De Vaucouleurs Atlas Type: RG

Filter: B

Telescope: HST 2.4-m
North up , East left
Field Dimensions: 2.1 x 1.7 arcminutes

RC3 Type: Ring
RSA Type: -----
Surface Brightness Range Displayed: 19.0-29.0 mag per square arcsec
Absolute Blue Magnitude: -20.8

De Vaucouleurs Atlas Description:

This famous object is the best known and best studied collisional ring galaxy (book section 2.17.5). Higdon (1995, 1996) studied the massive star formation and HI content of the system. Massive star formation is confined to the ring alone, and the distribution of HI is also ringlike. Further out, an HI bridge connects the ring with a small companion galaxy outside the field of the Atlas image. Higdon concluded the Cartwheel was once a low luminosity gas-rich, late-type spiral that was ``splashed" by this companion, triggering a wave of massive star formation. Of particular interest are the radial features inside the ring, known as ``spokes." Higdon (1996) concludes these features are not correctly explained by models of ring galaxies because the spokes have no associated star formation or HI gas. The spokes and other features are further discussed by Struck-Marcell et al. (1996).