2005ApJ...634..281H

We present measurements of the stellar velocity dispersion in the inner 1' radius (1.3 disk scale lengths) of the irregular galaxy NGC 4449 determined from long-slit absorption-line spectra. The average observed dispersion is 29±2 km/s, the same as predicted from NGC 4449's luminosity. No significant rotation in the stars is detected. If we assume a maximum rotation speed of the stars from the model determined from the gas kinematics of Hunter et al., the ratio V_max/σ_zmeasured globally is 3. This ratio is comparable to values measured in spiral galaxies and implies that the stellar disk in NGC 4449 is kinematically relatively cold. The intrinsic minor-to-major axis ratio (b/a)₀is predicted to be in the range 0.3-0.6, similar to values derived from the distribution of observed b/a of Im galaxies. However, V/σ_z measured locally is 0.5-1.1, and so the circular velocity of NGC 4449 is comparable to or less than the velocity of the stars within the central 1.3 disk scale lengths of the galaxy.