The post-common-envelope binary nucleus of the planetary nebula IC~4776: Neither an anomalously long orbital period nor a Wolf-Rayet binary

Abstract

The orbital period distribution of close binary stars consisting of a white dwarf and a main-sequence star (WDMS) is a powerful observational constraint on population synthesis models of the poorly understood common-envelope (CE) interaction. Models have often struggled to reproduce the small number of post-CE WDMS binaries with anomalously long orbital periods greater than $\sim$4 d, though recent studies suggest that in longer period systems recombination energy may help contribute to the efficient ejection of the CE. Planetary nebulae (PNe) are an emerging source of rare long period post-CE binaries which can act as powerful complementary constraints on population synthesis models to more traditional post-CE binary populations. A tentative 9.0 d orbital period was recently proposed for the central star of the PN IC~4776, potentially one of the longest periods observed in post-CE WDMS binaries. Here we present SALT HRS observations of IC~4776 that rule out a 9.0 d orbital period, as well as the previously suggested Wolf-Rayet classification of the primary. The SALT HRS data establish a 3.11 d orbital period and rule out Of and Wolf-Rayet primary spectral types. Assuming a mass of 0.6 $M_{\odot }$ for the primary and an orbital inclination matching the nebula orientation, we find a companion mass of $0.22\pm 0.03$ $M_{\odot }$, most likely corresponding to an M4V companion. The orbital period of IC~4776 is still consistent with findings of abundance discrepancy factor (ADF) studies of post-CE PNe, but any trends in the ADF distribution derived from the sample remain significantly biased by selection effects.

arXiv comment7 pages, 5 figures, 3 tables. Accepted for publication in MNRAS

References in corpus (42)

• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Common Envelope Evolution: Where we stand and how we can move forward
• Improving PARSEC models for very low mass stars
• RVSAO 2.0: Digital Redshifts and Radial Velocities
• Post-common-envelope binaries from SDSS. IX: Constraining the common-envelope efficiency
• The Effective Temperature Scale of M dwarfs
• First science with SALT: peering at the accreting polar caps of the eclipsing polar SDSS J015543.40+002807.2
• Binary Planetary Nebulae Nuclei towards the Galactic Bulge. I. Sample Discovery, Period Distribution and Binary Fraction
• The effect of common-envelope evolution on the visible population of post-common-envelope binaries
• Post common envelope binaries from SDSS. XII: The orbital period distribution
• The effect of a wider initial separation on common envelope binary interaction simulations
• Monte Carlo simulations of post-common-envelope white dwarf + main sequence binaries: comparison with the SDSS DR7 observed sample
• A comprehensive population synthesis study of post-common envelope binaries
• Binarity and the abundance discrepancy problem in planetary nebulae
• MN48: a new Galactic bona fide luminous blue variable revealed by Spitzer and SALT
• Observational Confirmation of a Link Between Common Envelope Binary Interaction and Planetary Nebula Shaping
• Common envelope events with low-mass giants: understanding the energy budget
• Confirmation of the link between central star binarity and extreme abundance discrepancy factors in planetary nebulae
• KOI-3278: A Self-Lensing Binary Star System
• Radiation-driven winds of hot luminous stars. XV. Constraints on the mass-luminosity relation of central stars of planetary nebulae
• Predicting the Fate of Binary Red Giants Using the Observed Sequence E Star Population: Binary Planetary Nebula Nuclei and Post-RGB Stars
• Monte Carlo simulations of post-common-envelope white dwarf + main sequence binaries: The effects of including recombination energy
• The White Dwarf Binary Pathways Survey I: A sample of FGK stars with white dwarf companions
• On helium-dominated stellar evolution: the mysterious role of the O(He)-type stars
• Post-common envelope binaries from SDSS - XVI. Long orbital period systems and the energy budget of CE evolution
• A radial velocity survey for post-common-envelope Wolf-Rayet central stars of planetary nebulae: First results and discovery of the close binary nucleus of NGC 5189
• The long-period binary central stars of the planetary nebulae NGC 1514 and LoTr 5
• Analysis of chemical abundances in planetary nebulae with [WC] central stars. II. Chemical abundances and the abundance discrepancy factor
• Binary central stars of planetary nebulae with long orbits: the radial velocity orbit of BD+33.2642 (PN G052.7+50.7) and the orbital motion of HD112313 (PN LoTr5)
• Two-colour photometry of the binary planetary nebula nuclei UU Sagitte and V477 Lyrae: oversized secondaries in post-common-envelope binaries
• Far-UV Spectroscopic Analyses of Four Central Stars of Planetary Nebulae
• The white dwarf binary pathways survey - II. Radial velocities of 1453 FGK stars with white dwarf companions from LAMOST DR4
• The central star of the planetary nebula PB 8: a Wolf-Rayet-type wind of an unusual WN/WC chemical composition
• SALT HRS discovery of the binary nucleus of the Etched Hourglass Nebula MyCn 18
• The evolution of the self-lensing binary KOI-3278: evidence of extra energy sources during CE evolution
• Abell 48 - a rare WN-type central star of a planetary nebula
• The planetary nebula IC 4776 and its post-common-envelope binary central star
• SALT HRS discovery of a long period double-degenerate binary in the planetary nebula NGC 1360
• IC 4663: The first unambiguous [WN] Wolf-Rayet central star of a planetary nebula
• [Fe III] emission lines in the planetary nebula NGC 2392
• On the post-common-envelope central star of the planetary nebula NGC 2346
• The post-common-envelope X-ray binary nucleus of the planetary nebula NGC 2392

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