@article{discovery10096146,
       publisher = {BLACKWELL SCIENCE LTD},
          volume = {276},
           month = {September},
            note = {This version is the version of record. For information on re-use, please refer to the publisher's terms and conditions.},
           pages = {167--181},
           title = {Photoionization modelling based on HST images of Magellanic Cloud planetary nebulae - I. SMC N 2 and SMC N 5},
            year = {1995},
         journal = {Monthly Notices of the Royal Astronomical Society},
          number = {1},
            issn = {0035-8711},
          author = {LIU, XW and BARLOW, MJ and BLADES, JC and OSMER, S and CLEGG, RES},
             url = {https://doi.org/10.1093/mnras/276.1.167},
        abstract = {We construct fully self-consistent, detailed photoionization models for two planetary nebulae (PNe) in the Small Magellanic Cloud (SMC), namely SMC N 2 and SMC N 5, to fit optical and UV spectrophotometric observations as well as HST Faint Object Camera (FOC) narrow-band images taken in the light of H{\ensuremath{\beta}}. The derived density structure shows that both PNe have a central cavity surrounded by a shell of decreasing density described by a parabolic curve. For both nebulae, our models fail to reproduce the HST images taken in the light of the [O III] {\ensuremath{\lambda}} 5007 line, in the sense that the observed [O III] {\ensuremath{\lambda}} 5007 surface brightness decreases more slowly outside the peak emission than predicted. An effective temperature of Teff = 111 500 K, a stellar surface gravity of log g = 5.45 and a luminosity of L* = 8430 L? are derived for the central star of SMC N2; similarly Teff = 137 500 K, log g = 6.0 and L* = 5850 L? are derived for SMC N 5. SMC N 2 is optically thin and has a total nebular mass (H plus He) of 0.180 M?, while SMC N 5 is optically thick and has an ionized gas mass of 0.194 M?. Using the H-burning SMC metal abundance (Z = 0.004) evolutionary tracks calculated by Vassiliadis \& Wood, core masses of 0.674 M? and 0.649M? are derived for SMC N 2 and SMC N 5, respectively. Similarly, from the He-burning evolutionary tracks of Vassiliadis \& Wood for progenitor stars of mean LMC heavy-element abundance (Z = 0.008), we find Mc = 0.695 and 0.675 M? for SMC N 2 and SMC N 5, respectively. We find that H{\ensuremath{\beta}} images are needed if one is to derive accurate stellar luminosities directly from photoionization modelling. However, in the absence of an H{\ensuremath{\beta}} image, photoionization models based on [O III] images (and nebular line intensities) yield accurate values of Teff and log g, which in turn allow reliable stellar masses and luminosities to be derived from a comparison with theoretical evolutionary tracks. We show that the correct nebular ionized mass can be deduced from the nebular H{\ensuremath{\beta}} flux, provided the mean nebular density given by the C III] {\ensuremath{\lambda}} 1909/{\ensuremath{\lambda}} 1907 ratio is also known.},
        keywords = {ISM: abundances, planetary nebulae: individual: SMC N2, planetary nebulae: individual: SMC N5, Magellanic Clouds}
}