Maser-emitting planetary nebulae

Planetary nebulae with maser emission (OHPNe and H2O-PNe) are extremely young PNe, since these masers are expected to extinguish shortly after (<1000 yr) the end of the AGB phase. The study of these objects could help us to understand the transformation of nearly spherical envelopes in the AGB into non-spherical PNe, during the evolution of low- and intermediate-mass stars. Up to now, only eight PNe are known to harbour OH and/or H2O maser emission: Vy 2-2, K3−35, IRAS 17347−3139, IRAS 18061−2505, IRAS 17393−2727, JaSt 23, IRAS 16333−4807, and IRAS 15103−5754 (Zijlstra et al. 1989, Miranda et al. 2001, de Gregorio-Monsalvo et al. 2004, Gómez et al. 2008, Uscanga et al. 2012, Uscanga et al. 2014, Gómez et al. 2015, Qiao et al. 2016).