A counterrotating core in IC 1459

Franx, M. & Illingworth, G.D. 1988, Ap. J. 327, L55.

The radio elliptical IC 1459 is shown to have a massive rapidly counterrotating stellar core. Along the major axis a strong peak in the rotational velocity is observed at a distance of 2 arcsec (0.3 kpc) from the center. The velocity reaches 170 + or - 20 km/s. The rotational velocity in the outer parts rises to 45 + or - 8 km/s, but in the opposite sense to the rotation of the center. Along the minor axis, no significant rotation is measured, neither in the center nor in the outer parts. Line profiles derived from cross-correlated spectra along the major axis in the core show a clear asymmetry. Ionized gas rotates around the minor axis in the same sense as the outer part of the galaxy. The other properties are typical of normal ellipticals. The galaxy has a regular color gradient and line strength gradient. The mass of the counterrotating component is estimated to be about 10 to the 10th solar masses. It is postulated that such a core could form, following the merger of two galaxies, either by the tidal disruption of the victim or through a starburst-like event.