De Vaucouleurs Atlas Type: SB(r)0+
Telescope: NOT 2.5-m
North up , East left
Field Dimensions: 4.0 x 3.0 arcminutes
RC3 Type: SB(r)0+
RSA Type: RSB02
Surface Brightness Range Displayed: 18.0-26.5 mag per square arcsec
Absolute Blue Magnitude: -19.1
De Vaucouleurs Atlas Description:
NGC 4340 looks very similar to the inner regions of both NGC 2859 and NGC 3945 . A clear ansae -type bar crosses a diffuse inner ring , which in this case is better defined than those seen in NGC 2859 and NGC 3945 . Yet, these two galaxies have bright outer rings while NGC 4340 has no trace of such a feature. It is possible that NGC 4340 does indeed have an outer ring , but the ring is too faint to be detected. Deeper images or an HI mapping might distinguish such a feature if it exists. We note, however, that NGC 4340 is a member of the Virgo Cluster , and thus the invisibility of an outer ring , if actually present, is probably not due to Galactic extinction . The cluster environment may be the most important issue. Note that the SB94 classification appears to treat the ring in NGC 4340 as an outer ring . This is inconsistent with other outer rings (such as those seen in NGC 2859 and 3945) which tend to be be approximately twice the size of the bar.
NGC 4340 is a known double-barred galaxy (Erwin 2004 and references therein), although this feature is only weakly evident in the Atlas image.