De Vaucouleurs Atlas Type: (R')SA(r)ab pec
Telescope: Kiso Schmidt
North down , East right
Field Dimensions: 10.4 x 7.8 arcminutes
RC3 Type: (R)SA(rs)ab
RSA Type: Sab(s)II
Surface Brightness Range Displayed: 16.0-26.0 mag per square arcsec
Absolute Blue Magnitude: -20.6
Elmegreen Spiral Arm Class: AC 6
De Vaucouleurs Atlas Description:
This famous object, known for its ``Black Eye" of major near-side extinction, has several other features of interest. In the inner regions, there is a well-defined inner ring whose morphology is greatly affected by the large dust structure. Very weak spiral structure, opening in a counterclockwise direction, breaks from near this ring. Further out, two very diffuse, low contrast spiral arms form an outer pseudoring winding in a clockwise direction. Thus, NGC 4826 is possibly a counterwinding spiral like NGC 4622 (Buta, Byrd, and Freeman 2003), only the features in the latter galaxy are much more obvious. The V-I color index map shows, apart from the obvious dust zone, very slightly enhanced blue colors in the inner ring and in the inner spiral structure. No color contrast is associated with the outer pseudoring .
NGC 4826 is believed to be the product of a merger of a massive gas-poor disk galaxy with a low mass dwarf. This was brought to light by Braun et al. (1992, 1994), who showed that an outer disk of HI gas is counter-rotating with respect to an inner disk of ionized gas. Van Driel and Buta (1993) noted the subtle counterwinding spiral structure and its similarity to NGC 4622 , and suggested the inner spiral is a single leading arm if the HI disk rotates in the same sense as the stellar disk. However, Rix et al. (1995) later showed definitively that the HI gas counter-rotates with respect to the stellar disk as well, implying that the two outer arms are leading. This is similar to the current view of NGC 4622 (Buta, Byrd, and Freeman 2003), and suggests that counterwinding spiral structure may owe its origin to an interaction or minor merger .