Kinematics and stellar population of NGC 4486A

¹ Université de Lyon, Université Lyon 1, 69622 Villeurbanne, France ; CRAL, Observatoire de Lyon, CNRS UMR 5574, 69561 Saint-Genis Laval France
e-mail: philippe.prugniel@univ-lyon1.fr
² Institut für Astronomie, Universität Wien, Türkenschanzstraße 17, 1180 Wien, Austria
e-mail: werner.zeilinger@univie.ac.at
³ Instituto de Astrofísica de Canarias, La Laguna, 38200 Tenerife ; Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
e-mail: koleva@iac.es
⁴ Dept. of Physics & Astronomy, Ghent University, Krijgslaan 281, S9, 9000 Ghent, Belgium
e-mail: sven.derijcke@ugent.be

Received: 17 December 2010
Accepted: 2 February 2011

Abstract

Context. NGC 4486A is a low-luminosity elliptical galaxy harbouring an edge-on nuclear disk of stars and dust. It is known to host a super-massive black hole.

Aims. We study its large-scale kinematics and stellar population along the major axis to investigate the link between the nuclear and global properties.

Methods. We use long-slit medium-resolution optical spectra that we fit against stellar population models.

Results. The SSP-equivalent age is about 12 Gyr old throughout the body of the galaxy, and its metallicity decreases from [Fe/H] = 0.18 near the centre to sub-solar values in the outskirts. The metallicity gradient is  −0.24 dex per decade of radius within the effective isophote. The velocity dispersion is 132 ± 3 km s^-1 at 1.3″ from the centre and decreases outwards. The rotation velocity reaches a maximum  km s^-1 at a radius 1.3 < r_max < 2″.

Conclusions. NGC 4486A appears to be a typical low-luminosity elliptical galaxy. There is no signature in the stellar population of the possible ancient accretion/merging event that produced the disk.