Observations and three-dimensional ionization structure of the planetary nebula SuWt 2

A. Danehkar*, Q. A. Parker, B. Ercolano

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    20 Citations (Scopus)

    Abstract

    The planetary nebula SuWt 2 (PN G311.0+02.4) is an unusual object with a prominent, inclined central emission ellipse and faint bipolar extensions. It has two A-type stars in a proven binary system at the centre. However, the radiation from these two central stars is too soft to ionize the surrounding material leading to a so far fruitless search for the responsible ionizing source. Such a source is clearly required and has already been inferred to exist via an observed temporal variation of the centre-of-mass velocity of the A-type stars. Moreover, the ejected nebula is nitrogen rich which raises question about the mass-loss process from a likely intermediate-mass progenitor. We use optical integral-field spectroscopy to study the emission lines of the inner nebula ring. This has enabled us to perform an empirical analysis of the optical collisionally excited lines, together with a fully three-dimensional photoionization modelling. Our empirical results are used to constrain the photoionization models, which determine the evolutionary stage of the responsible ionizing source and its likely progenitor. The time-scale for the evolutionary track of a hydrogen-rich model atmosphere is inconsistent with the dynamical age obtained for the ring. This suggests that the central star has undergone a very late thermal pulse. We conclude that the ionizing star could be hydrogen deficient and compatible with what is known as a PG 1159-type star. The evolutionary tracks for the very late thermal pulse models imply a central star mass of ~0.64M⊙, which originated from an ~3M⊙ progenitor. The evolutionary time-scales suggest that the central star left the asymptotic giant branch about 25 000 yr ago, which is consistent with the nebula's age.

    Original languageEnglish
    Pages (from-to)1513-1530
    Number of pages18
    JournalMonthly Notices of the Royal Astronomical Society
    Volume434
    Issue number2
    DOIs
    Publication statusPublished - Sep 2013

    Keywords

    • Abundances-planetary nebulae
    • Individual
    • ISM
    • PN SuWt 2

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