Near-infrared surface photometry of early-type galaxies

¹ Departamento de Astronomia, Instituto de Física, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, CP 15051, 91501-970 Porto Alegre, Brazil e-mail: rembold@if.ufrgs.br;mgp@if.ufrgs.br;ducati@if.ufrgs.br
² Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile e-mail: mrubio@das.uchile.cl
³ Carnegie Institution of Washington, Las Campanas Observatory, Casilla 601, La Serena, Chile e-mail: mroth@lco.cl

Corresponding author: S. B. Rembold, rembold@if.ufrgs.br

Received: 24 April 2002
Accepted: 23 May 2002

Abstract

CCD infrared (JHK_s) photometry was performed on a sample of 10 elliptical and 2 lenticular galaxies. Isophotal parameters, brightness profiles, integrated colors and color gradients are presented. Color gradients found are very weak, showing bluer colors towards the outer regions. The colors of the sample galaxies are compatible with stellar populations like those found in metal-rich clusters of the Galaxy; objects NGC 7192, NGC 7562 and NGC 7619 are compatible with less metal-rich populations. The brightness profile of most galaxies is well described by the law. The profiles of NGC 1600 and NGC 720 are described by Sérsic's law with and respectively. The infrared effective radius of the objects studied is typically one half of its counterpart in the B band, which can be an indication that the stellar population that dominates the infrared emission is more concentrated in the central regions. We show that the sample satisfies the Fundamental Plane relation of elliptical galaxies in the infrared, with an rms scatter of 0.20 for J and H and 0.23 for K_s.