Optical spectra of radio planetary nebulae in the large magellanic cloud

Abstract

We present 11 spectra from 12 candidate radio sources co-identified with known planetary nebulae (PNe) in the Large Magellanic Cloud (LMC). Originally found in Australia Telescope Compact Array (ATCA) LMC surveys at 1.4, 4.8 and 8.64 GHz and confirmed by new high resolution ATCA images at 6 and 3 cm (4″/2″), these complement data recently presented for candidate radio PNe in the Small Magellanic Cloud (SMC). Their spectra were obtained using the Radcliffe 1.9-meter telescope in Sutherland (South Africa). All of the optical PNe and radio candidates are within 2″ and may represent a population of selected radio bright sample only. Nebular ionized masses of these objects are estimated to be as high as 1.8 M⊙, supporting the idea that massive PNe progenitor central stars lose much of their mass in the asymptotic giant branch (AGB) phase or prior. We also identify a sub-population (33%) of radio PNe candidates with prominent ionized iron emission lines.