  We present the analysis of a Chandra observation of the galaxy cluster Abell
133, which has a cooling flow core, a central radio source, and a diffuse,
filamentary radio source which has been classified as a radio relic.
  The X-ray image shows that the core has a complex structure. The most
prominent feature is a "tongue" of emission which extends from the central cD
galaxy to the northwest and partly overlaps the radio relic. One possibility is
that this tongue is produced by Kelvin-Helmholtz (KH) instabilities through the
interaction between the cold gas around the cD galaxy and hot intracluster
medium. We estimate the critical velocity and time scale for the KH instability
to be effective for the cold core around the cD galaxy. We find that the KH
instability can disrupt the cold core if the relative velocity is >~400 km
s^-1. We compare the results with those of clusters in which sharp, undisrupted
cold fronts have been observed; in these clusters, the low temperature gas in
their central regions has a more regular distribution. In contrast to Abell
133, these cluster cores have longer timescales for the disruption of the core
by the KH instability when they are normalized to the timescale of the cD
galaxy motion. Thus, the other cores are less vulnerable to KH instability.
Another possible origin of the tongue is that it is gas which has been uplifted
by a buoyant bubble of nonthermal plasma that we identify with the observed
radio relic. From the position of the bubble and the radio estimate of the age
of the relic source, we estimate avelocity of ~700 km s^-1 for the bubble. The
structure of the bubble and this velocity are consistent with numerical models
for such buoyant bubbles. (abridged)

Astrophysics