Bibcode
                                    
                            Sowicka, P.; Jones, D.; Corradi, R. L. M.; Wesson, Roger; García-Rojas, J.; Santander-García, Miguel; Boffin, Henri M. J.; Rodríguez-Gil, P.
    Bibliographical reference
                                    Monthly Notices of the Royal Astronomical Society, Volume 471, Issue 3, p.3529-3546
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                        11
            
                        2017
            
  Citations
                                    30
                            Refereed citations
                                    25
                            Description
                                    We present a detailed analysis of IC 4776, a planetary nebula displaying
a morphology believed to be typical of central star binarity. The nebula
is shown to comprise a compact hourglass-shaped central region and a
pair of precessing jet-like structures. Time-resolved spectroscopy of
its central star reveals a periodic radial velocity variability
consistent with a binary system. Whilst the data are insufficient to
accurately determine the parameters of the binary, the most likely
solutions indicate that the secondary is probably a low-mass
main-sequence star. An empirical analysis of the chemical abundances in
IC 4776 indicates that the common-envelope phase may have cut short the
asymptotic giant branch evolution of the progenitor. Abundances
calculated from recombination lines are found to be discrepant by a
factor of approximately 2 relative to those calculated using
collisionally excited lines, suggesting a possible correlation between
low-abundance discrepancy factors and intermediate-period
post-common-envelope central stars and/or Wolf-Rayet central stars. The
detection of a radial velocity variability associated with the binarity
of the central star of IC 4776 may be indicative of a significant
population of (intermediate-period) post-common-envelope binary central
stars that would be undetected by classic photometric monitoring
techniques.
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