Stellar Kinematics for the Central Spheroid in the Polar Disk Galaxy NGC 4650A

Type Journal Article
Names E. Iodice, M. Arnaboldi, R. P. Saglia, L. S. Sparke, O. Gerhard, J. S. Gallagher, F. Combes, F. Bournaud, M. Capaccioli, K. C. Freeman
Publication The Astrophysical Journal
Volume 643
Issue 1
Pages 200-209
Date May 1, 2006
URL http://adsabs.harvard.edu/abs/2006ApJ...643..200I
Library Catalog NASA ADS
Abstract We have obtained high angular resolution, high signal-to-noise ratio spectra of the calcium triplet absorption lines on the photometric axes of the stellar spheroid in the polar disk galaxy NGC 4650A. Along the major axis, the observed rotation and velocity dispersion measurements show the presence of a kinematically decoupled nucleus and a flat velocity dispersion profile. The minor-axis kinematics is determined for the first time: along this direction some rotation is measured, and the velocity dispersion is nearly constant and slightly increases at larger distances from the center. The new high-resolution kinematic data suggest that the stellar component in NGC 4650A resembles a nearly exponential oblate spheroid supported by rotation. The main implications of these results on the previous mass models for NGC 4650A are discussed. Moreover, the new kinematic data set constraints on current models for the formation scenarios of polar ring galaxies, supporting a slow accretion rather than a secondary strong dissipative event. Based on data collected with the FORS2 spectrograph, mounted at the UT4 of the Very Large Telescope at Cerro Paranal, Chile, operated by ESO, during observing run 70.B-0277.
Tags Galaxies: Individual: NGC Number: NGC 4650A, galaxies: kinematics and dynamics
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