Velocity dispersions in galaxies. VI. Comparison of the nucleus and bulge of M31.

Velocity dispersions in both the nucleus (r < 3") and the bulge (3" < r < 300") of M31 have been estimated from a coude' spectrum obtained with an SEC television sensor. Comparison with standard giant stars from G8 III to K3 III gives line-of-sight dispersions aN = 120 in the nucleus and aB = 110 km 1 in the bulge, each with uncertainties of about +20 km 1 Comparison of the bulge with the nucleus shows that a /a probably lies between 0.83 and 1.17. A ratio near unity was not expected since any simple two-component model, such as that developed by Ruiz, requires that the bulge stars have a significantly larger dispersion to avoid being caught in the deep potential well of the nucleus. Subject headings: galaxies: individual - galaxies: internal motions - galaxies: nuclei