Post-asymptotic giant branch evolution in the Large Magellanic Cloud: A study of the central stars of planetary nebulae

We present medium- and broadband Hubble Space Telescope (HST) photometry of a sample of 35 central stars (CSs) of planetary nebulae (PNs) in the Large Magellanic Cloud (LMC). The observations were made with the Wide Field Planetary Camera 2 (WFPC2) and Space Telescope Imaging Spectrograph instruments on board the HST. By observing LMC objects, our sample is free of the distance uncertainty that is the dominant source of error in the determination of CS luminosities in Galactic PNs. By observing with the HST we resolve the nebula, and therefore we often detect the CSs unambiguously. We obtain core masses of 16 of the objects by comparing their positions on the H-R diagram with theoretical evolutionary tracks, once we determine the stellar effective temperature through Zanstra analysis. This sample of CS masses is the largest and most reliable set obtained in an extragalactic environment. We find an average mass of 0.65 M., although a few of the objects have very high mass. This average value is consistent with the average mass of the white dwarf population in the Galaxy. As the immediate precursors of white dwarfs, the study of the mass distribution of PN CSs should help to constrain the initial-to-final mass relation within environments of differing metallicity. Finally, by exploring the physical connections between the star and the nebula, we establish the importance of the study of PNs in the LMC to constrain the energy input from the wind during the post-asymptotic giant branch phase.