: June 12, 1998