Stellar Counter-Rotation Along the Hubble Sequence: A Probe for Galaxy Formation Scenarios

Prada, F.; Gutiérrez, C. M.
Referencia bibliográfica

Galaxy Interactions at Low and High Redshift, Proceedings of IAU Symposium #186, held at Kyoto, Japan, 26-30 August, 1997. Edited by J. E. Barnes, and D. B. Sanders, 1999., p.161

Fecha de publicación:
0
1999
Número de autores
2
Número de autores del IAC
0
Número de citas
0
Número de citas referidas
0
Descripción
There is an increasing observational evidence of the presence of retrograde motions in ellipticals and early type spiral galaxies. However, little is known about this phenomenon in barred and late ordinary spirals. Here, we present the current status of an on-going research programme at the Observatorio del Roque de los Muchachos (La Palma) to establish the presence and nature of the counterrotating phenomenon across the Hubble sequence. We report the discovery of a warm counterrotating component in the central regions of the late spiral NGC 7331 and the barred NGC 5728 galaxies. The stellar line-of-sight velocity distribution was determined using near-IR long-slit spectroscopy of the calcium triplet absorption feature with the William Herschel Telescope. In NGC 7331 we find the first case of a counterrotating bulge, while in NGC 5728 a central counterrotating component was discovered in a barred galaxy. These results show that retrograde motion extends throughout the Hubble sequence. The implications of this in the context of the theories of galaxy formation are discussed.