NGC 4689 - (R)SA(rs)bc

NGC 4689

De Vaucouleurs Atlas Type: (R)SA(rs)bc

Filter: B

Telescope: McGraw-Hill 1.3-m
North left , East down
Field Dimensions: 7.1 x 5.3 arcminutes

RC3 Type: SA(rs)bc
RSA Type: Sc(s) II.3
Surface Brightness Range Displayed: 19.5-26.0 mag per square arcsec
Absolute Blue Magnitude: -19.7
Elmegreen Spiral Arm Class: AC 3

De Vaucouleurs Atlas Description:

The (rs) refers to the small, ring-like pattern in the inner regions. Surrounding this feature is a zone of bright, flocculent spiral structure whose boundary is also ring-like. Beyond this zone is a well-defined, diffuse outer ring , an unusual feature for a late-type galaxy like this.

NGC 4689 is a member of the Virgo Cluster . Its star-forming disk has a sharp edge, or truncation (Koopmann and Kenney 2004) that may be environmentally-induced.