IC 1438 - (R1R2')SAB(r)a

IC 1438

De Vaucouleurs Atlas Type: (R1R2')SAB(r)a

Filter: B

Telescope: CTIO 1.5-m
North up , East left
Field Dimensions: 3.0 x 2.3 arcminutes

RC3 Type: (R')SAB(rs)a:
RSA Type: -----
Surface Brightness Range Displayed: 18.0-26.0 mag per square arcsec
Absolute Blue Magnitude: -20.1

De Vaucouleurs Atlas Description:

This galaxy is a another very good example of a four resonance ring galaxy (others being NGC 1079 and 3081), and since the galaxy is face-on, the intrinsic shapes of the rings are seen directly. A weak bar crosses and underfills slightly a highly elliptical inner ring . Inside the bar, a circular nuclear ring is found. Both of these rings are defined by recent star formation (as seen in the color index map; see also Crocker, Baugus, and Buta 1996), and in the case of the inner ring , this star formation concentrates mostly around the ring major axis. Most remarkable is what is seen in the outer disk: an R1R2' OLR ring/pseud morphology where the R1 is most prominent in the I-band and the R2' is most prominent in the B-band (Buta 1995a). This strange dichotomy suggests that the R1 component formed first and left behind a stellar remnant. Most of the current outer star formation is associated with the R2' component.

A possible sequential formation of R1 and R2 components was found in simulations by Byrd et al. (1994). This process could be relevant to the evolutionary history of IC 1438 .