Barred galaxies: bar

Note, that the detection of a bar is subject to several observational effects (bandpass, spatial resolution, ...) and bar detection has not been attempted for all the galaxies in the database (and actually bars were searched in only a small fraction of the galaxies, mostly those larger that about 1 arcmin of diameter). Therefore, the parameter bar is strongly biased: The absence of bar=B barely indicates that there is not bar in the galaxy. There are 10104 galaxies with bar=B (in the May 2003 version).

The presence of a bar is also accounted in the morphological type: type.

It is generally thought that 1/3 of the spiral galaxies hold a strong bar, 1/3 are non-barred and the last third have a weak bar. But modern infrared observations tend to reveal bars in galaxies where the optical observations did not show them. Therefore the fraction of barred galaxies may be higher than 1/3. Except the presence of a bar, the properties of the galaxies in the database do not differ significantly between barred and non-barred galaxies.