New candidate Planetary Nebulae in the IPHAS survey: the case of PNe
  with ISM interaction
  We present the results of the search for candidate Planetary Nebulae
interacting with the interstellar medium (PN-ISM) in the framework of the INT
Photometric H$\alpha$ Survey (IPHAS) and located in the right ascension range
18h-20h. The detection capability of this new Northern survey, in terms of
depth and imaging resolution, has allowed us to overcome the detection problem
generally associated to the low surface brightness inherent to PNe-ISM. We
discuss the detection of 21 IPHAS PN-ISM candidates. Thus, different stages of
interaction were observed, implying various morphologies i.e. from the
unaffected to totally disrupted shapes. The majority of the sources belong to
the so-called WZO2 stage which main characteristic is a brightening of the
nebula's shell in the direction of motion. The new findings are encouraging as
they would be a first step into the reduction of the scarcity of observational
data and they would provide new insights into the physical processes occurring
in the rather evolved PNe.
