Volume 396, Number 1, December II 2002
|Page(s)||73 - 81|
|Section||Cosmology (including clusters of galaxies)|
|Published online||22 November 2002|
A 60 pc counter-rotating core in NGC 4621*
Centre de Recherche Astronomique de Lyon, 9 Av. Charles André, 69561 Saint-Genis Laval Cedex, France
2 Institut de physique nucléaire de Lyon, 4 rue Enrico Fermi, 69622 Villeurbanne Cedex, France
Corresponding author: F. Wernli, email@example.com
Accepted: 10 September 2002
We present adaptive optics assisted OASIS integral field spectrography of the S0 galaxy NGC 4621. Two-dimensional stellar kinematical maps (mean velocity and dispersion) reveal the presence of a ~60 pc diameter counter-rotating core (CRC), the smallest observed to date. The OASIS data also suggests that the kinematic center of the CRC is slightly offset from the center of the outer isophotes. This seems to be confirmed by archival HST/STIS data. We also present the HST/WFPC2 colour map, which exhibits a central elongated red structure, also slightly off-centered in the same direction as the kinematic centre. We then construct an axisymmetric model of NGC 4621: the two-integral distribution function is derived using the Multi-Gaussian Expansion and the Hunter & Qian ([CITE]) formalisms. Although the stellar velocities are reasonably fitted, including the region of the counter-rotating core, significant discrepancies between the model and the observations demonstrate the need for a more general model (e.g. a three-integral model).
Key words: galaxies: elliptical and lenticular, cD / galaxies: evolution / galaxies: individual: NGC 4621 / galaxies: formation / galaxies: kinematics and dynamics / galaxies: nuclei
© ESO, 2002
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.