Central K-band kinematics and line strength maps of NGC 1399^*

¹ ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany e-mail: mlyubeno@eso.org
² Space Telescope European Coordinating Facility, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany e-mail: hkuntsch@eso.org
³ National Optical Astronomy Observatory, 950 North Cherry Ave., Tucson, AZ, 85748, USA e-mail: dsilva@tmt.org

Received: 21 December 2007
Accepted: 12 March 2008

Abstract

In this paper we present for the first time high spatial resolution K-band maps of the central kinematical and near-infrared spectral properties of the giant cD galaxy in the Fornax cluster, NGC 1399. We confirm the presence of a central velocity dispersion dip within seen in previous long-slit studies. Our velocity dispersion maps give evidence of a non-symmetric structure in this central area by showing three σ peaks to the north-east, south-east and west of the galaxy centre. Additionally we measure near-IR line strength indices at unprecedented spatial resolution in NGC 1399. The most important features we observe in our 2-dimensional line strength maps are drops in Na I and CO (2–0) line strength in the nuclear region of the galaxy, coinciding spatially with the drop in σ. The observed line strength and velocity dispersion changes suggest a scenario where the centre of NGC 1399 harbours a dynamically cold subsystem with a distinct stellar population.