Properties of UWISH2 PNe candidates

These objects are bright in molecular hydrogen (H2) emission, and many have bipolar morphologies. Through the detection of the Br{gamma} emission line, which traces ionized hydrogen, we find that the majority of the candidate PNe are indeed likely to be PNe, while 2 of the targets are more likely young stellar objects (YSOs) or pre-planetary nebulae (pPNe).

We detect Br{gamma} in 13 objects which have no detection in IPHAS or SHS H{alpha} surveys. This implies that they are potential members of the little-known optically obscured PN population, hidden from wide-field optical surveys. We use the spatial extent of the H2 1-0S(1) and Br{gamma} lines to estimate the evolutionary stage of our targets, and find that W-BPNe (bipolar PNe with pinched waist morphologies) are likely to be younger objects, while R-BPNe (bipolar PNe with large ring structures) are more evolved.