NGC 7187 - (R)SAB(r)0+

NGC 7187

De Vaucouleurs Atlas Type: (R)SAB(r)0+

Filter: B

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

RC3 Type: (R)SA(r)0+
RSA Type: -----
Surface Brightness Range Displayed: 18.0-26.0 mag per square arcsec
Absolute Blue Magnitude: -19.2

De Vaucouleurs Atlas Description:

NGC 7187 is an exceptional double-ringed galaxy having little trace of a bar. The inner ring is sharp and slightly knotty, and is a very well-defined feature. In a color index map (Buta 1990a), the ring shows enhanced blue colors and is a site of active star formation (see also the H-alpha image in Crocker, Baugus, and Buta 1996).

Inside the ring, Buta (1990a) identified two perpendicularly aligned oval zones, only the largest of which is easily seen in the Atlas image (see also Wozniak et al. 1995; Erwin 2004). Both of these ovals are small and weak, and we recognize the larger one in the classification SAB. The outer ring is much fainter than the inner ring and is mostly detached. In contrast to the almost perfectly circular shape of the inner ring , the outer ring is oval and slightly asymmetric. The S0+ classification is adopted because the features are strong and there is no clear spiral structure. This object demonstrates that clear S0s can have recent star formation, but usually only in the form of closed rings.