De Vaucouleurs Atlas Type: (R2')SAB(s)ab
Telescope: McGraw-Hill 1.3-m
North up , East left
Field Dimensions: 8.7 x 8.0 arcminutes
RC3 Type: (R')SAB(rs)ab:
RSA Type: Sab
Surface Brightness Range Displayed: 16.5-26.0 mag per square arcsec
Absolute Blue Magnitude: -20.8
Elmegreen Spiral Arm Class: AC 5
De Vaucouleurs Atlas Description:
The morphology of the bright inner regions of this famous Seyfert 1 galaxy is unusual. From the outer arms, the galaxy is clearly almost face-on, thus the oval inner zone is a bar-like feature. This is the basis of the SAB classification. It differs from cases where the SAB classification is adopted simply because a conventional bar is weak. The oval zone of NGC 4151 is unusual because it includes strange ``ansae " defined by collections of star-forming regions. In most barred galaxies, ansae are largely stellar dynamical in nature. The image we show reveals weak dust lanes in the main oval and a smaller inner oval aligned perpendicular to the main one. This feature was also noted by others. Our image does not show the faint outer pseudoring very well, in part because it extends a little outside the field of view. However, it is very prominent in an HI map obtained by Mundell et al. (1999), who also detected an elliptical ring of HI gas in the main oval.
NGC 4151 is a well-known Seyfert 1 galaxy with an especially bright nucleus. In the atlas image, the nucleus is bright enough to show diffraction spikes.