The Mass Distribution of the Central Stars of Planetary Nebulae in the Large Magellanic Cloud

Abstract

We present the properties of the central stars from a sample of 54 planetary nebulae (PNe) observed in the Large Magellanic Cloud (LMC) with the Hubble Space Telescope Imaging Spectrograph (STIS). The Hubble Space Telescope's spatial resolution allows us to resolve the central star from its nebula (and line-of-sight stars) at the distance of the LMC, eliminating the dependency on photoionization modeling in the determination of the stellar flux. For the PNe in which the central star is detected, we obtain the stellar luminosities by directly measuring the stellar fluxes through broadband imaging and the stellar temperatures through Zanstra analysis. From the position of the central stars in the H-R diagram with respect to theoretical evolutionary tracks, we are able to determine reliable core masses for 21 central stars. By including the central star masses determined in this paper with the 16 obtained previously using the same technique, we have increased the sample of central star masses in the LMC to 37, for which we find a non-Gaussian mass distribution. The average central star mass for this sample is mCS,LMC = 0.65 ± 0.07 M☉, slightly higher than the one reported in the literature for both white dwarfs and the central stars of PNe in the Galaxy. If significant, this higher average central star mass in the LMC can be understood in terms of a metallicity dependency on mass-loss rates during the asymptotic giant branch, since the LMC has on average half the metallicity of the Galaxy. Finally, for the 37 objects analyzed in the LMC, we do not find any significant correlation between the mass of the central star and the morphology of the nebula.